Glossary

5C See digital transmission content protection (DTCP).

8-bit color With 8-bit color, the color in a picture is derived from 256 colors. Thus, only 256 colors are available to be used in a single picture when using 8-bit color.

10Base-T 10Base-T is one of the more common types of Ethernet Local Area Network (LAN) cabling. 10Base-T specifies 10 Megabits per second (Mbps)—baseband—carried over twisted pair. See also ethernet, local area network (LAN), and Mbps.

56Kbps modems More appropriately called Pulse Code Modulation (PCM) modems, 56 Kbps modems manipulate the way the telephone system works to send data to an analog modem type device at speeds of up to 56,000 bits per second (56Kbps). 56K modems work by using Integrated Services Digital Network (ISDN) telephone equipment at one end of the connection to manipulate the PCM codes sent across the telephone network. When these PCM sample codes reach the Codec, the codes are translated into a specific series of voltage changes that a PCM modem knows how to interpret. Data sent out by a 56 Kbps modem is subject to the same physical restrictions of any modem, so its top back channel speed is 33.6 Kbps. See also pulse code modulation (PCM),integrated services digital network (ISDN), and CODEC.

64QAM 64QAM stands for 64-state Quadrature Amplitude Modulation. 64QAM is the Digital Video Broadcasting (DVB) specified modulations standards for digital cable transmission. See also Digital Video Broadcasting (DVB) and quadrature amplitude modulation (QAM).

720p 720p is a High Definition Television (HDTV) format with 1280 active horizontal pixels and 720 active scanning lines and using progressive scanning. See also high definition television (HDTV), pixel, progressive scanning.

802.11 standard The 802.11 standard is a type of radio technology used for wireless local area networks (WLANs). It is a standard that has been developed by the Institute of Electrical and Electronic Engineers (IEEE). It is also known as IEEE 802.11 or Wi-Fi. See also Institute of Electrical and Electronic Engineers (IEEE) and Wi-Fi.

802.11a 802.11a is an IEEE specification for wireless networking that operates in the 5 GHz frequency range (5.725 GHz to 5.850 GHz) with a maximum 54 Mbps data transfer rate. The 5 GHz frequency band is not as crowded as the 2.4 GHz frequency, because the 802.11a specification offers more radio channels than the 802.11b. These additional channels can help avoid radio and microwave interference. See also Institute of Electrical and Electronic Engineers (IEEE).

802.11b 802.11b is an international standard for wireless networking that operates in the 2.4 GHz frequency range (2.4 GHz to 2.4835 GHz) and provides a throughput of up to 11 Mbps. This is a commonly used frequency. Microwave ovens, cordless phones, medical and scientific equipment, as
well as Bluetooth devices, all work within the 2.4 GHz frequency band. See also Bluetooth wireless technology.

802.11g Similar to 802.11b, the 802.11g standard provides a throughput of up to 54 Mbps. It also operates in the 2.4 GHz frequency band but uses a different radio technology to boost overall bandwidth.

1080i 1080i is a High Definition Television (HDTV) format with 1920 active horizontal pixels and 1080 active scanning lines and using interlace scanning. See also high definition television (HDTV), interlaced scanning (interlace), and pixel.

ABR See available bit rate (ABR).

AC-3 See Dolby AC-3.

access channels Cable operators set aside channels for use by the public, educational institutions, municipal government, or for lease on a non-discriminatory basis. These are called access channels.

access control Access control refers to methods for controlling user access to networks. These methods may include login passwords, time, and computer restrictions. Access control ensures that content is accessed only by those entities authorized to do so, and only in a manner for which they have been authorized.  Primarily, an access control system has three parts: signal scrambling, encryption of electronic keys, which the viewer will need, and the subscriber management system. Access control systems may also be known as conditional access systems or customer access management systems. See also conditional access and encryption.

access criteria The access criteria is the conditional access system specific information needed to build the Entitlement Control Message (ECM). See also Entitlement Control Message (ECM) and conditional access.

access network The access network is part of the carrier network that touches the customer’s premises. The access network may also be referred to as the local drop, local loop, or last mile. See also last mile.

access node An access node is a part of the access network that performs some or all of the following:
◆ modulating forward data onto the access network
◆ demodulating return-path data
◆ enforcing the MAC protocol for access onto the access network
◆ separating or classifying traffic before multiplexing onto the transport network such as differentiating traffic that is subject to QoS guarantees from traffic that receives best-effort support
◆ enforcing signaling
◆ handling passive operations, such as splitting and filtering See also MAC and quality-of-service (QoS).

access point An access point is a wireless Local Area Network (LAN) transceiver or base station that can connect a wired LAN to one or many wireless devices. Access points can also bridge to each other. There are various types of access points and base stations used in both wireless and wired
networks. These include bridges, hubs, switches, routers, and gateways. The differences between them are not always precise, because certain capabilities associated with one can also be added to another. For example, a router can do bridging, and a hub may also be a switch. But they are all involved in making sure data is transferred from one location to another.  See also bridge, hub, router, and local area network (LAN).

access server An access server allows access to content and other data on a network.

acquisition Acquisition refers to the retrieval of content for local storage and/or use.

active application An application in the active state is loaded into the set-top box’s memory
and runs in the foreground.

active streaming format (ASF) Active streaming format is associated with Windows Media Files. The ASF specification defines the structure of complex, synchronized object data streams. Any object can be placed into an ASF data stream, including audio and video data objects, scripts, ActiveX controls, and HTML documents.

actualized audience The actualized audience refers the actual viewers of an interactive
television program. The audience must also have all the necessary equipment, and training to participate in the interactive television experience.

ad avails Ad avails refers to the advertising spots available to a cable operator to insert local advertising on a cable network.

ad clicks Ad clicks refers to the number of times users click on an advertisement on a site.

ad click-through rates The ad click-through rate is the number of times a viewer clicks on an advertisement with a link compared to the number of times that that advertisement link is shown. For example, if an advertisement is shown 1000 times and five people click on it, that advertisement has a click-through rate of 0.5%.

ad cost per click Ad cost per click refers to how much the advertiser pays each time someone clicks on a banner or link, if applicable. See also banner.

ad views The number of times an advertisement is viewed by visitors to a website is called the ad views. Ad views may also be referred to as impressions.

Adaptive Differential Pulse Code Modulation (ADPCM) Adaptive Differential Pulse Code Modulation is a coding method for producing a reduced bit rate Pulse Code Modulation (PCM) signal. See also pulse code modulation (PCM).

adaptive smart antenna An adaptive smart antenna combines multiple antenna elements with signal processing algorithms to optimize its radiation and/or reception\pattern automatically in response to the signal environment. See also antenna.

address (Internet) Internet addresses come in two forms:
◆ a set of numbers, such as 287.1.1.21
◆ alphanumerically, such as http://www.enabletv.com
These generally represent the same address and either one could be typed into the address bar on your browser to get to that Web address. When a user uses the alphanumeric address such as http://www.enabletv.com, computer hardware such as domain name servers, need to change the letters into number (287.1.1.21) before the site can be accessed.

addressable Addressable refers to a cable or satellite set-top box that has a unique identity. The decoder can descramble a signal—program, channel, etc.—for that particular subscriber. See also conditional access.

address bus An address bus is the electronic path that the data travels in the set-top box or in any type of computer. The wider the width of the bus, the faster the data can travel. Therefore, an 8-bit bus is slower than a 32-bit bus.

adjacent channel Two television channels are considered adjacent when their view carriers, either off-air or on a cable system, are 6 MHz apart. FM signals on a cable system, two channels apart are adjacent when their carriers are 400 to 600 kHz apart.

ADPCM See Adaptive Differential Pulse Code Modulation (ADPCM).

ADSL See asymmetric digital subscriber line (ADSL).

Advanced Television Systems Committee (ATSC) The Advanced Television Systems Committee (ATSC) was established in 1983 to develop voluntary technical standards, including interactive television systems and digital high definition television (HDTV). The ATSC is usually thought of as a committee to address the needs of the North American television market. The ATSC standard for HDTV was approved in 1995 and adopted—with the  exception of the mandatory video formats section—by the Federal Communications Commission (FCC) in 1996. It is to replace the analog National Television Systems Committee (NTSC) format in North America. See also National Television Systems Committee (NTSC), high definition television (HDTV), and Federal Communications Commission (FCC).

aerial plant An aerial plant refers to cable that is suspended in the air on telephone or electric utility poles.

agent An agent is an application that performs actions on behalf of a consumer, such as searching based on a profile. See also profile.

AIF See audio interchange file (AIF).

algorithm An algorithm is an automatic signal-processing strategy that varies the way in which multiple antenna elements are employed as a function of operational scenarios.

aliasing Aliasing refers to defects or distortion in a television picture. In analog video, aliasing is most often caused by interference between two frequencies such as the luminance and chrominance. In digital video, aliasing is caused by insufficient sampling or poor filtering of the digital video. Defects are typically seen as jagged edges on diagonal lines and twinkling or brightening of picture detail. Anti-aliasing refers to technologies used to counter this. See also anti-aliasing, chrominance signal, and luminance signal.

allocations Allocations are the assignments of frequencies by the Federal Communications Commission (FCC) for various communications uses—such as television, radio, land-mobile, defense, and microwave—to achieve fair division of the available spectrum and minimize interference among users. See also Federal Communications Commission (FCC).

American National Standards Institute (ANSI) The American National Standards Institute (ANSI) is an organization that works to develop a consensus on a general range of standards for use in the United States. ANSI is not a governmental organization.

amplifier An amplifier is a device that boosts the strength of an electronic signal. In a cable system, amplifiers are spaced at regular intervals throughout the system to keep signals picture-perfect regardless of how far you live from the head-end. See also head-end.

amplitude Amplitude refers to the distance between the high and low points of a waveform.

amplitude modulation Amplitude modulation is the process of impressing information on a radio frequency signal by varying its amplitude. Generally, amplitude modulation is used for the purpose of relaying messages by voices, television, facsimile, or other modes. See also radio frequency (RF).

analog In telecommunications, analog refers to a transmission standard that uses variable frequencies and amplitudes of electrical impulses to emulate the audio waveform of sound. Analog is a traditional form of telecommunications transmission in a constant variable wave, rather than in a packet-based (or digital) form. See also packet and amplitude.

analog device An analog device operates with variables represented by continuously measured quantities such as voltages, resistances, rotations, and pressures.

analog signal An analog signal is solely dependent on magnitude to express the information content.

analog-to-digital converter An analog-to-digital converter is a device that converts a signal whose
input is information in the analog form and whose output is the same information in digital form.

analog TV With an analog television, the signal the television receives is sent as a continuously varying analog waveform. The waveform’s value determines the amount of voltage that will be applied to the electron guns in the back of the picture tube. This directly affects the luminance and chrominance of the picture. In analog television systems, the voltage applied to the electron guns is proportional to the constantly changing video signal voltage. Analog televisions have the following limitations:
◆ Analog television channels are susceptible to interference caused by physical features—such as hills and buildings. This interference often takes the form of ghosting on the picture screen.
◆ The normal television channel occupies a bandwidth of 6 MHz. With analog televisions, the viewer can see only a limited total number of 6 MHz channels, obviously limiting the total number of possible channels the consumer can receive and view without outside electronic help, that is. In addition, many of the frequency bands that could be used by television channels have to be kept empty because analog television channels spaced too close together can interfere with one another.
◆ Although luminance and chrominance signals are separated, the signals can interfere with one another, especially in regions with low signal strength. This can lead to problems with the color display. To watch digital television on an analog television, you need a digital television tuner—in the form of a set-top box/receiver—and some form of antenna or cable connection. See also luminance signal, chrominance signal, ghost, and bandwidth.

ANSI See American National Standards Institute (ANSI).

antenna An antenna is a structure or device used to receive or transmit electromagnetic waves.

antenna array An antenna array is a group of identical antennas arranged and interconnected for achieving greater directivity (gain) or beam shaping. See also gain.

antenna preamplifier An antenna preamplifier is a small amplifier, usually mast-mounted. It is used for amplifying weak signals to a level sufficient to compensate for down-lead losses and to supply sufficient input to system control devices. See also amplifier.

antenna stack An antenna stack is an antenna tower with multiple antennas and supports.

anti-aliasing Anti-aliasing refers to the removing of aliasing effects by filtering and other techniques. See also aliasing.

anti-siphoning Anti-siphoning refers to the Federal Communications Commission (FCC) rules that prevent cable systems from siphoning off programming for pay cable channels that otherwise would be seen on conventional broadcast television. Anti-siphoning rules state that only movies no older than three years and sports events not ordinarily seen on television can be cablecast. See also Federal Communications Commission (FCC) and cablecasting.

API See application programming interface (API).

applet An applet is a small Java program that you can embed in Hypertext Markup Language (HTML) pages. Applets, in contrast to full-fledged Java applications, are not allowed access to certain resources on the local computer, such as files and devices including modems, printers, etc. An applet is designed to do a specific and limited task. See also Hypertext Markup Language (HTML) and Java.

application An application implements the services provided to the viewer. The term application is usually used in the context of the client and server software that is executed when a viewer selects a service.

application boundary An application boundary is a general description of the data elements—such as Hypertext Markup Language (HTML) documents, code files, images, etc.—used to form one application and the logical locator of the entry point. The application boundary is frequently described by a regular expression over the URL language. See also Hypertext Markup Language (HTML) and Uniform Resource Locator (URL).

application instance An application instance is a unique invocation of an application. That is, running the same application twice results in two distinct application instances.

application manager In general, an application manager manages the lifecycle of an application. For example, the application may initialize the resources needed for the application and release the resources when the application exits.

application platform An application platform is the collection of application program interfaces and protocols on which content and applications are developed. The MPE platform is one example of an application platform.

application programming interface (API) An application programming interface is a series of functions that applications can use to make the operating system perform specific tasks. APIs let you program without having intimate knowledge of the device or software to which you are sending commands. An API can consist of classes, function calls, subroutine calls, descriptive tags, etc.

application server An application server executes applications that are required to provide digital services to subscribers. In general, application servers may provide the following applications: virtual channel server, interactive program guide, Dynamic Host Configuration Tool (DHCT) configuration, pay-per-view, and Emergency Alert System (EAS) messaging. See also Pay-Per-View (PPV).

ARPU See average revenue per unit (ARPU).

artifact An artifact can cause problems in the appearance of a video image. Artifacts may occur naturally in the analog and digital video process and need to be removed to achieve a high-quality picture. Most common artifacts in analog video are cross luminance and cross color. Most common artifacts in digital video are macroblocks. See also macroblock.

ASF See active streaming format (ASF).

ASI See asynchronous serial interface (ASI).

aspect ratio The aspect ratio describes the ratio of the picture width to the picture height on the television screen. In National Television Systems Committee (NTSC) and Phase Alternating Lines (PAL) video formats, which are used for conventional analog television, the present standard is 4:3. In wide screen video, the aspect ratio is most often 16:9, but may also be 14:9. In High Definition Television (HDTV), the aspect ratio is 16:9. See also National Television Systems Committee (NTSC), high definition television (HDTV), and Phase Alternating Lines (PAL).

asset Assets consist of a media file such as video, audio, or a still image and the associated metadata. Applications consume assets. See also metadata.

asset management system An asset management system contains a single, logical database of assets that defines metadata and asset relationships. An asset management system generally manages an asset’s lifecycle, the propagation of multiple replicated copies of content on content servers, as well as access of assets via access networks. See also asset, metadata, and content server.

asymmetric connection With an asymmetric connection, data can flow in one direction at a much
higher speed than in the other. Some examples of asymmetric connections are Asymmetric Digital Subscriber Line (ADSL), 56K modems, and satellite downlinks. See also back channel, asymmetric digital subscriber line (ADSL), downlink, and 56Kbps modems.

asymmetric digital subscriber line (ADSL) Asymmetric digital subscriber line (ADSL) is a data communications technology that can piggyback a standard voice telephone connection and a high-speed—up to 8 Mbps—digital data link on to a single-pair local loop connections to a customer premises. ADSL technology is an asymmetric technology, which means that the speed of the digital link to a customer premises is generally not the same speed as the connection coming back. With ADSL, for example, a customer may have only 128 Kbps of outbound bandwidth, but may be able to receive data at speeds of 8 Mbps. See also digital subscriber line (DSL) and bandwidth.

asymmetric encryption With asymmetric encryption, the encryption keys and the decryption keys are not the same, and one key is computationally difficult to determine from the other.

asynchronous Asynchronous refers to a data transmission method that transmits each character independently without reference to a standard clock using stop and start bits.

asynchronous serial interface (ASI) Asynchronous serial interface is a Digital Video Broadcasting (DVB) standard for the transfer of MPEG-2 transport streams. See also Digital Video Broadcasting (DVB), MPEG-2, and transport stream.

asynchronous transfer mode (ATM) With asynchronous transfer mode, information is organized into cells and then transferred. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic. Information is transferred and switched in 53-byte cells made up of 48 data bytes, plus 5 header bytes for special information. ATM is designed to support multimedia.

asynchronous transmission protocol The asynchronous transmission protocol is a switching and transport protocol for efficient transmission of both constant-rate and bursty information in broadband digital networks. The asynchronous transmission protocol places start and stop sequences at the beginning and end of each byte, instead of at the beginning and end of each larger block of data sent.  The Asynchronous Transfer Mode (ATM) digital stream consists of fixed-length packets called cells, each cell includes a 5-byte header and a 48-byte information payload. This increases the overhead required to transmit each byte and decreases throughput. See also asynchronous transfer mode (ATM).

ATM See asynchronous transfer mode (ATM).

ATM adaption layer The asynchronous transfer mode (ATM) adaption layer adapts variable length packets to fixed-length ATM cells. See also asynchronous transfermode (ATM), ATM cell, and packet.

ATM cell An asynchronous transfer mode (ATM) cell is a digital information block of fixed length (53 octets) identified by a label at the ATM layer. See also asynchronous transfer mode (ATM).

ATSC See Advanced Television Systems Committee (ATSC).

attenuation Attenuation is the decrease in amplitude of a signal between any two points in a circuit. Attenuation is usually expressed in decibels. Attenuation is the opposite of amplification. See also amplitude.

ATV forum The Advanced TV Forum is a membership association founded in 2000 that promotes interactive television. It supports the Enhanced Content Specification originally developed by the Advanced Television Enhancement Forum (ATVEF). See also Advanced Television Enhancement Forum (ATVEF).

ATVEF See Advanced Television Enhancement Forum (ATVEF).

audience flow Audience flow refers to whether viewers will stay with a channel or program when the program they have been watching ends, or a commercial(s) is presented during the program, as commercials naturally tend to disturb/interrupt the viewing experience. These changes can even include the viewer leaving the program due to interactive television. This has been an argument of many television producers who do not want any members of their audience leaving their presentation, even temporarily, for any reason.

audio interchange file (AIF) Audio Interchange Format (AIF) is an audio file format developed by Apple Computer to store high quality sound and musical instrument files (data).

authentication Authentication is a technique by which access to the Internet of another network resource requires the user to identify himself or herself using a name (log-in) and password.

automatic gain control Automatic gain control is a circuit that automatically controls the gain of an amplifier so that the output signal level is virtually constant for varying input signal levels. See also amplifier and gain.

automatic slope control Automatic slope control is circuitry which permits amplifier response
compensation for varying slope (tilt) at its input. See also amplifier.

available bit rate (ABR) Available bit rate is an asynchronous transfer mode (ATM) layer service
where the limiting ATM-layer transfer characteristics provided by the network may change subsequent to the connection established. See also asynchronous transfer mode (ATM).

average revenue per unit (ARPU) The average revenue per unit is commonly used as a financial benchmark in the cable industry to measure average revenue per cable subscriber.

axis The X axis is a horizontal line across the center of the screen (digital picture), the Y axis is a vertical line across the center of the screen (digital picture) and the Z axis is the third dimension, perpendicular to the X and Y axis. It indicates depth and distance.

azimuth Azimuth is a term used when tracking satellites. It indicates the left/right direction or east/west.

B channel B channel refers to an Integrated Services Digital Network (ISDN) Bearer channel. It can be used to carry voice or data connections at speeds of 56 or 64Kbps. See also integrated services digital network (ISDN).

back channel The back channel is an asymmetric data connection that provides a physical method for the viewer to send information. The information may include requests or demands back to the content provider. A back channel is a two-way communications link between the television viewer (end-user) and the interactive content provider. The back channel is typically a modem and attached telephone line. See also content provider, return path and reverse channel.

back door In networking security, the back door refers to a hole in a compromised system that allows continued access to the system by an intruder even if the original attack is discovered.

back end Back end refers to a program that handles details behind the scenes, performing tasks not directly controlled by the user. It also refers to the infrastructure of servers, databases, and software that supports the actions of users who interact with delivered content.

back porch The back porch is that portion of the composite picture signal which lies between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse.

backbone A backbone is a high-speed line or series of connections that form a major pathway within a network. The term backbone is relative to the size of the network, because a backbone in a small network will likely be much smaller than many non-backbone lines in a large network.

backbone microwave system A backbone microwave system is a series of directional microwave paths carrying common information to be relayed between remote points. A backbone microwave system is engineered to allow insertion of signals, dropping off of signals, and switching of signals along its length at designated relay points.

background noise In an amplifier or other device that draws current, there is always some noise output in addition to the desired signal. This is referred to as background noise.
 
backhaul Backhaul refers to sending a program or newsfeed via satellite from an isolated (local) area back to the main distribution area so it can be rebroadcasted via satellite.  See also radio frequency (RF).

banding Banding is a television picture problem where brightness or color is distorted. Banding is often the result of too few bits being used to create the picture.

bandwidth Bandwidth refers to the measure of the capacity of a transmission channel or the difference between the highest and lowest frequency levels. Bandwidth is the information-carrying capacity of a communication channel. The amount of transmission capacity possessed by a system or a specific location in a system is also referred to as the bandwidth. A television channel occupies a bandwidth of 6 million cycles per second (6 MHz). Cable system bandwidth occupies 50 to 300 MHz on the electromagnetic spectrum.

banner A banner is a dynamic, on-screen display of information, superimposed over content, sharable among various applications authorized to do so at a given time. Items displayed in a banner may have interactive characteristics. There may be different banners for different purposes such as the volume indicator, program information, and alerts. All banners must be coordinated so that they do not conflict in position or content, and remain aesthetically pleasing.

barker In conventional cable, a barker is a service that furnishes repeated information. For example, if the viewer selects a channel number for a premium service to which he or she is not subscribed, the set-top box may tune to a barker channel that advertises the premium service. In the hybrid analog/digital system, the barker data need not occupy a full analog channel, but may be generated from Vertical Blanking Interval (VBI) data, other available data sources, or locally at the set-top box. Barkers may be simple presentations or can be interactive, on-demand applications. See also vertical blanking interval (VBI).

baseband transmission Baseband transmission is a type of digital data transmission in which each
medium (wire) carries only one signal, or channel, at a time. In contrast, broadband transmission enables a single wire to carry multiple signals at the same time. Baseband networks are simpler and cheaper than broadband networks. Most communications involving computers uses baseband transmission. This includes communications from the computer to devices—such as printers and monitors—and communication via modems.

base stream A stream is a sequence of bytes. The base stream is the stream of data before any additional data is added.

basic cable Basic cable refers to the basic program services distributed by a cable system for a basic monthly fee. These include one or more local broadcast stations, distant broadcast stations, non-pay networks, and local origination programming.

BAT See Bouquet Association Table (BAT).

baud rate The baud rate is the measure of the speed of transmission of a digital code.

BER See bit error rate (BER).

bevel Adding a beveled effect to a graphic image gives the image a raised appearance by applying highlight colors and shadow colors to the inside and outside edges.

binary data Binary data is the mathematical language that computers read to operate. It consists of a series of ones and zeros known as bits. Where and when there is a 1, there is an electrical signal. Where and when there is a zero, there is no electrical signal.

binary files Binary files are any files that contain anything other than text.

bit Bit is an abbreviation of binary digit. A bit can be one of the two binary characters, either a 1 or 0. Bandwidth is usually measured in bits per second. See also bandwidth.

bit bucket A bit bucket is any device capable of storing any kind of digital data, be it video, audio, or any other type.

bit budget The bit budget refers to the total number of bits available on the media being used, such as a DVD, CD-ROM, or hard drive. See also bit.

bit depth The bit depth refers to the number of levels that a pixel might have, such as 256 with an 8-bit depth or 1,024 with a 10-bit depth. See also bit and pixel.

bit error rate (BER) The bit error rate (BER) refers to the number of erroneous bits divided by the total number of bits over a stipulated period of time. Usually, the bit error rate is expressed as a number and a power of 10, per second.

bit parallel The bit parallel is the transmission of digital video a byte at a time, down a cable with multi-conductivity capacity such that each pair of wires carries a single bit.

bits per second (b/s) Bits per second refers to the measure of data transmission speed over communication lines based on the number of bits that can be sent or received per second. Bits per second—bps—is often confused with bytes per second—Bps. While bits is a measure of transmission speed, bytes is a measure of storage capability. 8 bits make a byte, so if a wireless network is operating at a bandwidth of 11 megabits per second (11 Mbps or 11 Mbits/sec), it is sending data at 1.375 megabytes per second (1.375 MBps). See also bit rate.

bit rate The bit rate is the rate of a binary-coded transmission which is the number of bits per second.

bit serial Bit serial refers to the transmission of digital video a bit at a time down a single conductor such as coaxial cable. It also can pertain to transmission through fiber optics. See also coaxial cable.

bit stream A bit stream is a continuous series of bits transmitted on a line.

bitmap A bitmap is an image stored as pixels mapped across the stream. See also pixel.

black burst Black burst is a composite video signal with a totally black picture. Black burst is used to sync video equipment together so that video output is aligned. Black burst tells the video equipment the vertical sync, horizontal sync, and the chroma burst information.

black level The black level refers to the level of a video signal that corresponds to black. The black level represents the darkest an image can get. This defines what black is for the particular image system.

blanking (picture) Blanking is the portion of the composite video signal whose instantaneous amplitude makes the vertical and horizontal retrace invisible. Blanking also refers to the sync signal determining the size of the black sync bar at the bottom of your television picture. See also amplitude and composite video signal.

bleeding Bleeding refers to an image that continues beyond the desired boundary.

block A block is a rectangular area of picture, usually 8x8 pixels in size, which is individually subjected to Discrete Cosine Transfer (DCT) coding as part of the digital picture compression process. DCT coding is a method of data compression of digital video. See also pixel.

block tilt Block tilt is a method of setting the output levels of all low-band channels at a given number of decibels (dB) lower than high-band channels.

blocked Blocked describes content that the viewer has locally restricted from use. Traditionally, a service is the only element that can be blocked. A viewer can block the viewing of a channel by specifying one or more blocking parameters, such as time, channel, or content.

blooming Blooming refers to an image that continues beyond its desired boundary, but is less uniform than bleeding. Blooming is sometimes caused when video becomes whiter-than-white, in which a line that is supposed to be thin becomes fat and fuzzy. See also bleeding.

Bluetooth wireless technology Bluetooth wireless technology is a specification for linking portable
computers, personal digital assistants (PDAs), and mobile phones for short-range transmission of voice and data across a global radio frequency band without the need for cables or wires. Bluetooth is a frequency-hopping technology in the 2.4 GHz frequency spectrum, with a range of 30 feet.

border Border refers to a split-screen effect that makes a visible line between the pictures on the screen.

bouquet A bouquet is a number of product or services that are combined and then marketed as only one product or service.

Bouquet Association Table (BAT) A Bouquet Association Table provides information regarding bouquets. It gives the name of the bouquet and provides a list of services for each bouquet. See also bouquet.

branding Branding is the placement of a corporate logo to identify a service or show.

breezeway The breezeway refers to that portion of the video waveform between the rising edge of the horizontal sync and the start of color burst. See also color burst.

brick mode When a set-top box is in brick mode, all functions are stopped, including the ability to power on.

bridge A bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol (for example, wireless, Ethernet, or token ring). Wireless bridges are commonly used to link buildings in campuses. See also local area network (LAN) and token ring.

bridged tap A bridged tap refers to wires that are connected to a network in which one end of the wire is unconnected to proper termination equipment. This could happen, for example, if a consumer or technician removes devices without completely disconnecting the old device.

bridger amplifier The bridger amplifier is housed in the same case as the trunk amplifier. It taps the trunk at about +20 dBmV and splits the signal into 2 to 4 feeder lines. Trunk amplifiers serve not only to boost the signal and pass it along, but also to provide branching lines, called feeders, for distribution of the signals to subscribers. See also amplifier and trunk amplifiers.

brightness Brightness refers to the intensity of the video level and refers to how much light is emitted by the display.

broadband 1. Broadband refers to very fast content delivery networks capable of delivering high bandwidth—which is a great many bits per second. Cable television and satellites use broadband. Broadband ranges from 550 MHz to 1GHz. A single television channel requires 6 MHz. In the digital delivery system, bandwidth is most often measured in bits per second. 2. Broadband can be used to denote a higher than currently normal bandwidth connection for a consumer. See also bandwidth.

broadband communications system Broadband communication system is frequently used as a synonym for cable television. It can describe any system capable of delivering wide-band channels and services.

broadband modulation Broadband modulation is the transfer of information by a radio signal that requires a certain minimum amount of spectrum space. This minimum depends on the rate at which this information is conveyed. Broadband modulation is sometimes called wideband modulation. See also wideband.

broadband network bridge More commonly known as a cable modem, a broadband network bridge is a device that bridges radio-wave-like signals sent over cable television wiring to standard Ethernet local area network (LAN) connections, which you can plug into a computer‘s Ethernet network card. See also cable modem, ethernet, and local area network (LAN).

broadcast A broadcast refers to the act of distributing a signal from a single source to all the desired destinations.

broadcast address A broadcast address is a predefined destination address that denotes the set of all service access points. See also service access point (SAP).

broadcast application A broadcast application runs on a set-top box that is loaded through in-band information, and inserted either at the head-end or by a content provider further upstream. See also content provider, head-end, and upstream.

broadcast control channel The broadcast control channel contains telemetry, identification, and
configuration data. It is broadcast continually from the base station.

broadcast file system (BFS) A broadcast file system is a data carousel system by which application data can be stored on an application server and transmitted frequently to the set-top boxes for application use. It controls a file and directory structure broadcast repeatedly in a carousel over the cable network. See also application server.

broadcaster’s service area A broadcaster’s service area is the geographical area encompassed by a station’s signal.

broadcasting Broadcasting refers to the dissemination of any form of radio electric communications by means of Hertzian waves intended to be received by the public. It is the transmission of over-theair signals for public use.

brouter A brouter is a device that routes specific protocols, such as TransmissionControl Protocol/Internet Protocol (TCP/IP) and IPX, and bridges otherprotocols, thereby combining the functions of both routers and bridges.See also Transmission Control Protocol/Internet Protocol (TCP/IP).

BSkyB British Sky Broadcasting is a leading provider of sports, movies,entertainment, and news. BSkyB’s channels are received by almost ten million households in the United Kingdom, including five million digital satellite subscribers. Sky’s majority owned company, Open, is developing the network’s interactive services.

burst A burst refers to a sync signal for controlling the hue and color accuracy of the television picture.

burst error second A burst error second is any errored second containing at least 100 errors.

bus A bus is a local area network (LAN) topology in which all the nodes are connected to a single cable. All nodes are considered equal and receive all transmissions on the medium. See also local area network (LAN) and node.

business-to-business (B-to-B) Business-to-business refers to an e-commerce site used to facilitate business between two separate businesses.

business-to-consumer(B-to-C) Business-to-consumer refers to an e-commerce site used to facilitate business between a business and a consumer.

byte A byte is a unit of data measurement made up of eight bits and is short for binary term. One byte can represent a character such as a letter, number, or punctuation mark. Large groups of bytes—megabytes and gigabytes—are typical units of measurement for items such as RAM and hard drive size. See also bit.

cable loss Cable loss defines the amount of cable loss that an amplifier is aligned—or pre- equalized—through during factory alignment. Aligning an amplifier through cable creates a tilted gain response. See also amplifier.

cable modem A cable modem uses the bandwidth of a given cable system. Because cable modems provide Internet access over cable television networks (which rely primarily on fiber optic or coaxial cable), cable modems are much faster than standard modems that use telephone lines and switching hardware. Typically, a cable modem can provide 1.5-3 Mbps download and 128 kilobits upload. However, those speeds can be much higher, even up to 30 Mbps. Though the cable modem is capable of high speeds, the cable provider usually caps the connection speed. Usually, you do not need a separate telephone connection to upload with if you have a cable modem as both upload and download is done through the same cable modem. Cable modems also give a permanent connection to the Internet. See also bandwidth and coaxial cable.

cable modem telco return interface (CMTRI) Cable modem telco return interface is the upstream interface between a Telco modem attached to, or inside of, a cable modem and the cable modem termination system (CMTS). See also cable modem and cable modem termination system (CMTS).

cable modem termination system (CMTS) Located at the cable television system head-end or distribution hub, a cable modem termination system provides complementary functionality to the cable modems to enable data connectivity to a wide area network. See also head-end, cable modem, hub, and Wide Area Network (WAN).

cable modem to CPE interface (CMCI) The cable modem to consumer premises equipment (CPE) interface is the part of the Data Over Cable Service Interface Specification (DOCSIS) specification defining the communication between the cable modem and consumer premise equipment devices. See also customer premises equipment (CPE), cable modem, and Data Over Cable Service Interface Specifications (DOCSIS).

cable network A cable network refers to the cable television plant that would typically be used for data over cable services. Such plants generally use a downstream path in the range of 54 MHz on the low end to a high end in the 440 to 750 MHz range and an upstream path in the range of 5 to 42 MHz.  Customers in a cable network share a common communication path for upstream and a separate common path for downstream—that is,effectively a pair of unidirectional buses.

cable plant Cable plant refers to the central equipment and broadcasting headquarters of a cable operator. All initial broadcasts from the content providers are sent to the cable plant, aggregated, re- encoded, and broadcast to itsset-top box network.

cable powered Cable powered refers to devices obtaining AC power simultaneously with radio frequency (RF) on the coaxial cable. See also coaxial cable and radio frequency (RF).

cable powering Cable powering is a method of supplying power to solid-state cable television equipment by using the coaxial cable to carry both signal and power simultaneously. See also cable system and coaxial cable.

cable system A cable system is a facility that provides cable service in a given geographic area. A cable system is comprised of one or more head-ends. See also head-end.

cable television Cable television is the system network for the distribution of the television signal and digital data by cable—coaxial, twisted pair, or fiber optic. See also coaxial cable, fiber optics, and twisted pair.

cable television relay services The cable television relay services are a terrestrial microwave frequency band used to relay television, FM radio, cablecasting, and other band signals from the original reception site to the head-end terminal for distribution over cable. See also head-end and cablecasting.

cable termination Radio frequency (RF) signals travelling in coaxial cable reflect off any impedance that does not match the 75-ohm impedance of the cable. This reflection causes serious signal distortion. For this reason, the ends of all the trunk and distribution cables are terminated with a 75-ohm load to ground. This is referred to as cable termination. See also coaxial cable and radio frequency (RF) and ohm.

cablecasting Cablecasting is used to originate programming over a cable system. Cablecasting includes public access programming.

CableSCAN CableSCAN is a software product developed by TapSCAN to tabulate Nielson household and demographic data for cable television.

Canal+ Canal+ Technologies is an international provider of digital and interactive television software solutions. Their main headquarters are in France. The open system strategy of it’s middleware product—MediaHighway—is consistent with the concept basis of the OpenCable Application Platform (OCAP). See also OpenCable™ Application Platform (OCAP).

carriage Carriage refers to a cable system’s procedure for carrying the signals of television stations on its various channels. Federal Communications Commission (FCC) rules determine which signals cable systems must or may carry. See also cable system and Federal Communications Commission
(FCC).

carrier A carrier is an alternating-current (AC) wave of constant frequency, phase, and amplitude. By varying the frequency, phase, or amplitude of a carrier wave, information is transmitted. See also the first definition of frequency and amplitude.

carrier hum modulation Carrier hum modulation is the peak-to-peak magnitude of the amplitude distortion relative to the radio frequency (RF) carrier signal level due to the fundamental and low order harmonics of the power-supply frequency. See also amplitude, modulation, and radio frequency (RF).

carrier sense multiple access with collision avoidance (CSMA/CA) Carrier sense multiple access with collision avoidance (CSMA/CA) is the principle medium access method employed by the Institute of Electrical and Electronic Engineers (IEEE) 802.11 specification for wireless local area networks (LANs). It is a listen-before-talk method of minimizing—but not eliminating—collisions caused by simultaneous transmission by multiple radios. IEEE 802.11 states that the collision avoidance method must be used rather than the collision detection method, because the standard employs half duplex radios—radios capable of transmission or reception—but not both simultaneously. See also carrier sense multiple access with collision detection (CSMA/CD) and Institute of Electrical and Electronic Engineers (IEEE).

carrier sense multiple access with collision detection (CSMA/CD) Carrier sense multiple access with collision detection (CSMA/CD) is the Ethernet media access method. With carrier sense multiple access with collision detection, all network devices contend equally for access to transmit. If a device detects a signal from another device while it is transmitting, it aborts transmission and retries after a brief pause.

carrier-to-noise ratio The carrier-to-noise ratio is the square of the ratio of the root mean square of the voltage of the digitally-modulated radio frequency (RF) carrier to the root mean square of the continuous random noise voltage in the defined measurement bandwidth. If not specified explicitly, the measurement bandwidth is the symbol rate of the digital modulation; for video, the carrier-to-noise ratio is 4 MHz. See also bandwidth and radio frequency (RF).

cartridge A cartridge is a container for recorded programming designed to be shown on a television receiver. The cartridge contains a reel of motion picture film, videotape, or electronically embossed vinyl tape—blank or recorded—and uses an external take-up reel. See also cassette.

cascade depth The cascade depth is the number of amplifiers between the head-end and the specific subscriber. See also amplifier and head-end.

cascading style sheet (CSS) The cascading style sheet recommendation from the World Wide Web Consortium (W3C) defines the derivation of web page contents from multiple sources, with a hierarchical order of precedence. This makes it possible, for example, to change just one format page in order the change the appearance of many derived content pages. CSS 1 is implemented in the current versions of the Netscape and Microsoft browsers.

cassette A cassette is a self-contained package of reel-to-reel blank or recorded film, videotape, or electronically embossed vinyl tape which is continuous and self-rewinding. A cassette is similar to a cartridge, but of slightly different design. See also cartridge.

CAT See Conditional Access Table (CAT).

CATV See community antenna television system (CATV).

CBR See constant bit rate (CBR).

CDMA See code division multiple access (CDMA).

C-band satellite A C-band satellite is a 3.7-4.2 gigahertz (Ghz) frequency band used for distribution of programming by most satellite and cable networks.

cell A cell is an asynchronous transfer mode (ATM) layer protocol data unit. See also asynchronous transfer mode (ATM) and ATM adaption layer.

central casting Central casting refers to the management of various aspects of broadcast operations, including technical, accounting, and programming support for multiple broadcast facilities from a central location.

central office The central office is a switching system that connects lines-to-lines and lines-to-trunks. The term central office is sometimes used loosely to refer to a telephone company building in which a switching system is located and to include other equipment—such as transmission system terminals—that may be located in such a building.

certificate of compliance Before a cable system can carry television broadcast signals, the cable
system must get a certificate of compliance. The certificate of compliance indicates approval by the Federal Communications Commission (FCC). See also Federal Communications Commission (FCC).

channel A channel is the transmission path between two points. The term channel may refer to a one-way path or a two-way path. A two-way path is when paths in the two directions of transmission are always associated. It is usually the smallest subdivision of a transmission system by means of which a single type of communication service is provided—that is, a voice channel, a teletypewriter channel, or a data channel.

channel-based application A channel-based application launches automatically—bypassing the default service menu—when a subscriber tunes to a specifically configured individual channel. In these cases, the application is considered an integral part of the channel, but the service menu is still  available. See also channel, service, and subscriber.

channel capacity The channel capacity refers to the number of channels available for current or future use on a cable system. See also channel and cable system.

channel number The channel number refers to the traditional numeric value used to select a service. In a digital system, thousands of channel numbers may be in use, compared with roughly fifty channel numbers for analog cable television.

channel scanning Channel scanning refers to selecting a channel by any means other than explicitly specifying a channel by number or content. For example, using channel up/down or favorite functions. See also direct channel selection and channel.

chrominance signal The chrominance signal is that portion of the National Television Systems Committee (NTSC) color television signal that contains the color information. See also National Television Systems Committee (NTSC) and luminance signal.

circuit switching Circuit switching refers to the method for switching information between a source and a destination that uses dedicated network bandwidth. With circuit switching, a connection is established that creates a path through the network. Standard telephone calls use circuit switching. See also bandwidth.

class A class is a description of a set of objects that share the same responsibilities, relationships, operation, attributes, and semantics.

client The client generally refers to the set-top box located at the subscriber’s premises.

clipping Clipping refers to the shearing off of the peaks of a signal. For a picture signal, this may affect either the positive (white) or negative (black) peaks. For a composite video signal, the sync signal may be affected. See also composite video signal.

closed captioning In analog television, closed captioning are subtitles for the hard of hearing and the deaf. The subtitles are transmitted as digital data in the vertical blanking interval (VBI). With closed captioning, the dialogue and sounds in the programming and news are displayed on the television screen. The text is in/on line 21 of the vertical blanking interval. See also vertical blanking interval (VBI).

closed circuit Closed circuit is a system of transmitting television signals in which the receiving and originating equipment are directly linked by cable, microwave, or telephone lines, without broadcasting through the air. See also broadcasting.

cluster A cluster refers to the group of homes passed by a single fiber node. See also fiber node.

clustering Clustering refers to the grouping together of independent cable systems into a larger, more efficient single system that uses some of the same infrastructure.

CLUT See Color Look-Up Table (CLUT).

CMCI See cable modem to CPE interface (CMCI).

CMTRI See cable modem telco return interface (CMTRI).

CMTS See cable modem termination system (CMTS).

coaxial cable Coaxial cable is a copper or copper-sheathed aluminum wire surrounded by an insulating layer of polyethylene foam that is used by cable television systems. The insulating layer is covered with tubular shielding composed of tiny strands of braided copper wire, or a seamless aluminum sheath, and protective outer skin. The wire and the shielding react with each other to
set up an electromagnetic field between them. This system reduces frequency loss and gives cable its great signal-carrying capacity.

co-channel interference One of the primary forms of man-made signal degradation associated with radio, co-channel interference occurs when the same carrier frequency reaches the same receiver from two separate transmitters as a result of spilling over from an adjoining cell. See also cell.

code division multiple access (CDMA) Code division multiple access is a spread spectrum access technology that assigns a code to all multiple access speech bits, sends scrambled transmission of the encoded speech over the air, and reassembles the speech to its original format.

CODEC See Coder-DECoder (CODEC).

Coder-DECoder (CODEC) A codec is a function or device that performs compression and decompression, typically on voice or video streams. See also compression.

cold boot When electricity is cut off from the set-top box, the set-top box loses its network connection and a variety of setting data. A cold boot refers to the act of returning electricity to the set-top box and powering it on from this state.

collision Collision is the result of two network nodes transmitting on the same channel at the same time. The transmitted data is not usable. See also channel.

collision avoidance Collision avoidance refers to a network node characteristic for proactively detecting that it can transmit a signal without risking a collision.

color burst In National Television System Committee (NTSC) color, a color burst normally refers to a burst of approximately 9 cycles of 3.6MHz subcarrier on the back porch of the composite video signal. This serves as a color-synchronizing signal to establish a frequency and phase reference for the chrominance signal. See also National Television Systems Committee (NTSC), back porch, frequency, and composite video signal.

Color Look-Up Table (CLUT) The Color Look-Up Table (CLUT) is a look-up table applied in each region for translating the objects’ pseudo-colors into the correct colors to be displayed.

color subcarrier In National Television System Committee (NTSC) color, the color subcarrier is the carrier whose modulation sidebands are added to the monochrome signal to convey color information, that is, 3.6 MHz (3.579545 MHz). See also National Television Systems Committee (NTSC).

combiner A combiner refers to a signal combining network that allows several discrete inputs to be added into a common bandwidth and that has high isolation between inputs. A combiner may also refer to a power combining network.

combining network A combining network is a passive network that permits the addition of several signals into one combined output with a high degree of isolationbetween individual inputs. It may be a power or frequency combiner. See also combiner.

common carrier A common carrier is any point-to-point communications relay service available to the general public at non-discriminatory rates. The carrier cannot control message content—for example, telephone companies.

common path distortion (CPD) Common path distortion refers to the interference of return path signaling caused by the forward path. See also return path.

communication satellite A communication satellite is an electronic retransmission vehicle located in
space in a fixed earth orbit. Signals are transmitted to the satellite from earth station antenna, amplified, and sent back to earth for reception by other earth station antennas. See also amplifier, antenna, and earth station.

communication server A communication server is a dedicated, standalone system that manages
communications activities for other computers.

community antenna relay service The community antenna relay service is a 12.75-12.95 GHz microwave frequency band that the Federal Communications Commission (FCC) hasassigned to the cable television industry for use in transporting television signals. See also Federal Communications Commission (FCC).

community antenna television system (CATV) The community antenna television system offers the transmission of television signals, including those that originate at over-the-air broadcast stations, to customers on a wired network. CATV was the origin of the cable television networks known today.

composite second order beat (CSO) Composite second order beat refers to the peak of the average level of distortion products due to second-order non-linearity’s in cable system equipment.

composite triple beat (CTB) Composite triple beat refers to the peak of the average level of distortion components due to third-order non-linearity’s in cable system equipment.

composite video signal Composite video signal refers to the complete video signal. For monochrome, the composite video signal consists of the picture signal and the blanking and synchronizing signals. For color, additional color synchronizing signals and color picture information are added. See also blanking (picture).

compression Compression refers to any technique that reduces the size of a file or the required bandwidth for transport of a signal. Compression can be lossless, whereby the decompressed version is absolutely identical to the original. Compression can be lossey, whereby the decompressed version is not identical and is either perceptually identical or impaired.

compulsory license Compulsory license refers to the legislation requiring copyright holders to license users of copyrighted material—cable television operators—on a uniform basis and for a stipulated fee.

conditional access Conditional access systems restrict television program access to certain groups of users either because of concerns for privacy or the desire to collect revenue for the service. Providing conditional access requires secure encryption of the program content, secure decryption in a set-top box for each viewer, and an embedded serial number that is registered in a central conditional access system database. Cable television systems have employed a variety of conditional access systems over the years, many of which have been broken by pirates. The newest approach is to embed the decryption technique in a credit-card-sized point of deployment (POD) module that can be replaced if the system security is compromised. This approach is much more cost effective than replacing the entire set-top box.  Smart cards and/or a private PIN number are most often used to access the services, and/or premium services, by the end-user. The system is primarily made up of three parts:
◆ signal scrambling
◆ encryption of electronic keys that the viewer will need
◆ subscriber management system, which ensures those who have bought the scrambled programming are able to receive and watch it. See also encryption and decryption.

conditional access and encryption Conditional access and encryption refers to the system that provides selective access to programming to individual customers in exchange for payment. See also conditional access and encryption.

Conditional Access Table (CAT) The Conditional Access Table provides information about the conditional access systems used in the multiplex. The information is private and depends on the conditional access system. When applicable, it does include the location of the Entitlement Management Message (EMM) stream. See also Entitlement Management Message (EMM).

connectionless network A connectionless network is a type of packet-switched network in which no logical connection is required between sending and receiving stations. Each data unit or packet includes the source and destination addresses and can take any available route between source and destination. The Internet Protocol (IP) is connectionless. See also packet and Internet Protocol (IP).

constant bit rate (CBR) Constant bit rate is the transmission of data at a fixed data rate. Constant bit rate is a service class intended for real-time applications, or those requiring tightly constrained delay and delay variation, as would be appropriate for voice and video applications. The constant availability of a fixed quantity of bandwidth is considered appropriate for constant bit rate service. See also bandwidth and MPEG-2.

consumer electronics Consumer electronics refers to the electronic products bought or rented by the general public.

consumer profile A consumer profile refers to the data that represents the consumer’s interests and preferences.

consumption Consumption refers to the viewing of, and/or listening to, content.

content Content is one component of an asset. For example, the content may be the physical MPEG file in a movie asset, the binary of an executable code asset, or the physical audio file in an audio asset. Content is different from an asset in that content does not have metadata; it represents only the bits of the component itself.  In the more general broadcasting context, content is movies, shows, advertising, or sports—any programming streamed to the viewer.  See also Moving Picture Experts Group (MPEG), asset, and metadata.

content creator The content creator is the entity that was the original creator of the content. This could be an author, composer, or performer.

content distributor The content distributor acts as the agent for or is the prime distributor of the content.

content owner The content owner owns the intellectual property rights in the content.

content protection Content protection is a mechanism to protect the unauthorized copying of video and audio programming.

content provider In the case of interactive television, the content provider is the entity that literally sends the viewer the television signal—or shows—they watch. Content providers most often are local network television stations affiliates, cable television providers, and/or satellite television providers.

content server A content server is a device used for storing content within an asset management region. Content is loaded onto a content server via a propagation network. The output of a content server may be either via a propagation network, an access network, or both. See also asset,
propagation, and content.

content wrapper The content wrapper is the logical layer accompanying the content for the purposes of describing and/or protecting it, including without limitation metadata, conditional access, and copy protection. See also conditional access and metadata.

contrast Contrast refers to the range of light and dark values in a picture, or the ratio between the maximum and minimum brightness values. A high-contrast picture would contain intense blacks and whites; a lower-contrast picture would contain only shades of gray.

conversion rate The conversion rate is the percentage of consumers exposed to a marketing campaign who will actually do something.

converter A converter is a device attached between the television set and the cable system that can increase the number of channels available on the television. This allows the television to accommodate the multiplicity of channels offered by cable television.

CPD See common path distortion (CPD).

CPE See customer premises equipment (CPE).

CRC See cyclic redundancy check (CRC).

critical length Critical length refers to the distance along a specific cable to causeworst-case mismatch reflection. Critical length is a function of frequency-attenuation-velocity of propagation parameters of specific cable types. See also attenuation, frequency, and velocity of propagation.

cross-modulation Cross-modulation is a form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels. See also modulation.

crossover cable A crossover cable is a special cable used for networking two computers without the use of a hub. Crossover cables may also be required for connecting a cable or digital subscriber line (DSL) modem to a wireless gateway or access point. Instead of the signals transferring in parallel paths from one set of plugs to another, the signals crossover. If an eight-wire cable was being used, for example, the signal would start on pin one at one end of the cable and end up on pin eight at the other end. They cross-over from one side to the other. See also digital subscriber line (DSL) and hub.

cross-ownership Cross-ownership refers to the ownership of two or more kinds of communications outlets by the same individual or business. The Federal Communications Commission (FCC) prohibits television stations and telephone companies from owning cable systems in their service areas. Television networks are prohibited from owning cable systems anywhere in the United States. See also Federal Communications Commission (FCC).

crosstalk Crosstalk refers to the noise passed between communications cables or device elements.

crypto period The crypto period is used for the conditional access system. It is the period when the scrambler uses a particular control word. See also conditionalaccess and scramble.

CSMA/CA See carrier sense multiple access with collision avoidance (CSMA/CA).

CSMA/CD See carrier sense multiple access with collision detection (CSMA/CD).

CSO See composite second order beat (CSO).

CSS See cascading style sheet (CSS).

CTB See composite triple beat (CTB).

current Current is a reference to actual time-of-day. For example, current programs are those that are being broadcast at the current time (that is, the clock time).

customer premises equipment (CPE) Customer premises equipment is the equipment at the end user’s premises. The end user or the service provider may provide the customer premises equipment.

cutoff frequency The cutoff frequency is the frequency beyond which no appreciable energy is transmitted. The cutoff frequency may refer to either an upper or lower limit of a frequency band.

cyclic redundancy check (CRC) A cyclic redundancy check is software used to detect errors in digital messages.

dark fiber Dark fiber is unused fiber-optic cable that has been deployed but does not have the proper electronic and optical equipment to carry optical (light) signals. Generally, dark fiber is considered to be extra fiber that will support future demand for communications capacity.

DASE See Digital Applications Software Environment (DASE).

data channel gateway (DCG) A data channel gateway is the point at which a traditional Internet
Protocol (IP)-based network is interfaced to the hybrid fiber coaxial (HFC) network. See also Internet Protocol (IP) and hybrid fiber coax (HFC).

data communication Data communication is the movement of encoded information by means of electrical transmission systems. Data communication is the transmission of data from one point to another over communication channels.

data compression Data compression is a technique that saves storage space by eliminating gaps, empty fields, redundancies, or unnecessary data to shorten the length of records or blocks. See also compression.

data link layer The data link layer refers to layer 2 in the Open System Interconnection (OSI) architecture. Layer 2 is the layer that provides services to transfer data over the transmission link between open systems. See also Open Systems Interconnection (OSI).

data rate The data rate refers to the amount of information that can be transferred per a unit of time. Bits per second is an example of a data rate. Technically, data rate is the correct term for what is often referred in networks as bandwidth. See also bits per second (b/s) and bandwidth.

data stream A data stream is all the data transmitted through a particular communication line for a particular program, operation, or scheduled transmission.

datacast Datacast refers to the delivery of program-related or non-program-related data files over a one-way broadcasting medium, such as digital television. If communication is required from the viewer back to the broadcaster, an additional back channel is required. See also back channel.

DAVIC See Digital Audio Visual Council (DAVIC).

DBS See direct broadcast satellite (DBS).

DCG See data channel gateway (DCG).

DCT

DCT2000 The DCT-2000 is a basic digital cable set-top box by General Instruments—now Motorola—that includes both cable and telephone modems. Newer models in this series include DCT2500 and DCT2600.

DCT2500 The DCT2500 is a digital cable thin client set-top box by Motorola’s Broadband division. This model offers all the features of their DCT2000, but adds processing power, scaled video, improved graphics, and data extraction for text and other information services.

DCT2600 The DCT2600 is a digital cable thin client set-top box by Motorola's Broadband division. This model offers all the features of their DCT2000, but adds processing power, scaled video, improved graphics, a hard disk for personal video recorder (PVR) use, and data extraction for text and other information services. See also personal video recorder (PVR).

DCT5000 The DCT-5000 is an advanced digital cable thick client set-top box built by General Instruments—now Motorola—that includes both cable and telephone modems.

decoding time stamp (DTS) A decoding time stamp is a field that may be present in a Packetized
Elementary Stream (PES) packet header that indicates the time that an access unit is decoded in the system target decoder.

decryption Decryption is the restoration of data to its original form after it has been encrypted. See also encryption.

dedicated playback channel A dedicated playback channel is used for playing reserved shows, displaying menus, etc. This channel is not used for broadcast content.

delay Delay refers to the elapsed time between the instant when user information is submitted to the network and when it is received by the user at the other end.

delay distortion Delay distortion results from the non-uniform speed of transmission of the various frequency components of a signal. That is, the various frequency components of the signal have different times of travel (delay) between the input and the output of a circuit.

delay spread The delay spread is an effect of multi-path for a digital interface in which multiple reflections of the same signal arrive at the receiver at different times, creating a noticeable degradation in signal quality.

deliverable A deliverable generally refers to an output from a process that has a value, material, or otherwise, to a customer.

delivery Delivery refers to real-time (time synchronous) transfer of content from a server to a display device over an access network. See also access network.

delivery chain The delivery chain is the system that provides the distribution of content and information from providers to consumers.

delivery system The delivery system is the physical medium by which one or more multiplexes are transmitted—for example, satellite system, wide-band coaxial cable, fiber optics, etc. See also coaxial cable, fiber optics, and multiplex.

demodulation Demodulation is what occurs on the receiving end of a transported signal. By doing this, the constant carrier signal is separated from the variable data signals. This is part of what a modem does. See also modem.

demographics Demographics refer to the breakdown of television viewers by such factors as age, sex, income levels, education, and race.

demultiplexing Demultiplexing refers to separating data streams or individual channels of data from a single, multiple channel stream. For example, video and audio streams must be demultiplexed before they are decoded. This is true for muliplexed digital television transmissions. The set-top box or built-in must demultiplex the signal it receives before it can be watched. See also multiplexing.

dense wave division multiplexing (DWDM) Dense wave division multiplexing (DWDM) is a technology that provides in fiber the equivalent of frequency division multiplexing, in metallic wire. Separate parallel channels are transmitted on a single fiber, with one wavelength for each channel. Current products enable 16 channels of 2.5Gb each for a total of 50Gb per fiber. DWDM can operate over existing single-mode fiber, and therefore reduce upgrade costs. See also frequency division multiplexed (FDM).

deployment Deployment refers to a core process workflow in the software engineering process whose purpose is to ensure a successful transition of the developed system to its users. Included for deployment are artifacts such as training materials and installation procedures.

descrambler A descrambler is an electronic circuit that restores a scrambled video signal to its standard form.

design Design is the part of the software development process whose primary purpose is to decide how the system will be implemented. During design, strategic and tactical decisions are made to meet the required functional and quality requirements of a system.
detector A detector is the photodiode in optical receivers.

DHCP See dynamic host configuration protocol (DHCP).

DHEI See digital head-end extension interface (DHEI)

dial-up A dial-up is a data communication established by a circuit-switched connection over a telephone network. Generally, a dial-up is associatedwith less than broadband speeds (56 kbps or less). See also broadband.

differential gain In color television, the differential gain is the change in gain, expressed in dB, for the 3.58-MHz color sub-carrier as the level of the luminance signal is varied from blanking to white. See also luminance signal and blanking (picture).

differential phase The differential phase refers to the variation in phase of the color sub-carrier of a television signal as the level of the luminance signal is varied from blanking to white. See also luminance signal and blanking (picture).

digital 1. In communications and computer technology, digital refers to a method of encoding information using a binary system made up of zeroes and ones. In communications technology, this takes the form of two very different electrical voltages, several volts positive and negative, to represent the two values. This substantial difference in voltages for each state makes it unlikely that minor fluctuations in voltage due to electro-magnetic interference will change the way a signal is interpreted when received. 2. Digital also refers to information that is encoded into bits and bytes, or
packets (zeros and ones, computer binary language). Generally, digital is perceived to be an advanced communication form offering clearer signals and increased transmission capacity. See also bit, byte, encoding, and packet.

Digital Applications Software Environment (DASE) The Digital Applications Software Environment (DASE) is a subcommittee of the Advanced Television Systems Committee (ATSC) seeking to standardize and deploy technologies for enhanced television. The DASE standard provides a higher level of functionality than ATVEF and requires a more powerful enhanced television receiver including a Java run-time engine. The DASE standard is similar in features and scope to the DVB-MHP standard. See also Advanced Television Systems Committee (ATSC) and Advanced Television Enhancement Forum (ATVEF).

Digital Audio Visual Council (DAVIC) The Digital Audio-Visual Council (DAVIC) is a non-profit organization established in Switzerland. DAVIC created complete sets of specifications using emerging digital audio-visual technologies. The DAVIC 1.3.1 set of specifications became an International Standard. It was closely associated with Digital Video Broadcasting (DVB) and several joint standards were developed. See also Digital Video Broadcasting (DVB).

digital compression Digital compression is an engineering technique for converting a cable television signal into a digital format which may then be processed in a manner that requires a smaller portion of spectrum for its transmission. This compressed format allows many channels to be carried in the bandwidth normally required for one signal. This format can also be easily stored and manipulated.

digital facility A digital facility is a switching or transmission facility designed specifically to handle digital signals.

digital head-end extension interface (DHEI) The digital head-end extension interface is a proprietary GI MPEG-2 transport interface used by the GI Integrated Receiver Transcoder (IRT). See also MPEG-2.

digital program insertion (DPI) Digital program insertion is the technique of splicing one digital stream into another to perform advertising insertion.

digital set-top box A digital set-top box is a device that accepts digital encoded television broadcasts and converts them to display on an analog television set.

digital shadow Digital shadow is a term used to denote the viewer’s and/or group of viewers, profile. Data concerning the web pages and other activities that the viewer shows an interest in is accumulated for advertising purposes and for television-commerce (t-commerce) companies to better know what products to offer to sell that individual viewer or groups of viewers.

digital signal A digital signal is a signal that has a limited number of discrete states prior to transmission. This may be contrasted with an analog signal that varies in a continuous manner and may be said to have an infinite number of states.

digital signature The digital signature is the data element that binds a message or transaction to its originator to verify the integrity of the message or transaction.

digital signature algorithm The digital signature algorithm is used to create the digital signature for a given message transaction. It usually involves two parties.

Digital Storage Media-Command and Control (DSM-CC) Digital Storage Media-Command and Control (DSM-CC) is a toolkit for developing control channels associated with MPEG-1 and MPEG-2 streams. DSM-CC is defined as part of the MPEG-2 standard. It is designed for lightweight and fast operation to meet the needs of devices that contain limited memory, such as set-top boxes. See also MPEG-1 and MPEG-2.

digital subscriber line (DSL) A digital subscriber line is high-speed technology to transfer data over an existing twisted-pair copper telephone line. Asynchronous technology provides data transmission rates up to 7 Mbps in one direction, generally within approximately three miles from a telephone central office.

digital transmission Digital transmission is a mode of transmission in which all information to be transmitted is first converted to digital form and then transmitted as a serial stream of pulses. Any signal—voice, data, or television—can be converted to digital form.

digital transmission content protection (DTCP) Digital transmission content protection (DTCP) was jointly created by five companies: Hitachi, Intel, Matsushita (MEI), Sony, and Toshiba. DTCP defines a cryptographic protocol for protecting digital content from illegal copying, interception, and tampering as it traverses a digital interface, such as the one defined by the Institute of Electrical and Electronic Engineers (IEEE) 1394 standard. It is also known as 5C. See also Institute of Electrical and Electronic Engineers (IEEE).

Digital Video Broadcasting (DVB) Digital Video Broadcasting is a European standard for digital television.

digital video recording (DVR) Digital video recording refers to the recording to a local disc in the set-top box.

Digital Video Subcommittee (DVS) The Digital Video Subcommittee is an American National Standards Institute (ANSI)-sponsored standardization committee of the SCTE. See also American National Standards Institute (ANSI).

Digital Visual Interface (DVI) The Digital Visual Interface (DVI) was developed to provide a standard
high-speed uncompressed digital interface between a personal computer and the growing number of Liquid Crystal Display (LCD) and plasma-based monitors. When combined with suitable digital content protection technology (HDCP), the DVI specification also provides the cable and consumer electronics industry with an improved method for connecting a digital set-top box to the digital television display device.

direct channel selection Direct channel selection refers to selecting a channel by entering a channel number, by choice of a channel from the program guide, or following any kind of explicit link to a channel. This is complementary with channel scanning.

direct broadcast satellite (DBS) Direct broadcast satellite is a type of satellite technology that transmitsdirectly to the end user or customer. Direct broadcast satellite describes a frequency allocation and wide spacing between satellites that generally permits higher-powered transmissions through the air to small 18- to 24-inch receiving facilities located on customer premises—point-to-multipoint transport. Direct broadcast satellite is also known as direct-to-home (DTH) satellite.

directional coupler A directional coupler is a high-quality tapping device providing isolation between tap and output terminals.

directive transmission A directive transmission is a directionally focused signal transmission from
a base station to a remote user made possible by certain smart antenna systems with digital signal processing capabilities. These base stations use information obtained during reception to transmit signals selectively toward certain users and away from others.

dish antenna A dish antenna is a high-grain antenna, shaped like a dish, that is used for the transmission and reception of ultra-high-frequency and microwave signals.

display channel number A display channel number is the value assigned to a stream in the program
guide. For example, CNN is on channel 220.

display channel A channel is the means by which a viewer accesses a service. A channel has a number associated with it that the viewer uses to select it. A given service may be accessed by more than one channel.

display device The display device terminates an access network such as a set-top box or digital television.

distant signal Distant signals are broadcast television signals that originate at a point too far away to be picked up by ordinary home reception equipment. A distant signal is also defined by the Federal Communications Commission (FCC) as outside a broadcaster’s license area. Cable systems are limited by FCC rules in the number of distant signals they can offer subscribers. See also Federal Communications Commission (FCC).

distortion Distortion refers to the departure, during transmission and amplification, of the received signal wave form from that of the original transmitted wave form. See also amplifier.

distribution Distribution refers to the transfer of assets over a distribution network using an asset distribution system. Distribution may or may not be realtime. Distribution is usually from a provider to an operator, but may be done between AMRs of an operator.

distribution channel A distribution channel is a method of distributing information and data, such as a television network and/or channel.

distribution hub A distribution hub is a location in a cable television network that performs the functions of a head-end for customers in its immediate area, and that receives some or all of its television program material from a master head-end in the same metropolitan or regional area. See also head-end and hub.

distribution plant A distribution plant is the hardware of a cable system amplifiers, trunk cable, and feeder lines, attached to utility poles or fed through underground conduits like telephone and electric wires.

distribution system A distribution system is the part of a cable television system used to carry
signals from the head-end to the subscriber’s receivers. The term distribution system is often applied, more narrowly, to the part of a cable television system starting at the bridger amplifiers. See also head-end and amplifier.

dithering Dithering is the illusionary creation of new colors and shades by varying the pattern of dots. In printing, dithering is usually called halftoning and the various different shades of gray are called halftones. Dithering differs from gray scaling. In gray scaling, each individual dot can have a different shade of gray.

DNS See Domain Name Server (DNS).

DOCSIS See Data Over Cable Service Interface Specifications (DOCSIS).

DOCSIS 1.1 DOCSIS 1.1 is a version of the DOCSIS Media Access Control (MAC)-layer protocol standard, which contains quality-of-service (QoS) traffic management functions and BPI authentication extensions.

DOCSIS 2.0 DOCSIS 2.0 is the current version of the DOCSIS standard. DOCSIS 2.0 is backward-compatible with DOCSIS 1.0 and 1.1. It implements advanced physical-layer modulation and S-CDMA, allowing a significantly higher upstream channel capacity, as well as better noise immunity.

DOCSIS modem The Data Over Cable Systems Interface Specifications (DOCSIS) for cable modems were developed by CableLabs and standardized internationally.

Dolby AC-3 Dolby AC-3 refers to the audio encoding format adopted by the Advanced Television Systems Committee (ATSC) for its advanced television audio encoding. Dolby AC-3 is also known as Dolby digital. See also Advanced Television Systems Committee (ATSC).

Domain Name Server (DNS) A domain name server relates an internet domain name—such as www.enabletv.com—to an Internet Protocol (IP) address. See also Internet Protocol (IP).

down conversion A down conversion refers to the heterodyning of an input signal with the output of a local oscillator, resulting in an intermediate frequency that is lower than the incoming signal frequency.

downlink Downlink refers to the transmission of signals from a satellite to a dish or earth station. See also earth station.

download Download refers to the transfer of data from a remote computer or server to a local computer. To the Internet user, downloading means to request a copy of a file from another computer and then receive that file.

downstream Downstream refers to the flow of signals from the cable system control center through the distribution network to the customer. For communication purposes, downstream is associated with transmission (down) to the end-user.

DPI See digital program insertion (DPI).

drop The drop is the cable and hardware from tap to subscriber. See also tap.

drop cable A drop cable is generally 330 feet or less, of coaxial cable, starting at a tap and continuing on to the subscribers connection. See also coaxial cable and tap.

DSL See digital subscriber line (DSL).

DSM-CC See Digital Storage Media-Command and Control (DSM-CC).

DTCP See digital transmission content protection (DTCP).

DTS See decoding time stamp (DTS).

dual cable A dual cable is two independent distribution systems operating side by side, providing double the channel capacity of a single cable. See also channel capacity.

dumb mode Dumb mode refers to a set-top box operating without digital service. A set-top box in dumb mode should, at a minimum, be able to tune to analog video channels.

duplex In a communications channel, duplex refers to the ability to transmit in both directions.

DVB See Digital Video Broadcasting (DVB).

DVB Network A Digital Video Broadcasting (DVB) network is a collection of MPEG-2Transport Stream multiplexes transmitted on a single delivery system. For example, all digital channels on a specific cable system make up a DVB network. See also MPEG-2.

DVI See Digital Visual Interface (DVI).

DVR See digital video recording (DVR).

DVS See Digital Video Subcommittee (DVS).

DWDM See dense wave division multiplexing (DWDM).

dynamic host configuration protocol (DHCP) The dynamic host configuration protocol is an Internet protocol used for assigning network layer, Internet protocol (IP) addresses dynamically to IP hosts. When DHCP is used, whenever a computer logs onto the network, it automatically gets an IP address assigned to it. See also Internet Protocol (IP).

dynamic range Dynamic range refers to the ratio between the greatest signal power that can be transmitted over a multichannel analog transmission system without exceeding distortion or other performance limits, and the least signal power that can be used without exceeding noise, error rate, or other performance limits.

dynamic routing Dynamic routing refers to routing that adjusts automatically to changes in network topology or traffic.

earth station An earth station is a structure—generally referred to as a dish—used for receiving and/or transmitting those electromagnetic signals coming from or going to a satellite.

echo An echo is a wave that has been reflected at one or more points in the transmission medium, with sufficient magnitude and time difference to be perceived in some manner as a wave distinct from that of the main or primary transmission. Echoes may be either leading or lagging the primary wave and appear on the picture monitor as reflections or ghosts. Echoes are also known as reflection. See also ghost.

ECM See Entitlement Control Message (ECM).

ECMAScript ECMAScript is an internationally standardized, general purpose, cross-platform programming language that you can use to provide scripting of events, objects, and actions.

education channel Federal Communications Commission (FCC) rules require cable systems in the top 100 markets to set aside one channel for educational uses, to be available without cost for the developmental period. The developmental period of a cable television system runs for five years from the time that subscriber service began, or five years after the completion of the basic trunk line. See also Federal Communications Commission (FCC).

educational television station(ETV) An educational television station is a non-commercial television station primarily devoted to educational broadcasting.

effects theory The effects theory is a communication theory that proposes that viewers are passive and that television directly affects them.

EIA See Electronic Industries Association (EIA).

electromagnetic spectrum An electromagnetic spectrum is a continuous range of frequencies of
electromagnetic radiation (that is, oscillating electrical and magnetic energy which can travel through space). Within the spectrum, waves have some specified common characteristics. For example, the television broadcast spectrum ranges from 45 to 890 MHz. See also frequency.

electronic commerce (e-commerce) Electronic commerce is the term used to describe commerce that occurs electronically over the Internet.

Electronic Industries Association (EIA) The Electronic Industries Association is a voluntary body of manufacturers that, among other activities, prepares and publishes standards.

electronic program guide (EPG) An electronic program guide is an application that displays  television program information, including program name, start time, and duration. It is literally an onscreen guide that helps make it easier for viewers to choose and/or go to the large number of channels, Pay-Per-View (PPV) events, and shows available particularly in a digital environment. By using the electronic program guide, you can often also pay for events such as Video-on-Demand (VOD). More advanced electronic program guides offer Internet interactivity for browsing, chatting, e-mail, etc. Electronic program guides can also keep track of your favorite channels, offer a reminder service that lets you know when your favorite shows are coming on, restrict access to channels you do not want the kids to see, or offer a television search engine of a sort that can search for types of shows or themes in shows. When the customer starts up his or her set-top box, the electronic program guide probably is what comes up initially. Frequently, the content provider and/or the individual viewer can customize the electronic program guide. See also Pay-Per-View (PPV) and video-on-demand (VOD).

element management system (EMS) The element management system contains software applications used for configuration, performance, and faults from one or more network elements. The element management system is a second layer of management in the telecommunications management network hierarchy.

elementary stream (ES) An elementary stream is a generic term for one of the coded video, coded
audio, or other coded bit streams. One elementary stream is carried in a sequence of Packetized Elementary Stream (PES) packets with one and only one stream_id. See also packet.

embedded subscriber media gateway (E-SMG) An embedded subscriber media gateway is a subscriber media gateway (SMG) with the distinct property that the physical node within the subscriber media gateway also contains a direct media access control (MAC) layer interface to a DOCSIS access network. The only significant functional difference between an E-SMG and a SMG is that the media signaling and streaming function may be capable of directly accessing MAC layer services (traffic management, polling-heartbeats, and authentication functions). See also subscriber media gateway (SMG), MAC, and Data Over Cable Service Interface Specifications (DOCSIS).

embedded-client An embedded-client is a synonym for, and equivalent with, embedded subscriber media gateway. See also embedded subscriber media gateway (E-SMG).

EMM See Entitlement Management Message (EMM).

EMS See element management system (EMS).

emulator An emulator is a hardware or software device that simulates the action of something else. For example, a PC application that is intended to simulate the functionality of the middleware and related set-top box is an emulator.

encapsulation Encapsulation allows one network to send its data over another network’s connections. Tunneling works by encapsulating a network protocol in the packets carried by the second network. See also packet.

encoding Encoding is the scrambling and/or compressing information (data) and/or a signal before transmission. It can be known as a multiplexer. See also multiplexer.

encryption Encryption is a form of encoding transmitted data for security purposes. It normally requires the decryption key to decipher the transmission upon receipt. The level of security depends on the complexity of the key used. See also decryption.

encryption key An encryption key is an alphanumeric (letters and/or numbers) series that enables data to be encrypted and then decrypted so it can be safely shared among members of a network. Some wireless security systems use an encryption key that automatically encrypts outgoing wireless data. On the receiving side, the same encryption key enables the computer to automatically decrypt the information so it can be read.

end system End system is what the end-user on a network uses.

end-to-end In terms of interactive television, end-to-end refers to everything (from the beginning to the end) it takes from the production of the interactive television content, including the broadcasting of the signal to the viewing and interacting by the end-user.

end-user An end-user is the person(s) and/or subscriber(s) who actually uses and/or views the computer, television, or device on the network.

endpoint An endpoint is a destination. It is a place where data is expected and does not need to go any further.

Enhanced TV Enhanced TV can refer to any new service that cannot be delivered with just a regular television. The term Enhanced TV is also used to describe interactive content that is provided for specific television programs.

enhancement Enhancement refers to data sent with the intent of adding value to the user beyond what is possible with the traditional television and channel-changing remote control. Enhancement data can be sent before, during, or after the broadcast. Enhancements may enhance user learning
or enjoyment, may extend the life of a broadcast, or may make the experience more interactive by adding on-demand resources.

Entitlement Control Message (ECM) Entitlement control messages are private conditional access information that specify control words and possibly other stream-specific, scrambling, and/or control parameters. The data does not necessarily have what would be considered more personal information, such as the number of months of service the viewer wants to pay for. See also conditional access and scramble.

Entitlement Management Message (EMM) Entitlement management messages are private conditional access information that specify the authorization level or the services of specific set-top boxes. The information does not address options that activate what movie the viewer wants to see or what times the viewer wants to see it. See also conditional access.

EPG See electronic program guide (EPG).

equal access Equal access refers to the offering of access to local exchange facilities on a non-discriminatory basis.

equalization Equalization is a means of modifying the frequency response of an amplifier or network, thereby resulting in a flat overall response. See also amplifier and frequency.

equalized loss Equalized loss is any loss in cable television systems caused by coaxial cable. Equalized loss is insertion loss of components designed to match cable loss characteristics. See also coaxial cable.

equalizing pulses Equalizing pulses are pulses of one half the width of the horizontal sync pulses that are transmitted at twice the rate of the horizontal sync pulses during the blanking intervals immediately preceding and following the vertical sync pulses. The action of these pulses causes the vertical deflection to start at the same time in each interval, and also serves to keep the horizontal sweep circuits in step during the vertical blanking intervals immediately preceding and following the vertical sync pulse. See also blanking (picture) and vertical blanking interval (VBI).

error rate The error rate is the measure of the performance of a digital transmission system. It can be specified as a bit error rate, as a block error rate, or in other forms such as percent error-free seconds. Bit error rate is the probability of error per bit transmitted. Block error rate is the probability of one or more errors in a specified length block of bits.

errored second An errored second is any one second interval containing at least one bit error.

ES See elementary stream (ES).

E-SMG See embedded subscriber media gateway (E-SMG).

ethernet Ethernet is the most popular Local Area Network (LAN) technology in use today. The Institute of Electrical and Electronic Engineers (IEEE) standard 802.3 defines the rules for configuring an ethernet network. It is a 10Mbps, carrier sense multiple access with collision detection (CSMA/CD) baseband network that runs over thin coax, thick coax, twisted pair or fiber optic cable. See also local area network (LAN), Institute of Electrical and Electronic Engineers (IEEE), coaxial cable, and fiber optics, and carrier sense multiple access with collision detection (CSMA/CD).

ETSI See European Telecommunications Standards Institute (ETSI).

ETV See educational television station (ETV).

European Telecommunications Standards Institute (ETSI) The European Telecommunications Standard Institute (ETSI) is the European equivalent of American National Standards Institute (ANSI). See also American National Standards Institute (ANSI).

event In PSM, an event is a defined value that identifies and provides notification of a specific situation.

exclusivity Exclusivity is the provision in a commercial television film contract that grants exclusive playback rights for the film or episode to a broadcast station in the market it serves. Under the Federal Communications Commission’s (FCC’s) rules, cable operators cannot carry distant signals that violate local television stations’ exclusivity agreements. See also Federal Communications Commission (FCC).

execution engine The execution engine is the portion of OpenCable Application Platform (OCAP) that will provide a full programming environment for performing complex logic and arithmetic operations which the presentation engine (PE) cannot handle alone. In the execution engine, which includes Sun’s JavaTV programming environment, interactive television application developer’s will write interactive applications, in Java, following the OCAP specification. When a cable customer with an OpenCable-compliant set-top box accesses the application through the user interface, the application is transparently downloaded into the set-top box. A Java engine or Java Virtual Machine (JVM) resident in the set-top box decodes the application downloaded over the network, and runs it. See also OpenCable™ Application Platform (OCAP) and presentation engine (PE).

Explorer The Explorer is a digital cable set-top box from Scientific-Atlanta.

extended subsplit An extended subsplit is a frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse path signals come to the head-end from 5 to 42 MHz. Forward path signals go from the head-end from 50 or 54 MHz to the upper frequency limit. See also head-end and coaxial cable.

fading Fading refers to the reduction in signal intensity of one or several of the components of a radio signal, typically caused by the reflective or refractive effects of multiple path.

FAT See forward applications transport (FAT) channel.

favorite channel A favorite channel is a channel that the viewer has added to a logical list that can be scanned.

FCC See Federal Communications Commission (FCC).

F-connector The F-connector is the final piece of hardware—familiar to subscribers—on a drop cable. It is cylindrical with a center pin sticking out, hat plugs into the set-top box, cable ready television, or VCR.

FDD See frequency division duplex (FDD).

FDDI See fiber distributed data interface (FDDI).

FDM See frequency division multiplexed (FDM).

FDMA See frequency division multiple access (FDMA).

feathering Feathering the edge of a graphic image gradually dissipates the edge, making the edge of the image look blurry.

FEC See forward error correction (FEC).

Federal Communications Commission (FCC) The Federal Communications Commission (FCC) is an agency that regulates communications services, including cable television, at the federal level. The FCC was established in 1934 by the Communication Act of 1934.

feeder cable A feeder cable is a coaxial cable that runs along streets within the served area and connects between the individual taps which serve the customer drops. See also coaxial cable.

feeder line The feeder line refers to cable distribution lines that connect the main trunk line or cable to the smaller drop cable.

fiber distributed data interface (FDDI) The fiber distributed data interface (FDDI) is a network based on the use of optical fiber to transmit data at a rate of 100 Mbps.

fiber node A fiber node is a point of interface between a fiber trunk and the coaxial distribution.

fiber optics Fiber optics are the transmission medium that uses glass or plastic fibers versus other, copper-based wires to transmit data or voice signals. Fiber-optic cable offers much greater capacity and transmission speeds than traditional mediums.

field A field is one half of a complete picture (or frame) interval, containing all of the odd or even scanning lines of the picture.

field frequency The field frequency is the rate at which a complete field is scanned, nominally 60 times a second.

file transfer protocol (FTP) The file transfer protocol is a method used to exchange files between computers on a network or the Internet using the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol. It can also be the verb used to describe that transfer. See also Transmission Control Protocol/Internet Protocol (TCP/IP).

filter 1) A filter is a circuit that selects the frequency of desired channels. A filter is used in trunk and feeder lines for special cable services, such as a two-way operation. 2) In general, a filter is used to remove unwanted material from a signal. If you have some high frequencies, such as noise, in with the signal that you really want, then a low-pass filter is used. A low-pass filter passes frequencies below a certain point and stops frequencies above that same point. A high-pass filter does just the opposite—it stops low frequencies and passes the high frequencies.

firewall A firewall is a system that secures a network and prevents access by unauthorized users. Firewalls can be software, hardware, or a combination of both. Firewalls can prevent unrestricted access into a network, as well as restrict data from flowing out of a network.

Flash Flash is Macromedia’s vector graphics-based resizable animation format with navigation and simple interactivity features.

flat loss Flat loss refers to the equal loss at all frequencies, such as caused by attenuators. See also attenuation.

flat outputs Flat outputs refer to the operation of a cable television system with equal levels of all television signals at the output of each amplifier. See also amplifier.

flicker Flicker occurs when the refresh rate of the video is too low. It is the same effect produced by an old fluorescent light fixture. For flicker to disappear, the update rate, or the video frame rate, must be at least 24 frames per second.

flooding Flooding refers to the technique where routing information received by a routing device is sent out through every interface on that device, except the one on which the information was received.

flow The flow is the ordered presentation of various programs, including commercials, news breaks, and so on. It has been argued that certain interactive television services can potentially interrupt and potentially affect the flow of a program or series of programs.

FM See frequency modulation (FM).

FM cable system The FM cable system refers to the FM radio signals offered by the cable system—the cable must be connected to the subscriber’s FM stereo receiver.

forward applications transport (FAT) channel A forward applications transport (FAT) channel is a data channel carried from the head-end to the set-top box in a QAM modulated channel. MPEG-2 transport is used to multiplex video, audio, and data into the forward applications transport channel. See also head-end, quadrature amplitude modulation (QAM), multiplex, and Moving Picture Experts Group (MPEG).

forward channel The forward channel is the direction of radio frequency (RF) signal flow away from the head-end toward the end user. The forward channel is the equivalent to downstream. See also radio frequency (RF) and head-end.

forward data channel The forward data channel is a data channel carried from the head-end to
the set-top box in a modulated channel at a typical rate of 1.5 to 8 Mbps. See also head-end.

forward error correction (FEC) Forward error correction is a technique for regenerating lost data transmissions or error messages. Forward error correction enables the receiver to detect and fix errors to packets without the need for the transmitter to retransmit packets.

forward traffic When signals are transmitted to a subscriber from the head-end, the signals are referred to as the forward traffic. Forward traffic is also known as downstream or forward channel. See also head-end and forward channel.

fragmentation 1) Fragmentation is when broad television audiences break into smaller segments due to multiple viewing choices and niche programming that targets particular demographics.
2) Fragmentation also refers to breaking a packet into smaller units when transmitting over a network that cannot support the original size of the packet. See also demographics and packet.

frame A frame is one complete picture consisting of two fields of interlaced scanning lines. See also field.

frame buffer A frame buffer is the memory used to store a complete frame of video.

frame frequency The frame frequency is the rate at which a complete frame is scanned, which is nominally 30 frames per second.

frame loss Frame loss is the percentage of frames that did not reach the destination.

frame refresh rate The frame refresh rate is the number of complete frames displayed per second. Generally, the number is 50 Hz or 60 Hz per second with analog television, but it can be a lot higher for digital television.

frame set A frame set consists of one downstream, one upstream, and one background frame size.

frame synchronizer A frame synchronizer is the digital buffer that can continuously adjust the signal to counter timing errors.

framework A framework is a micro-architecture that provides an incomplete template for applications within a specific domain.

franchise A franchise is a contract between a cable television company and a municipal government authorizing the company to install cable and offer cable television service within the community.

franchising authority A franchising authority is a governmental body responsible for awarding a
franchise, specifying the terms of a franchise, and regulating its operation. While the franchise authority is usually a local city or county body, some areas are regulated exclusively on the state level.

frequency 1. Frequency refers to the number of times a complete electromagnetic wave cycle occurs in a fixed unit of time, usually one second. The rate at which a current alternates, measured in Hertz, on a telecommunications medium. 2. Frequency also refers to the number of times that a selected person sees or hears an advertisement. Also, the number of times that that person or household is exposed to an advertisement. It can also refer to the number of times an advertisement is run.

frequency division duplex (FDD) Frequency division duplex (FDD) is the simultaneous exchange of uplink and downlink information on different frequencies.

frequency division multiple access (FDMA) Frequency division multiple access technology that separates users by putting each traffic channel on a discrete frequency band.

frequency division multiplexed (FDM) Frequency division multiplexed is a method of transmitting two or more signals by dividing the available transmission frequency into narrow bands and using each as a separate channel.

frequency modulation (FM) Frequency modulation is a common method of transmitting information
over a carrier wave by changing its frequency. See also frequency.

frequency response The frequency response refers to the change of signal gain and phase with
frequency. See also frequency and gain.

front channel The front channel refers to the actual broadcast between the television content provider—which usually means television broadcaster, but not always—and the television viewer. Its characteristics are its high bandwidth—typically, 6 MHz—and its one-way nature. In non-interactive
television systems, the front channel is the only channel as the signal is only going to the viewer. But in interactive television, a back channel is also needed for the return flow of data from the viewer. See also back channel.

front end The front end is the first radio-frequency amplifier stage on a receiver. This is one of the most critical components of the receiver because the sensitivity of the front end dictates the sensitivity of the entire receiver.

front panel display unit The front panel display unit is part of the set-top box that lights up with numbers and/or letters.

front porch The front porch is that portion of the composite picture signal that lies between the leading edge of the horizontal blanking pulse, and the leading edge of the corresponding sync pulse. See also blanking (picture).

FSN See full service network (FSN).

ftp See file transfer protocol (FTP).

full network station A full network station is a commercial television broadcast station that generally carries 85 percent of the hours of programming offered by one of the three major national networks during its weekly prime time hours.

full service network (FSN) Full service networks are cable networks that are intended to provide broadcast television, Internet access, Video-On-Demand (VOD), and voice telephony simultaneously. See also cable network and video-on-demand (VOD).

full-motion video Full-motion video refers to a non-compressed, standard video signal of 30 frames per second and 525 horizontal lines per frame, which is capable of complete action. See also frame.

fully integrated system A fully integrated system is a cable television system designed to take advantage of the optimum amplifier-cable relationship for the highest performance at the lowest cost. Such a system is also suited to the fully automated cable television system concept.

gain Gain refers to a measure of amplification expressed in dB. The gain of an amplifier is usually specified at the highest frequency of operation, for example, at Channel 13 of all-band equipment.

gain control Gain control is an adjustable control that changes the gain of an amplifier. See also amplifier.

gain slope Gain slope is a linear variation in gain from the lowest frequency to the highest frequency.

gateway A gateway is a function or server that acts as a point of interconnection between two different networks. A gateway is a computing machine that is both connected to one or more networks and can pass network information from one network to another.

Gemstar - TV Guide Gemstar - TV Guide, Inc. holds key patents for interactive program guides/electronic program guides. See also electronic program guide (EPG) and interactive program guide (IPG).

ghost A ghost is a shadowy or weak image in the received picture offset either to the left or right of the primary image, the result of transmission conditions which create secondary signals that are received earlier or later than the main or primary signal. A ghost displaced to the left of the primary image is designated as leading and one displaced to the right is designated as following (lagging). When the tonal variations of the ghost are the same as the primary image, it is designated as positive and when it is in reverse, it is designated as negative.

GIF See graphical interchange format (GIF).

gigabyte A gigabyte is about 1.073 billion bytes.

gigahertz (GHz) A gigahertz is one billion cycles of electrical frequency per second.

GOP See group of pictures (GOP).

government channel Federal Communications Commission (FCC) rules require cable systems in the top 100 markets to set aside one channel for local government use, to be available without cost for the developmental period. The development period runs for five years from the time that subscriber service began, or until five years after the completion of the basic trunk line. See also Federal Communications Commission (FCC).

gradient A gradient is a gradual transition of colors. Many metallic images are gradients.

grandfathering Grandfathering refers to exempting cable systems from the federal rules because either they were in existence or operation before the rules, or substantial investments were made in the system construction before the rules. Grandfathering applies to signal carriage, access channels, and the certification process.

graphical interchange format (GIF) The graphical interchange format (GIF) is a common format for image files other than photographs. It is especially suitable for images containing large areas of the same color. GIF files of images are often smaller compared to the same file stored in JPEG format. See also JPEG.

graphical user interface (GUI)

ground communication equipment Ground communication equipment refers to satellite earth station electronic equipment. See also earth station.

group delay Group delay is the difference in transmission time between the highest and lowest of several frequencies through a device, circuit, or system.

group of pictures (GOP) In an MPEG signal, the group of pictures is a group of frames between certain successive frames. Its most substantial use is in television transmission. For that, the group of pictures is typically a group of 12 frames, but that can vary. See also Moving Picture Experts Group (MPEG) and frame.

guard time The guard time is the minimum time allocated between bursts in the upstream referenced from the symbol center of the last symbol of a burst to the symbol center of the first symbol of the following burst. The guard time should be at least the duration of five symbols plus the maximum system timing error.

GUI See graphical user interface (GUI).

GW See gateway.

H.263 H.263 is a standard for variable low bit rate coding of video. H.263 can be better than MPEG-1/MPEG-2 for low resolutions and low bit rates. See also MPEG-1 and MPEG-2.

half duplex Half duplex denotes data transmission that can still occur in two directions over a single line, but only one direction at a time.

halo Most commonly, a halo refers to a dark area surrounding an unusually bright object, caused by the overloading of the camera tube. Reflection of studio lights from a piece of jewelry, for example, might cause a halo effect. With certain camera tube operating adjustments, a white area may surround dark objects.

hardware Hardware refers to the equipment involved in production, storage, distribution, or reception of electronic signals. In cable television, hardware means the head-end, the coaxial cable network, amplifiers, the television receiver, and production equipment, such as cameras and videotape recorders. See also head-end, coaxial cable, and amplifier.

harmonic distortion Harmonic distortion is a form of interference involving the generation of harmonics according to the frequency relationship f=nf1 for each frequency present, where n is a whole number equal to two or more.

harmonic related carrier (HRC) Harmonic related carrier is a method of spacing television channels on a cable television system in exact 6-MHz increments, with all carrier frequencies harmonically related to a common reference.

HAVi HAVi is a software-based on the Institute of Electrical and Electronic Engineers (IEEE) 1394 standard that can make it possible for connections and integration of home entertainment devices, such as set-top boxes with other electronic appliances on a network, particularly a home networking system. See also Institute of Electrical and Electronic Engineers (IEEE).

HBI See horizontal blanking interval (HBI).

HDCP See high-bandwidth digital content protection (HDCP).

HDSL See high-speed digital subscriber line (HDSL).

HDTV See high definition television (HDTV).

HDTV quality ITU-R Recommendation 1125 defines HDTV quality as the delivery of a television picture which is subjectively identical with the interlaced HDTV studio standard. See also high definition television (HDTV) and International Telecommunications Union (ITU).

head-end The head-end is the control center of a cable television system, where incoming signals are amplified, converted, processed, and combined into a common cable along with any original cablecasting, for transmission to subscribers. The system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors, and other related equipment. See also cablecasting, antenna, and amplifier.

head-end router The head-end router is the computer, at the cable head-end, responsible for gateway operations between the head-end and the internet.

header A header is the protocol control information located at the beginning of a protocol data unit.

helpful applications Helpful applications are small software programs linked to your browser that help you to see and listen to video and sound clips.

hertz (Hz) A hertz is a unit of frequency equivalent to one cycle per second. See also Megahertz (MHz) and gigahertz (GHz).

HFC See hybrid fiber coax (HFC).

high band High band refers to channels 7 through 13.

high-bandwidth digital content protection (HDCP)The high-bandwidth digital content protection (HDCP) specification was developed for protecting digital entertainment content that uses the Digital
Visual Interface (DVI). HDCP encrypts the transmission of digital content between the video source or transmitter—such as a computer, DVD player, or set-top box—and the digital display, or receiver—such as a monitor, television, or projector. See also Digital Visual Interface (DVI).

high definition television (HDTV) High definition television refers to a television signal with greater detail and fidelity than the current television systems used. The United States currently uses a system called National Television Systems Committee (NTSC). HDTV provides a picture with twice the visual resolution in both the horizontal and vertical dimensions and a picture aspect ratio of 16:9 as well as CD-quality audio. See also National Television Systems Committee (NTSC) and aspect ratio.

high frequency High frequency is used to refer to the entire subsplit (5-30 MHz) and extended subsplit (5-42 MHz) band used in reverse channel communications over the cable television network. See also Ultra High Frequency (UHF) and Very High Frequency (VHF).

high Q High Q is a fiber circuit with a great deal of selectivity.

high return A high return refers to the frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the head-end above the downstream passband. See also coaxial cable and head-end.

high-speed digital subscriber line (HDSL) The high-speed digital subscriber line (HDSL) uses the existing copper infrastructure of the telephone companies. HDSL offers video and dat transmission rates of 1.5 Mbps up to 12,000 feet. See also DSL.

high speed serial interface (HSSI) High speed serial interface is a standard for high-speed serial communications at up to 52 Mbps over Wide Area Networks (WAN). See also Wide Area Network (WAN).

high split High split is when the upstream frequencies are 5-150/174-750 MHz. This split provides the greatest amount of return path.

high VHF band High VHF band is a part of the frequency band that the Federal Communications Commission (FCC) allocates to VHF broadcasting, including channels 7 through 13, or 174 through 216 MHz. See also Federal Communications Commission (FCC) and Very High Frequency (VHF).

Home AV Interoperability (HAVi) See also HAVi, which is the more common name.

home networking Home networking refers to connecting computers and other devices/appliances with processors in the home to one central hub (computer) in the home. See also hub.

homes passed Homes passed is used to describe the total number of homes that have the
potential for being hooked up to the cable system.

horizontal (hum) bars Horizontal (hum) bars are relatively broad horizontal bars, alternately black and white, which extend over the entire picture. They may be stationary, or may move up or down. Horizontal (hum) bars are sometimes referred to as a venetian blind effect and are caused by approximate 60-cycle interfering frequency, or one of its harmonic frequencies.

horizontal blanking interval(HBI) The horizontal blanking interval is an unused gap in a television signal that occurs before each line of a picture. This is not the same as the vertical blanking interval. See also vertical blanking interval (VBI).

host adapter A host adapter is the computer circuit that not only controls the hard drive, but processes data going in and out of the drive.

house drop A house drop is the coaxial cable that connects each building or home to the nearest feeder line of the cable network. See also coaxial cable and feeder line.

HRC See harmonic related carrier (HRC).

HSSI See high speed serial interface (HSSI).

HTML See Hypertext Markup Language (HTML).

HTTP See Hypertext Transfer Protocol (HTTP)

HTTPS See Hypertext Transfer Protocol Secure (HTTPS).

hub A hub is a device used to connect segments of a network. A hub offers bandwidth on demand to shared resources versus being fixed to all accessible ports. A hub is a signal distribution point for part of an overall system. Larger cable systems are often served by multiple hub sites, with each hub in turn linked to the main head-end with a transportation link such as fiber optics, coaxial supertrunk, or microwave. A hub may also be a hardware device that interconnects computers on a Local Area Network (LAN) and acts as a central distribution point for the communications lines. See also head end, fiber optics, and local area network (LAN).

hue Hue corresponds to color in everyday use; that is, red, blue, etc. Black, white, and gray do not have hue.

hum modulation Hum modulation refers to the undesired modulation of the television visual carrier by the fundamental or low-order harmonics of the power supply frequency, or other low-frequency disturbances. See also modulation.

hybrid fiber coax (HFC) Hybrid fiber coax is a type of network that has both copper coaxial cables and fiber-optic cables. Cable television is evolving into cable telecommunications. Cable multiple system operators (MSOs) throughout the world are upgrading coaxial cable systems to hybrid fiber coax cable networks to deliver high-speed data and Internet service, cable telephony or competitive local exchange service, and digital multimedia services, along with multiple channel television. See also coaxial cable, fiber optics, and multiple systems operator (MSO).
Hypertext Markup Language (HTML) HTML is the language used to create and display web documents. It uses tags to identify the components of a document—text, graphics, and multimedia and how those components should behave.

Hypertext Transfer Protocol (HTTP) HTTP is the standard for exchanging files—text, graphics, and multimedia—on the World Wide Web.

Hypertext Transfer Protocol Secure (HTTPS) HTTPS is an extension of HTTP to enable security on a web site. HTTPS encrypts and decrypts your page requests and the data returned to you by a web server. See also Hypertext Transfer Protocol (HTTP).

ICG See interactive cable gateway (ICG).

ICMP See internet control message protocol (ICMP).

icon Icons are small pictures that correlate to actions offered by a computer program, application, or operating system. With a pointing device—such as a mouse or a remote control—you can initiate the activity in your operating system or application that is associated with that icon.

ICN See integrated community network (ICN).

IDE See integrated device electronics (IDE).

IDT See improved definition television (IDT).

IDVD Player See integrated digital video disk (IDVD) player.

IEC See International Electrotechnical Commission (IEC).

IEEE See Institute of Electrical and Electronic Engineers (IEEE).

IEEE 802.3 IEEE 802.3 is a term that is sometimes used interchangeably with Ethernet, because it is the standards title the IEEE gave Ethernet.

IEEE 1284 parallel port IEEE 1284 parallel port is a very high-speed port (connection) to a printer. It is approximately 40 times faster than the standard parallel ports found in desktops and laptop computers.

IEEE 1394 IEEE 1394 is a high performance serial connection, which is also known as FireWire Bus. It is a high-speed serial digital interface standard enabling data communication between the digital set-top box and DVD players or D-VHS records. Transmission speed is scalable from approximately 100 Mbps to 400 Mbps. It was originally developed by Apple for use in Local Area Networks (LANs) and connections between digital video recorders (DVRs), personal computers, and certain other electronic devices, which as it turns out includes set-top boxes. See digital video recording (DVR) and local area network (LAN).

IETF See internet engineering task force (IETF).

I frames I frames are one of the three types of frames that are used in MPEG-2 coded signals. The other two are B frames and P frames. It is MPEG-2 still pictures. See also MPEG-2.

IKE See internet key exchange (IKE).

illegal colors Illegal colors refer to colors that force a color system to go outside its normal bounds. Usually, illegal colors are the result of electronically painted images rather than direct camera outputs.

image map Image maps are graphic images containing a number of links that you can click on to go somewhere else.

impedance Impedance refers to the resistance a wire offers to a change in current as the current runs down the length of the wire. Impedance is measured in ohms.

improved definition television (IDT) Improved definition televisions contain circuitry for improved use of the information in current broadcast signals.

impulse noise Impulse noise refers to short bursts of high-level noise such as that resulting from the coupling of transients into a channel. Typical sources of such noises are lightning and transients from switching systems. Impulse noise—which sounds like a click—is not particularly detrimental to voice
communications, but it can be detrimental to data communications.

impulse pay-per-view (IPPV) Impulse pay-per-view (IPPV) is a movie rental service similar to pay-per-view (PPV). However, IPPV allows the customer to purchase the right to view the movie or event through an on-screen interface. See also Pay-Per-View (PPV).

in-band channels In-band channels provide service-related broadcast information, subscriber
tunable channels, and hidden channels.

in-band data QAM An in-band data QAM is a QAM that supports the 10Mbps data circuit that the DNCS uses to broadcast in-band data to the set-top box. See also quadrature amplitude modulation (QAM).

incremental related carriers (IRC) Incremental related carriers is a method of spacing National Television Systems Committee (NTSC) television channels on a cable television system in which all channels—except 5 and 6—correspond to the standard channel plan. These are used to reduce composite triple beat distortions. See also National Television Systems Committee (NTSC) and composite triple beat (CTB).

independent Independent refers to a television station that has no exclusive affiliation that obliges it to carry programs from one of the national networks. Indendent also refers to an individually-owned and operated cable television system, not affiliated with a Multiple Systems Operator (MSO).
See also multiple systems operator (MSO).

independent operator An independent operator is an individually owned and operated cable television system, not affiliated with a Multiple Systems Operator (MSO). See also multiple systems operator (MSO).

inductance Inductance refers to the ability of a device to store energy in the form of a magnetic field.

inductor An inductor is an electronic component designed to provide a controlled amount of inductance.

industry standard architecture (ISA) Industry standard architecture (ISA) is an interface standard for connecting hardware expansion cards to a computer. The typical ISA connection is a slot, or edge-card connector, on the computer’s motherboard allowing devices such as sound cards and telephone modems to be plugged in to the computer.

infomercial An infomercial is a commercial—usually 90 seconds or more in length—designed to supply information about a product or service rather than to present a specific sales message.

inline package An inline package refers to the housing—for amplifiers or other cable television components—designed for use without jumper cables. The cable connectors on the ends of the housing are in line with the coaxial cable. See also coaxial cable and amplifier.

insertion loss Insertion loss refers to the additional loss in a system when a device such as a directional coupler is inserted. Insertion loss is equal to the difference in signal level between input and output of such a device.

Institute of Electrical and Electronic Engineers (IEEE) IEEE is a professional organization of electrical, electronics, and computer engineers. Among its many activities, it sets standards. Refer to www.ieee.org for more information.

institutional network An institutional network is a network that is operated with a cable television system. An institutional network is designed to satisfy the needs of schools, businesses, or government.

integrated community network(ICN) An integrated community network is a shared public network for communication services to support applications such as distance learning, remote court procedures, and telemedicine.

integrated device electronics (IDE) Integrated device electronics refers to a disk drive interface that is the standard today. It eliminates the need for a separate expansion card for helping to operate the hard drive as the necessary electronics are built into the actual disk drive.

integrated digital video disk (IDVD) player An integrated digital video disk (IDVD) player is a type of Internet appliance. It is hardware that looks much like a larger DVD player, but it has an internet browser, a DVD player and chip, an Internet connection, some additional RAM, a connector, and a keyboard. You view the output of an IDVD player on your television set.

integrated receiver transcoder (IRT) An integrated receiver transcoder is a satellite receiver that also decodes the encrypted digital signal. An IRT outputs up to 12 clear MPEG-2 data streams. See also Moving Picture Experts Group (MPEG).

integrated services digital network (ISDN) The integrated services digital network refers to technology that offers digital transmission rates up to 128 kbps over an existing twisted pair copper telephone line. It is a digital telephone line that can be used for voice, fax, and data communications like a regular telephone line, but can transport data five times faster (or more) than a 28.8Kbps V.34 modem and allow you to talk on the phone to one person while sending data to another.

Integrated TVs Integrated TVs offers multiple features, such as PC components, high definition monitor, HDTV reception, hard drive, remote keyboard, etc. Integrated TVs are also known by other names, including PCTVs, computer televisions, integrated smart televisions, etc. See also high definition television (HDTV).

integration Integration refers to combining computer functions with television viewing via a television tuner card and other required hardware and software. See also Integrated TVs.

interactive advertising Interactive advertising most often takes the form of television commercials that offer isolated link areas—which may be referred to as triggers, rollovers, or hot spots—that are viewed along with the television program. Viewers can click on these links using a control device such as a remote control, mouse, or keyboard, and experience more of the commercial than those who see the commercial without these enhancements. An example is when a commercial is aired and a link to the advertiser’s web site is presented as part of the commercial, the viewer then could immediately click on the link(s) on the advertisement to go there. Viewers of that same advertisement, who do not have interactive television capacity, would not see those link areas. Interactive advertising is expected to be among the fastest growing segments of interactive television.

interactive cable Cable systems that have the technical ability to let subscribers communicate directly from their television sets to a computer at the system head-end using special converters and regular cable lines are referred to as interactive cable systems. Viewers can take advantage of services like movies-on-demand (MOD) and video-on-demand (VOD), as well as participate in targeted, interactive advertising from their home. See also video-on-demand (VOD).

interactive cable gateway (ICG) The interactive cable gateway refers to the conversion point from the core network to the hybrid fiber coaxial (HFC) transport network. Core connections are terminated and MPEG-2 transport streams are reconstructed. See also MPEG-2 and hybrid fiber coax (HFC).

interactive channel browser An interactive channel browser, or channel browser, refers to a screen that comes up on the television screen and contains thumbnail size—roughly the size of big stamps—views of what is on each channel at that moment. The viewer, using the remote control can choose which channel he or she wishes and the sound and other channel information will come on for that channel.

interactive multi-camera-anglesporting event Interactive, multi-camera-angle sporting events is an enhanced feature of some television systems that allows you to choose the camera angle from which you want to view an event.

interactive program guide (IPG) An interactive program guide is similar to an electronic program guide (EPG), but with increased interactive features, such as allowing users to sort through onscreen television listings by time, or channel, or themes, like children’s shows, and program a VCR or television directly from within th guide. See also electronic program guide (EPG).

interactive television (iTV) Interactive television refers to a combination of television and interactive
content and enhancements. Interactive television provides a richer entertainment experience as well as information, blending traditional television viewing with some of the interactivity of a PC. Interactive television features can include richer graphics, Internet access, email, chat, instant messaging, home shopping, home banking, interactive games, on-demand services such as weather and financial information, pay-per-view (PPV), and video-on-demand (VOD). See also Pay-Per-View (PPV) and video-on-demand (VOD).

interchangeability Interchangeability refers to the ability to exchange tapes between different
manufacturers’ videotape recorders with no appreciable degradation of playback image.

interconnect Interconnect refers to two or more cable systems distributing a programming or commercial signal simultaneously.

interdiction Interdiction is a method of receiving television signals by jamming unauthorized signals but having all other signals received in the clear. Because the jamming is accomplished outside the home, it does not require a set-top box in the home.

interface The interface is literally the appearance of the information, data, images, etc. that you see on a computer screen or interactive television screen. Designing interfaces that are easy to use and understand is important.

interference Interference refers to energy which tends to interfere with the reception of the desired signals, such as fading from airline flights, radio frequenc (RF) interference from adjacent channels, or ghosting from reflecting objects such as mountains and buildings. See also ghost and radio frequency (RF) interference.

interference rejection The reception of unwanted signals is interference; smart antenna system reject interference by nulling the unwanted signal through phase shifting. Smart antenna systems also reduce interference to other systems by nulling the transmitted signal in the direction of the unintended receiver.

interlaced scanning (interlace) Interlaced scanning refers to a scanning process in which each adjacent line belongs to the alternate field.

interlacing Interlacing refers to the television display format, where horizontal lines of pixels are illuminated in an alternating pattern rather than sequentially. See also pixel.

International Electrotechnical Commission (IEC) The International Electrotechnical Commission is an international standards body.

International Organization for Standardization (ISO) The International Organization for Standardization is an international standards body, commonly known as the International Standards Organization.

International Telecommunications Union (ITU) The International Telecommunications Union is a United Nations organization that establishes standards for telecommunications devices, like ISDN hardware, modems, and fax machines. See also integrate services digital network (ISDN).

internet The internet is a series of interconnected local, regional, national, and international networks, linked using Transmission Control Protocol/Internet Protocol (TCP/IP). The Internet is accessible via telephony wires, hybrid fiber coaxial networks and by satellite. See also hybrid fiber coax (HFC) and Transmission Control Protocol/Internet Protocol (TCP/IP).

Internet appliance An internet appliance is a computer intended primarily for Internet access. An internet appliance is simple to set up and usually does not support installation of third-party software. These computers generally offer customized web browsing, touch-screen navigation, email services, entertainment, and personal information management applications. An internet appliance can be Wi Fi enabled or it can be connected via a cable to the local network. See also Wi-Fi.

internet control message protocol (ICMP) The internet control message protocol is an internet network layer protocol.

internet engineering task force (IETF) The internet engineering task force is the body responsible for, among other things, developing standards used in the Internet.

internet key exchange (IKE) The internet key exchange is a method standardized by the Internet engineering task force (IETF) for exchanging security keys. See also internet engineering task force (IETF).

Internet Protocol (IP) The Internet Protocol refers to the network layer (layer 3) of the Open Systems Interconnect (OSI) Internet protocol, providing connectionless datagram service. It describes the computer network protocol—analogous to written and verbal languages—that all machines on the Internet must know so that they can communicate with one another. It also is the network layer of Transmission Control Protocol/Internet Protocol (TCP/IP) which controls the flow of data packets. See also Open Systems Interconnection (OSI) and Transmission Control Protocol/Internet Protocol (TCP/IP).

internet service provider (ISP) An internet service provider is a company that sells Internet access.

IP See Internet Protocol (IP).

IP address An IP address is a 32-bit number that uniquely identifies a computer on the Internet to other host computers. It is used to route data packets to their intended destination. IP addresses are displayed in the form of four groups of numbers from 0 to 255 separated by dots—for example, 24.64.231.1.

IPPV See impulse pay-per-view (IPPV).

IP telephony See voice-over-internet potocol (VoIP).

IPG See interactive program guide (IPG).

IRC See incremental related carriers (IRC).

IRT See integrated receiver transcoder (IRT).

ISA See industry standard architecture (ISA).

ISDN See integrated services digital network (ISDN).

ISDN digital subscriber line (IDSL) An ISDN digital subscriber line (IDSL) is a 128Kbps standard that provides low-cost, dedicated 128Kbps data service using telephone lines and central office switch facility space leased from the telephone company. It uses standard Point-to-Point ISDN signaling techniques to link the customer to the central office head-end. See also integrated services digital network (ISDN).

ISO See International Organization for Standardization (ISO).

ITU See International Telecommunications Union (ITU).

iTV See interactive television (iTV).

jabber Jabber refers to the uncontrolled transmission in a network of oversized
frames. It is caused by a faulty device. See also frame.

Java Java is a cross-platform language that processes on the client side (client browser). In many ways, Java is an efficient programming language. Java can run in anything that has a processor such as microwave ovens, cars, and old slow computers. In addition, it only needs to be written once for
any computer. Thus, Macintosh computers can use the same Java software as a PC. Java is an integral part of the interactive television revolution.

Java Abstract Window Toolkit (AWT) Java AWT is a large collection of classes for building graphical user interfaces (GUIs) in Java. See also Java.

JavaScript JavaScript is a scripting language developed by Netscape and Sun Microsystems to enable Web page designers to design interactive sites. Although it shares many of the features and structures of the full Java language, it was developed independently. JavaScript can interact with HTML source code, better enabling Web authors to spice up their sites with dynamic content. See also Hypertext Markup Language (HTML).

JavaTv application programming interface (API) JavaTV application programming interface (API) allows consumers—through a set-top box or digital television that supports the JavaTV API—to receive interactive television content such as enhanced television, video-on-demand (VOD), electronic program guides (EPGs), and interactive multi-camera-angle sporting events. See also Enhanced TV, electronic program guide (EPG), interactive multi-camera-angle sporting events, and video-on-demand (VOD).

jitter Jitter is a variance in latency. See also latency.

Joint Picture Experts Group (JPEG) JPEG is a standard for the compression of still graphics. It is usually used for pictures.

JPEG See Joint Picture Experts Group (JPEG).

jumper cable A jumper cable is a short length of flexible coaxial cable used in older cable television systems to connect the system’s coaxial cable to amplifiers or other cable television components. See also coaxial cable and amplifier.

Ka-band Ka-band refers to the 33 to 36 GHz (gigahertz) frequency band used by satellites. Orbital location of two-way satellite data services provided by Direct Broadcast Satellite (DBS) companies.

kernel The kernel is the heart of the operating system. It manages the vital portions of the operating system, including memory, files, application programs, and peripherals.

kerning Kerning refers to the horizontal spacing between the letters in a word.

KiloBits per second (Kbps) One Kbps is equal to 1000 bits transmitted in one second.

kinescope recording Kinescope recording is the film recording made by a motion picture camera designed to photograph a television program directly from the front of a television tube.

Ku-band The Ku-band is the group of microwave frequencies from 12 to 18 GHz, and the band of satellite downlink frequencies from 11.7 to 12.2 GHz.

LAN See local area network (LAN).

last mile The last mile refers to the last physical mile between a central office and a customer in a telephone network or a node and a customer in a cable television network. Last-mile distances generally range from zero miles to three miles.

last mile framing Last mile framing refers to the data encapsulation and transmission protocols used between the consumer premises and the head-end. Framing techniques include asynchronous transfer mode (ATM), MPEG, and IP. See also Moving Picture Experts Group (MPEG), asynchronous transfer mode (ATM), and Internet Protocol (IP).

latency Latency is the time, expressed in quantity of symbols, taken for a signal element to pass through a device.

layer In an operating system, layers are specific groups of software packages in a model at the same level of abstraction. Each layer within the operating system performs functions for the layers above it.

LDS See local distribution system (LDS).

leading Leading is the vertical spacing between lines of text.

leapfrogging Leapfrogging refers to the cable television operators’ practice of skipping over one or more of the nearest television stations to bring in a further signal for more program diversity. Federal Communications Commission (FCC) rules establish priority for carrying stations that lie outside the cable systems service area. See also Federal Communications Commission (FCC).

leaseback Leaseback is the practice by telephone companies of installing and maintaining cable television distribution systems, and leasing the facilities back to separate contractors to actually operate the system.

leased access On some systems, leased access refers to a public access channel for which programmers pay a fee for use and are permitted to sell commercial time in their programming. This is also known as a leased channel.

least significant bit (LSB) The least significant bit is the bit that has the least value in a binary
number or data byte. In written binary number form—such as 1010—the least significant bit is the bit furthest to the right.

legal colors In National Television Systems Committee (NTSC) video, the legal colors are those colors that reproduce on your television screen. Some computer generated colors are called illegal, because they do not display correctly on most televisions. See also National Television Systems Committee (NTSC).

letterbox Letterbox is the alternative to pan and scan for displaying 16:9 aspect ratio programs—such as movies—on a standard 4:3 aspect ratio screen. While pan and scan matches the height of the movie image with the height of the screen, letterbox format involves matching the widths of movie and television screens. The result is that the movie image has large blank spaces above and below it on the television screen, the letterbox format does not lose any of the movie image content (unlike pan and scan), but it does give a smaller image, and therefore a small (effective) screen resolution. Side panels and pillarboxes are in the same category. See also aspect ratio and pan and scan.

Liberate Liberate is a company that provides middleware software for set-top boxes and back-end software to support set-top box interactivity. See also middleware.

line In television systems, the scanning of a television picture is performed in a series of horizontal lines. In an interlaced scan, a frame consisting of the odd-numbered lines is followed by a frame consisting of the odd-numbered lines is followed by a frame consisting of the even-numbered lines. The two frames together make up a complete picture. The number of lines is a convenient measure of the resolution of a television picture; the larger the number of lines, the greater the resolution. Standard analog television formats have 525 (NTSC) or 625 (PAL, SECAM) lines in total. HDTV systems may have 1000+ lines. Although the total number of lines is usually quoted, a better measure of resolution is the number of visible lines. See also analog, frame, National Television Systems Committee (NTSC) and Phase Alternating Lines (PAL).

line 21 Line 21 refers to the television resolution horizontal line selected by the Electronic Industries Association (EIA) as a location for data to carry television closed captions. See also Electronic Industries Association (EIA) and closed captioning.

line frequency Line frequency refers to the number of horizontal scans per second, nominally 15,750 times per second.

linear video Linear video refers to non-interactive television. In most cases, it is a television program that the broadcasters and producers do not want you to leave.

Link Layer Control (LLC) The LLC network protocol sublayer is the part of the data link layer that uses the services of the Medium Access Control (MAC) Layer to provide services to the network layer.

linux Linux is a type of Unix operating system. Linux is attracting attention for its use as an operating system in set-top boxes.

live streaming Live streaming is used to refer to streaming media that is broadcasted to many people at a set time.

LLC See Link Layer Control (LLC).

LMDS See local multipoint distribution system (LMDS).

LNA See low noise amplifier (LNA).

LNB See low noise block converter (LNB).

loader A loader is a computer program that loads another program into memory. All operating systems include loaders. When the user opens a program, the loader loads it and then transfers control to the program.

local area network (LAN) A local area network (LAN) is a collection of computing equipment at a single location—for example, an office building or campus—that communicate with each other to share resources and information, such as disk storage and files, printers, and email. See also Wide Area Network (WAN).

local distribution system (LDS) A local distribution system (LDS) is a wide band microwave system or cable system that can transport a number of television signals simultaneously. It is used to connect cable system head-ends. See also head-end.

local multipoint distribution system (LMDS) A Local Multipoint Distribution System uses microwave frequencies to send and receive broadband frequencies. See also broadband.

local origination Local origination refers to programming developed by an individual cable television system specifically for the community it serves.

local signals Local signals refer to the television signals that are received at locations that are within the station’s predicted Grade B contour. Cable systems must carry all commercial local signals in their areas. See also predicted Grade B contour.

Logical Link Control (LLC) procedure In a local area network (LAN) or a metropolitan area network (MAN), the Logical Link Control is that part of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared.

lossy compression Lossy compression is a term graphics programmers use to refer to a technique of shrinking file sizes by giving away some precision of detail JPEG is the most common of these. By reducing the quality of a picture when you save it, you can make the file size smaller. Many pictures can take a lot of loss of fine detail before it becomes noticeable on a Web page. Most video compression technologies, such as MPEG, use a lossy technique. See also compression, JPEG, and Moving Picture Experts Group (MPEG).

low band Low band refers to television channels 2 through 6. See also mid band.

low noise amplifier (LNA) A low noise amplifier is a low noise signal booster used to amplify the
weak signals received on a satellite antenna. Low noise amplifiers are usually found in the receiver front ends. See also amplifier.

low noise block converter (LNB) A low noise block converter is usually mounted at the focal point of the dish of a satellite and used to amplify and convert satellite signals into frequencies sent to the receiver. See also satellite.

low pass filter (LPF) A low pass filter replaces the regular filter—used for one-way transmission—on a drop, and enables a subscriber to have two-way service. The low pass filter allows low frequencies to pass, but blocks out higher frequencies. See also drop.

low power television Low power television is a broadcast medium that is similar to commercial television, but limited in broadcast coverage area by its low power signal.

low split Low split is when upstream frequencies are assigned below 54Mhz.

low VHF band The low VHF band is the part of the frequency band allocated by the Federal Communications Commission (FCC) for VHF broadcast
television, including television channels 2 through 6, or 54 through 108 MHz. See also Federal Communications Commission (FCC), low band, and Very High Frequency (VHF).

LPF See low pass filter (LPF).

LSB See least significant bit (LSB).

luminance signal The luminance signal is that portion of the National Television Systems Committee (NTSC) color television signal which contains the luminance or brightness information. See also National Television Systems Committee (NTSC).

MAC See multiplexed analog components (MAC).

macroblock A macroblock is the basic unit used for motion compensated prediction in the MPEG-2 standard. Macroblocks are sometimes referred to as slices or blocks. See also MPEG-2.

macrovision Macrovision is a signal recorded on a video tape in a manner that the tape
can be played but not copied.

management information base (MIB) A management information base is an SNMP-defined data structure used for storing and retrieving information to and from network elements. See also Simple Network Management Protocol (SNMP).

masked channel A masked channel is a channel that has been excluded from channel up/down scanning and/or the IPG display. For example, the DMS services may mask their many content-carrying channels from both channel up/down scanning and the IPG, while allowing them to be directly selected or used as favorites. See also interactive program guide (IPG).

master antenna television (MATV) Master antenna television is a broadcast receiving station that uses one or more centrally located UHF and/or VHF antennas that relay their signals to many televisions in an isolated area, such as a local apartment or condominium complex or group-housing complex. See also Ultra High Frequency (UHF) and Very High Frequency (VHF).

master head-end A master head-end collects television program material from various sources by
satellite, microwave, fiber, and other means, and distributes this material to distribution hubs in the same metropolitan or regional area. A master head-end may also perform the functions of a distribution hub for customers in its own immediate area. See also head-end and distribution hub.

MATV See master antenna television (MATV).

maximum service television (MSTV) The Association for Maximum Service Television, Inc. (MSTV) is a national association of local television stations that was launched in 1956. MSTV is dedicated to preserving and improving the technical quality of free, universal, community-based television service to the American public. Over the years, MSTV has prevented interference and dilution of the Federal Communications Commission (FCC) technical standards for television. See also Federal Communications Commission (FCC).

maximum transfer unit (MTU) A maximum transfer unit is one way to measure data being transferred. This is typically the largest packet size that your computer will try to send.

M-bone See multicast backbone.

Mbps Mbps stands for megabits per second, or 1024 kilobits per second.

MCNS See multimedia cable network system (MCNS).

MCPC See multiple channel per carrier (MCPC).

mean time to repair (MTTR) In cable television systems, the mean time to repair is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored. See also radio frequency (RF).

media The term media refers to anything that distributes information.

media access control (MAC) The media access control (MAC) sublayer is the part of the data link layer that supports topology-dependent functions and uses the services of the physical layer to provide services to the Logical Link Control (LLC).

media access control address (MAC address) The media access control (MAC) address is the unique hardware number assigned to network connection devices such as your computer’s network card. The MAC address is written as a series of six pairs of characters divided by hyphens—for example, 00-OF-3D-50-A1-98, and is also referred to as the hardware address or adapter address. See also media access control (MAC).

media access control procedure (MAC procedure) In a subnetwork, the MAC procedure is that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the data exchange between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium. See also media access control (MAC).

media access control service access point (MSAP) The media access control service point (MSAP) is the conceptual binding of a media access control (MAC) layer service provider to the protocol entities—that is, data link layers—above it. See also media access control (MAC).

media access control sublayer (MAC sublayer) The media access control (MAC) sublayer is the part of the datalink layer that supports topology dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer. See also media access control (MAC).

media appliance A media appliance is a type of set-top box environment that can offer video, text, audio, graphics, and streaming media via Internet connectivity. Media appliances typically also offer one or more interactive user interfaces.

media center A media center is a type of set-top box environment that can offer video, text, audio, graphics, streaming media, Video-On-Demand (VOD), music downloads and games, content sharing, and videoconferencing via network—which may even be the Internet—connectivity. Media centers also offer one or more interactive user interfaces and more typically are in the cable television category. All services may not come with the customer’s original set-top box, but may be added to their television system with the addition of another set-top box. See also video-on-demand (VOD).

media converters Media converters can connect servers, hubs, switches, and even desktops to network resources and can be accessed remotely. Media converters can be standalone or a component of a larger system. They can be used as part of enterprise networks and telecommunications applications such as Ethernet. Media converters may be used simply to convert copper to fiber optic cabling, and vice versa. Media converters can also enable various types of cables to be installed into a common media hub or switch. See also fiber optics, hub, server, and switch.

media gateway A media gateway terminates switched circuit network facilities, such as trunks and loops, packetizes the media stream, if it is not already packetized, and delivers packetized traffic to the packet network. It performs these functions in the reverse order for media streams flowing from the packet network to the switched circuit network facility.

Megahertz (MHz) One Megahertz represents one million cycles per second. It is the speed that microprocessors run at—which is called the clock speed. For example, a microprocessor that runs at 200 MHz executes 200 million cycles per second.

memory The term memory is most often used to indicate physical data storage areas that are in the form of computer chips. The word storage is used for a physical data storage area existing on disks and tapes. Storage areas keep the data put in them after the computer is turned off. A computer’s physical memory is called its main memory or RAM. However, there are computer chips that store inputted information whether the computer is on or not. The two best known memories are:
◆ Read Only Memory (ROM), which typically stores instructions used to start up the computer
◆ Programmable Read Only Memory (PROM), which is a memory chip on which you can store a program

menubar Menubars can be used in interactive television interfaces. Menubars are the top instructional line on a page in Windows or a program run on Windows. The commands on this line contain only text.

metadata 1. Metadata describes the characteristics of an asset. It includes attributes that are inherent in the content of the asset, such as the format, duration, size, or encoding method. Metadata is determined at the time the asset is created and does not change. Metadata is extensible and consists of keyword-value pairs. Providers may create application-specific keywords. 2. Metatdata also refers to the information downloaded over the Internet that helps you sort through and selectively view or listen to just the good parts of your previously recorded and stored broadcasts. method 1. A method refers to regular and systematic way of accomplishing a task. It also refers to the detailed, logically ordered plans or procedures followed to accomplish a task or attain a goal. 2. In UML 1.2, a method is the implementation of an operation, as well as the algorithm or procedure that affects the results of an operation

MHEG-5 See Multimedia and Hypermedia information coding Experts Group (MHEG-5).

MHP See Multimedia Home Platform (MHP).

MIB See management information base (MIB).

microprocessor The microprocessor is a computer processor on a microchip. When the computer is turned on, the microprocessor first gets its instructions from the Basic Input/Output System (BIOS). After that, either the BIOS or the operating system that the BIOS loaded into computer memory, and/or a computer application, gives the microprocessor instructions on how to perform.

micro-reflections Micro-reflections are echoes in the forward transmission path due to departures from ideal amplitude and phase characteristics.

microsecond A microsecond is one millionth of a second.

microwave A microwave is a high frequency radio wave used for telecommunications transmission. Microwaves are line-of-sight, point-to-point transmission of signals at high frequency, usually above 890 MHz. Many cable television systems receive some television signals from a distant antenna location with the antenna and the system connected by microwave relay. Microwave frequencies require direct line-of-sight to operate. Trees and buildings distort or block the signal.

microwave oscillator A microwave oscillator is a device used to generate a microwave signal. It consists of two parts:
◆ a resonator to control the frequency of the microwave signal
◆ an active device to generate the power
mid band The mid band refers to the part of the frequency band that lies between television channels 6 and 7, received by the Federal Communications Commission (FCC) for air, maritime and land mobile units, FM radio, and aeronautical and maritime navigation. Mid-band frequencies, 108 to 174 MHz, can also be used to provide additional channels on cable television systems. See also Federal Communications Commission (FCC) and low band.

mid split A mid split is a frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the head-end from 5 to 108 MHz. Forward path signals go from the head-end from 162 MHz to the upper frequency limit. The duplex crossover band is located from 108 to 162 MHz. See also coaxial cable.

middleware Middleware is a general term for any programming that serves to glue together or mediate between two separate and usually already existing programs. It typically includes an application manager, a virtual machine, an interactive engine, libraries, and databases. In terms of interactive television, the middleware is often the software that provides services that occur between the server and end-user. This includes software that connects two separate applications together. This is particularly necessary as a number of different programs, platforms, and software are in use that are all oriented to the same goal of providing interactive television.

MIDI See musical instrument digital interface (MIDI).

miles of plant Miles of plant refers to the number of cable plant miles laid or strung by a cable system.

millions of instructions per second (MIPS) Millions of instructions per second—or MIPS—refers to a measure of the processor execution speed. It can be used as a measure of the power of a set-top box.

mini-slot A mini-slot is an integer multiple of 6.25-microsecond increments.

MIPS See millions of instructions per second (MIPS).

mixer A mixer is a non-linear circuit that produces an output at the sum and difference frequencies of an applied fixed or variable oscillator called the LO, and the FR input signal of interest.

MJPEG See motion-JPEG (MJPEG).

MMDS See Multi-Channel/Multi-Point Distribution (MMDS).

modem A modem is a data communications device. Modem is a combination of two words, modulate and demodulate. Strictly speaking, a modem is a device that accepts a digital signal, then converts or modulates it into an analog signal that another modem can convert back, or demodulate into digital form again. A modem’s speed and dependability are adversely affected by electromagnetic interference, or static. See also modulation.

modulation Modulation refers to the process when some characteristics of an electromagnetic wave are deliberately changed or manipulated for the purpose of transmitting information. Modulation is the process by which signals are transformed to represent information (or data). Modulation generally uses different frequencies to transmit data, such as frequency modulation (FM). See also frequency modulation (FM) and quadrature amplitude modulation (QAM).

modulator The modulator is the electronic equipment required to combine video and audio signals from a studio and convert them to radio frequencies (RF) for distribution on a cable system. Also, a modulator is a very low-powered television signal generator used to provide signals for distribution on a cable television system. See also radio frequency (RF).

mole technology Mole technology is an MPEG-2 concatenation technology. See also MPEG-2.

monaural Monaural refers to single channel audio. It is the opposite of stereo.

monitor plus Monitor plus refers to a spot monitoring service provided by Nielsen which records both  local broadcasts and national cable commercial activities.

monomode Monomode is when all photons take the same path down the center of the core of an optical fiber.

motion-JPEG (MJPEG) Motion-JPEG uses JPEG images as individual frames for motion, often at 30 frames per second. See also Joint Picture Experts Group (JPEG).

MP3 See MPEG Layer-3 Audio (MP3).

Moving Picture Experts Group (MPEG) The Moving Picture Experts Group is an international standards-setting group, working to develop standards for compressed full-motion video, still image, audio, and other associated information. MPEG is sufficient for all the major television standards, including National Television Systems Committee (NTSC) and high definition television (HDTV). See also National Television Systems Committee (NTSC), high definition television (HDTV), MPEG-1, and MPEG-2.

MPEG data stream An MPEG data stream is a multi-program data stream of interleaved and encoded data, video, and audio.

MPEG Layer-3 Audio (MP3) MP3 requires that downloaded files be sent to the user’s PC in their entirety before they can be played. Streaming, which starts playing before the download is finished, is the opposite of MP3.

MPEG program number An MPEG program number is the number associated with a specific program located within an MPEG-2 data stream. See also MPEG-2.

MPEG splicing MPEG splicing refers to the ability to cut into an MPEG bit stream for switching and editing.

MPEG transport stream ID TBD

MPEG-1 MPEG-1 is a standard for coding moving pictures and associated audio for digital storage media up to about 1.5 Mbps. MPEG-1 quality is comparable to VHS video. This standard is designed to work at 1.2 Mbps, which is the data rate of CD-ROMs, thus the video could be played from CDs. The quality, however, is not sufficient for television broadcast. MPEG-1 is usually used by interactive television content developers for television stills (pictures with no motion).

MPEG-2 MPEG-2 is an improved video compression standard over MPEG-1 that offers better resolution at the same 30 frames per second as MPEG-1. MPEG-2 supports field and frame-based coding, which is critical for 60 fields-per-second interlaced video formats. It also supports a range of resolutions and aspect ratios, and bilateral interpolation (that is, B-frames). MPEG-2 is commonly used by cable television operators and direct broadcast satellite providers to offer digital video services because of its efficient use of capacity, improved quality over analog, and stereo sound. See also frame and aspect ratio.

MPEG-4 MPEG-4 builds on MPEG-2 by allowing for greater use of multimedia/graphics within the video stream and for better compression. The MPEG-4 standards are for use in digital television, interactive graphics, and interactive multimedia—which includes video. MPEG-4 is expected to be a major standard in the interactive television realm. MPEG-4 delivers video quality as good as MPEG-2 at about one-third less the bit rate.
MSAP See media access control service access point (MSAP).

MSO See multiple systems operator (MSO).

MSTV See maximum service television (MSTV).

MTTR See mean time to repair (MTTR).

MTU See maximum transfer unit (MTU).

multicast A multicast is a message that a host sends out to multiple devices on the network. The terms multicast and narrowcast are often used interchangeably, although narrowcast usually refers to the business model, whereas multicast refers to the actual technology used to transmit the data. See also narrowcasting.

multicast backbone A multicast backbone is a network of hosts connected to the Internet and communicating via the Multicasting Internet Protocol (IP). It was an early broadband network set up to experiment with Webcasting and multicasting.

Multi-Channel/Multi-Point Distribution (MMDS) Multi-channel/multi-point distribution is a private service using a very high frequency (2 GHz) to transmit multiple television signals. This is also called wireless cable.

multimedia Multimedia refers to when different types of media are combined in a presentation such as video clips, text, and audio bites.

Multimedia and Hypermedia information coding Experts Group (MHEG-5) MHEG-5 is an ISO standard language that uses multimedia and hypermedia objects to build scenes within an interactive television application. MHEG-5 is intended to support the distribution of interactive multimedia/hypermedia applications in a client/server architecture across platforms of different types and brands. Approved by ISO in 1995, MHEG currently receives huge interest from many in the interactive television world. See also International Organization for Standardization (ISO).

multimedia cable network system (MCNS) The multimedia cable network system created the Data over Cable System Interface Specification (DOCSIS) standard for cable transmissions. See also Data Over Cable Service Interface Specifications (DOCSIS).

Multimedia Home Platform (MHP) The Multimedia Home Platform is an emerging standard platform for interactive television. It consists of an MHP viewer terminal, including all possible low-to-high functionality implementations, its associated peripherals, and the in-home digital network. MHP can support many content types, not just HTML and JavaScript. See also Hypertext Markup Language (HTML) and JavaScript.

multi-path Multi-path refers to copies of the desired signal that have arrived at th antenna after bouncing from objects between the signal source and the antenna. These signals can either cancel or reinforce each other.

multiple channel per carrier (MCPC) Multiple channel per carrier refers to a system that allows for multiple transmissions per single frequency channel.

multiple systems operator (MSO Multiple systems operator (MSO) refers to any company that operates multiple cable systems. Examples of MSOs are Time Warner Cable, Comcast, Cox, and others.

multiplexed analog components (MAC) Multiplexed analog components are an enhanced color television transmission system developed especially for satellite use.

multiplex Multiplex is a general term for combining types of data and/or signals and sending it to a receiver. In interactive television, the data is usually in then form of audio, video, and interactive data. Data streams can be multiplexed (combined) at the head-end, and demultiplexed by the receiver. See also head-end.

multiplexer A multiplexer is a device that allows several users to share a single circuit. It funnels different data streams into a single stream. At the other end of the communications link, another multiplexer reverses the process by splitting the data stream back into the original streams.

multiplexing Multiplexing is the potential transmission of several feeds of the same cable network with the same programming available at different times of the day. This is seen as one possible use of the additional channel capacity that may be made available by digital compression. Multiplexing is also used by some cable networks to mean transmitting several slightly different versions of the network, for example several MTV channels carrying different genres of music.

multipoint Network designers use the term multipoint to describe network links that end at a number of different points.

multipoint access Multipoint access refers to user access in which a single network termination supports more than one piece of terminal equipment.

multipoint connection A multipoint connection is a connection among more than two data network terminations.

multipoint videoconferencing Multipoint videoconferencing is when videoconferencing occurs between three or more locations or individuals.

musical instrument digital interface (MIDI) The musical instrument digital interface (MIDI) is a protocol that allows electronic devices, such as sound cards, to communicate with each other.
MIDI is most frequently associated with music being transported over the Internet.

must-carry Must-carry refers to the Federal Communications Commission (FCC) rule requiring cable systems to carry all local broadcast television signals in their market. See also Federal Communications Commission (FCC).

N + 1 N + 1 is a formula which refers to the Federal Communications Commission (FCC) requirements that provide for expansion of channel capacity for non-broadcast use. If the governmental, educational, public access, and leased channels are in use 80 percent of the weekdays—Monday through Friday—for 80 percent of the time during any three-hour period for six consecutive weeks, the system operator must expand the system’s channel capacity within six months. See also Federal Communications Commission (FCC).

NABTS See North American Basic Teletext Specification (NATBS).

narrowband Narrowband is a medium that can carry voice, fax, paging, and relatively slow-speed data (not full video applications), typically at 64Kbps or less. Narrowband can also mean a transmission medium or channel with a single voice channel. Vertical Blanking Interval (VBI) transmission is narrowband. See also vertical blanking interval (VBI).

narrowcast In terms of advertising and/or programming, narrowcast means to target the wishes and/or interests of smaller and smaller audiences, even down to the individual viewer. This is versus blanketing a region with a commercial and hoping enough interested viewers might see it even though most viewers would not be interested in the topic of the commercial.

narrowcasting Narrowcasting refers to the actual delivery of programming that addresses a specific need or highly focused audience.

NAT See network address translation (NAT).

National Cable and Telecommunications Association (NCTA) The National Cable and Telecommunications Association —formerly, the National Cable Television Association—is a trade association for the cable television industry. NCTA provides its members with a strong national presence by providing a single, unified voice on issues affecting the cable and telecommunications industry.

National Institute of Standards and Testing (NIST) The National Institute of Standards and Testing is a federal technology agency that works with the industry to develop and apply technology, measurements, and standards.

National Television Systems Committee (NTSC) The National Television Systems Committee (NTSC) is responsible for setting television and video standards in North America. The NTSC standard for television defines a video signal with a refresh rate of 60 half-frames (interlaced) per second. The format is 525 lines in a 4-MHz video bandwidth. All television sets sold in North America are compatible. The NTSC standard is incompatible with most computer video standards, which generally use RGB video signals. However, special video adapters are available for computers to convert NTSC signals into computer video signals and vice versa.

native application In OCAP, a native application is an application written in or compiled to the machine code for the particular processor. Typically, it is written in C C++, or assembly language and may be supplied with the OCAP implementation or downloaded over the cable. See also OpenCable™ Application Platform (OCAP).

navigator A navigator is a resident application, typically provided by the manufacturer, that the end user can activate at any time. Viewers can use the navigator to select services, applications, and initiate interoperable applications.

NCTA See National Cable and Telecommunications Association (NCTA).

NDIS See Network Driver Interface Specification (NDIS).

near-video-on-demand (NVOD) Near-video-on-demand is an entertainment and information service that broadcasts a common set of programs to customers on a scheduled basis. At least initially, NVOD services are expected to focus on delivery of movies and other video entertainment. NVOD typically features a schedule of popular movies and events offered on a staggered-start basis (every 15 to 30 minutes, for example). See also video-on-demand (VOD).

net weekly circulation (NWC) The net weekly circulation refers to the estimated number of television households viewing a particular station at least once per week, Monday-Sunday, 6 a.m. to 2 a.m., EST. The net weekly circulation is used to determine whether a station is significantly viewed in an area and must be carried by a cable system operating in that area.

NetBIOS Extended User Interface (NetBEUI) The NetBIOS Extended User Interface (NetBUI) is an enhanced version of NetBIOS. It is a network protocol used for communication between computers on a Local Area Network (LAN). See also local area network (LAN).

NetBEUI See NetBIOS Extended User Interface (NetBEUI).

network 1. A network is a group of radio or television outlets linked by cable or microwave that transmit identical programs simultaneously, or the company that produces programs for them. 2. A network is a collection of computers or other devices that communicate with one another over telecommunications networks. 3. A network is a collection of MPEG-2 transport stream multiplexes transmitted on a single delivery system—that is, all digital channels on a specific cable system.

network adapter A network adapter is typically a combination of hardware and software that enables a system to interact with others on a network such as the internet. Network adapters are big with video game players as it enables them to compete with others playing that game worldwide.

network address translation (NAT) Network address translation is a function, typically employed in internet connections, that performs address translation.

network address translation (NAT) gateway The network address translation (NAT) gateways operate much like a router, except messages they receive are addressed to them, not the actual destination of the message, a feature that allows a NAT gateway to connect an entire Local Area Network (LAN) to the Internet using a single Transmission Control Protocol/Internet Protocol (TCP/IP) address. When a NAT gateway receives a message from the internet, it examines the two-byte port number at the end of the To address, looks the port number up in a table, and does a NAT to point the message to the actual TCP/IP address for the destination of the message. To send a message from a computer on a LAN to a destination on the internet, NAT gateways reverse the process, except that it looks at the message’s From address, records the From address in its port number table, then replaces the From address with its own TCP/IP address and designated port number assignment. See also network address translation (NAT), local area network (LAN), and Transmission Control Protocol (TCP).

network attached storage Network attached storage is designed to separate storage resources from network and application servers. A network attached storage device attaches directly to an entity’s Local Area Network (LAN). A file system is located and managed on the network attached storage device and data is transferred to clients over industry-standard network protocols. See also application server and local area network (LAN).

network congestion Network congestion refers to a state of overload within a network, where there is a risk of traffic loss or service degradation.

Network Driver Interface Specification (NDIS) The Network Driver Interface Specification is Microsoft’s version of the software interface between the transport protocol and the data link protocol, which allows multiple protocol stacks to run over one network adapter.

Network Interface Card (NIC) A network interface card is a hardware interface card that connects a
computer to the network cabling. Each device on the network must have an operating system and software that enables it to have networking capacity. Some systems allow the wiring of the home to be used for transferring data on the network.

network layer The network layer refers to Layer 3 in the Open System Interconnection (OSI) architecture. It is the layer that provides services to establish a path between open systems. See also  Open Systems Interconnection (OSI).

network management Network management refers to the functions related to the management of data link layer and physical layer resources and their stations across the data network supported by the hybrid fiber/coax system. See also hybrid fiber coax (HFC) and data link layer.

network management system (NMS) The network management system is a system that provides fault and alarm management, configuration management, and equipment management.

Network Operations Center (NOC) The network operations center is a large group that is responsible for the day-to-day operations and maintenance of a network.

network operator A network operator is an organization, though generally a business, from which a network’s telecommunications are supervised, monitored, and maintained. This can include where cable and satellite signals are transmitted from. It does not necessarily include where the interactive television content was actually created, but it may if the organization is the content provider as well as the network operator.

network service provider In terms of interactive television, a network service provider is a network that among other services might offer interactive television to its customers, assuming that the customer has the right hardware for it.

network storage In terms of interactive television, network storage most often refers to when the content provider stores the content at their business’ location, and typically on their servers.

network termination Network termination is a part of the access network—owned by the carrier or the subscriber—located on the side of the subscriber’s home. The following are functions of the network termination: coupling of home wiring to the carrier wiring, grounding, radio frequency (RF) filtering, splitting, media conversion, remodulation, security and interdiction, provisioning, and loopback testing by the carrier. See also access network, radio frequency (RF), and subscriber.

network transport The network transport refers to the portions of a system that work towards transporting data over the network. This often is the most expensive part of broadband systems for the content provider. See also broadband and content provider.

NIC See Network Interface Card (NIC).

NIST See National Institute of Standards and Testing (NIST).

NMS See network management system (NMS).

NOC See Network Operations Center (NOC).

node 1. A node is an addressable unit in a network, which can be a computer, workstation, or some type of communications control unit. 2. A node is a point in a cable television system that interconnects traditional coaxial cable and fiber optics. The place where an optical signal is converted to a radio frequency (RF) signal, or vice versa. See also coaxial cable, fiber optics, and radio frequency (RF).

noise The word noise is a carryover from audio practice. Noise refers to random spurts of electrical energy or interference. Noise may produce a salt-and-pepper pattern over the picture. Heavy noise is sometimes called snow.

noise figure A noise figure is a measure of the ability of an amplifier to increase the strength of a signal while adding the minimum possible self-generated noise.

noncomposite Noncomposite video is a video signal without sync added to it.

nonlinear The term nonlinear is used for editing and storage of audio, video, and other data. Data can be brought up from anywhere on the media—such as a laser disc or computer disk—without having to know when, where, and how often it was entered in that media.

non-lossy compression Non-lossy compression refers to a compression technique that eliminates and/or reduces redundant data, thus keeping full picture quality but reducing the file size.

North American Basic Teletext Specification (NATBS) The North American Basic Teletext Specification is a joint EIA/CVCC Recommended Practice for Teletext: (NABTS) (ANSI/EIA-516-88) (May, 1988). This open standard is for the transmission of data over the Vertical Blanking Interval (VBI) of a television signal. See also vertical blanking interval (VBI) and Electronic Industries Association (EIA).

NTSC See National Television Systems Committee (NTSC).

NVOD See near-video-on-demand (NVOD).

NWC See net weekly circulation (NWC).

Nyquist frequency The Nyquist frequency is the lowest sampling frequency that can be used for analog-to-digital conversion of a signal without resulting in signal problems.

OCAP See OpenCable™ Application Platform (OCAP).

OEM See original equipment manufacturer (OEM).

off the air Off the air refers to the reception of a television signal that has been broadcast through the air.

Office of Telecommunications Policy (OTP) The Office of Telecommunications Policy is a division of the staff of the Executive Office of the President that advises the Executive Branch on communications policy, studies policy questions, and develops legislative proposals.

ohm The ohm is the standard unit of resistance, reactance, and impedance. A resistance of 1 ohm will conduct 1 ampere of current when a voltage of 1 volt is placed across it.

on-demand interface With an on-demand interface, the interface is literally the appearance of the information, data, images, etc. that you see on a computer screen or interactive television screen. This specific interface is oriented towards on-demand functions and most likely is an Electronic Program Guide (EPG) or Interactive Program Guide (IPG). See also electronic program guide (EPG) and interactive program guide (IPG).

on-demand interactivetelevision services On-demand interactive television services are related services offered over a network such as event previewing and ticketing, Video-on-Demand, shopping, gaming, and more. See also video-on-demand (VOD).

on-demand streaming On-demand streaming is streaming media that is transmitted to the user upon request.

one-to-one advertising One-to-one advertising is geared towards a more specific audience. Responses to the advertising can be measured, which can provide advertisers with a better understanding of what would sell and what would not. Interactive television can do this. Demographics about the viewer are procured—at times without their knowledge—and advertising geared towards their expected interests is delivered to them by the content provider. The viewer is less likely to skip or delete this type of advertising. These advertisements might also be in the form of extended infomercials, which are programs of substantial length that are actually commercials.

one-way system A one-way system can receive television programming through the broadband network. Customers wanting to order movies and other services must use traditional methods to do so rather than using the two-directional interactive capabilities offered through the two-way system. As the physical plant is upgraded, two-way systems will replace by one-way systems. See also two-way system.

OOB channel See out-of-band (OOB) channel.

open access Open access is a term used in regard to cable owner/operator’s desire to charge Internet Service Providers (ISPs) for using their cable equipment and networks for ISPs to provide their services to the ISPs customers. Customers get potentially much faster Internet connections but can in essence be double-billed, as they will also be using the cable company’s network. See also internet service provider (ISP).

Open Systems Interconnection (OSI) Open Systems Interconnect is a framework of the International Organization for Standardization (ISO) standards for communication between different systems made by different vendors, in which the communications process is organized into seven different categories that are placed in a layered sequence based on their relationship to the user.
Each layer uses the layer immediately below it and provides a service to the layer above. Layers 7 through 4 deal with end-to-end communication between the message source and destination, and layers 3 through 1 deal with network functions. See also International Organization for Standardization (ISO).

OpenCable™ OpenCable is an initiative led by CableLabs for its members, seeking to set a common set of requirements for interoperable digital set-top boxes, television receivers and other advanced digital devices manufactured by multiple vendors. These devices would be able to deliver digital video, data, and interactive services to a television set. See also Point-of-Deployment (POD) module and OpenCable™ Application Platform (OCAP).

OpenCable™ Application Platform (OCAP) The OpenCable Application Platform is a software interface specification that completely defines the OpenCable host software interface that executes OpenCable portable, interactive applications, and services. OCAP is a separate effort from the Advanced Television Enhancement Forum (ATVEF) content specification, but OCAP does call for support and extension of ATVEF as a part of the presentation engine (PE) requirements. See also Advanced Television Enhancement Forum (ATVEF) and presentation engine (PE).

OpenCable™ device An OpenCable device is an OpenCable-compliant digital set-top box or digital television receiver that allows the reception of existing cable television channels and provides the user interface for future, interactive applications.

OpenGL OpenGL is an open specification for an applications program interface for defining 2D and 3D objects. With OpenGL, an application can create the same effects in any operating system using any OpenGL-adhering graphics adapter. Its development was initiated by Silicon Graphics.

OpenTV OpenTV is a company providing middleware software for set-top boxes and back-end software to support set-top interactivity. They offer various generations of software for set-top boxes of varying capability. EN2 is the second generation version. OpenTV is a subsidiary of Liberty Broadband Interactive Television, Ltd.

operating system The operating system is the software that manages hardware and resources on a computer. Applications use the operating system to make requests for services and interact with the computer’s devices.

operation systems support (OSS) The operation systems support is the back office software used for configuration, performance, fault, accounting, and security management.

optical fiber An optical fiber is an extremely thin, flexible thread of pure glass, able to carry one thousand times the information possible with traditional copper wire.

optical overload Optical overload is a condition of high input current that causes pulse width distortion at the output of the TIA.

optical resolution The optical resolution is the resolution at which a device can show the viewer an image. The term is most frequently used concerning scanners and digital cameras.

original equipment manufacturer (OEM) An original equipment manufacturer is when one company manufactures a brand for another company. An example would be when one brand and/or model of VCR is manufactured at the VCR plant(s) of another brand of VCR.

organizationally unique identifier (OUI) An organizationally unique identifier is a 3-octet Institute of Electrical and  Electronic Engineers (IEEE) assigned identifier which can be used to generate universal local area network (LAN) media access control (MAC) addresses and Protocol Identifiers per ANSI/IEEE Std. 802 for use in local and metropolitan area network applications. See also Institute of Electrical and Electronic Engineers (IEEE), local area network (LAN), and media access control (MAC).

OSI See Open Systems Interconnection (OSI).

OSS See operation systems support (OSS).

OTP See Office of Telecommunications Policy (OTP).

OUI See organizationally unique identifier (OUI).

out-of-band (OOB) channel An out-of-band channel is the combination of the forward and reverse out-of-band communications channels. The OOB channel provides an IP-based communication channel between the network and the digital set-top box.

overbuilder An overbuilder is a company that overbuilds an incumbent telecommunications operator and offers customers a competitive alternative, generally with highly advanced fiber-optic networks.

overlapping markets Overlapping markets refer to the situation where a television station’s predicted Grade B contour is overlapped by the predicted Grade B contour of a television station located in a different market. See also predicted Grade B contour.

overscanned Overscanned refers to a television picture that gets too big for the television screen. This causes the edges of the picture to be cut off and hidden.

P frames P frames are one of three types of frames used in the compressed (coded) MPEG-2 signal. See also MPEG-2.

package A package is the transmission unit used to distribute content. It contains one or more assets, and their associated metadata. It is transmitted over the distribution interface. A package is the means by which a version of a product is distributed. A package may contain all assets for a version of a product, or it may contain a subset of the assets in the case of an update. In general, a package consists of a group of assets. See also asset and metadata.

packet A packet is a series of bits containing data and control information, including source and destination node addresses, formatted for transmission from one node to another. A packet contains a header consisting of control information such as the sender, receiver, and error-control data and the message itself. A packet may be fixed or variable in length.

packet identifier (PID) A packet identifier is a unique integer value used to identify elementary streams of a program in a single- or multi-program MPEG-2 stream. See also MPEG-2.

packet loop A packet loop is a digital loop on which all information—signaling and user content—is encoded in packets.

packet-switched network (PSN)
A packet-switched network transports information by breaking up the bit stream into addressable digital packets that are transmitted independently and then reassembled in the correct sequence at the destination. Because these networks allow sharing of communications links, they are more efficient than circuit-switched networks.

packet switching Packet switching refers to how data is configured when being transmitted
through the Internet. Data is broken into chunks with an address to where it is going. Each of these chunks of data is directed by routers, gateways, and servers, through many different routes to their destination.

page In terms of interactive television, a page refers to what is on the television screen at any given moment.

pairing Pairing refers to the partial or complete failure of interlace in which the scanning lines of alternate fields do not fall exactly between one another but tend to fall (in pairs) one on top of the other.

PAL See Phase Alternating Lines (PAL).

palette In terms of computer graphics, the palette is the set of available colors. For a given application, the palette may only be a portion of the total number of colors that your computer can actually display. A palette is also known as a Color Look-Up Table, or CLUT. See also Color Look-Up Table (CLUT).

pan and scan Pan and scan is the most common technique used to fit programming made with a 16:9 aspect ratio (such as movies) into the 4:3 aspect ratio of a standard analog television receiver. Pan and scan works by matching the height of the movie image to the height of the television screen. If the movie image is then centered on the television screen, the edges of the movie image will not be seen. Pan and scan is an alternative to showing the program in letterbox format. See also aspect ratio and letterbox.

parallel data Parallel data refers to the transmission of data bits in groups along a collection of wires, which is called a bus. See also bus.

parental control With parental control, the subscriber may have an optional content controlling abilities which is provided by the subscriber’s content provider—either a satellite or cable company.

parity Parity is a method of verifying the accuracy of transmitted and recorded data. An extra bit (0 or 1) is added to the data transmission—which is already in the form of 0s and 1s—and the receiving computer(s) involved in the transmission, check to make sure the data transmission (the bits) have that one extra bit. If the transmission does not have the extra bit, then that indicates that there could have been a faulty transmission. Parity may be even or odd.

parsing In the computer world, parsing generally means dividing and/or translating the source code of a program or application into segments so it can be better understood by the computer.

passive In terms of interactive television, passive generally refers to television viewing without the interactive television functions.

passive component A passive component requires no external source of power for it to function.

passive device A passive device is a circuit or network not using active devices such as tubes or transistors.

passive entertainment In terms of interactive television, passive entertainment refers to the attitude that television viewers prefer to primarily receive data from their televisions and not interact with it.

pay cable Pay cable is cable programming services for which subscribers pay an additional fee above the basic cable service charge. This is also called premium cable. See also premium cable.

pay cable unit A pay cable unit refers to the premium service to which a household subscribes. Each premium service is counted as one unit.

Pay-Per-View (PPV) Pay-Per-View refers to television programming for which cable subscribers pay a separate fee for each program viewed.

pay programming Pay programming is movies, sports, and made-for-cable specials that are available to the cable customer for a charge in addition to the basic fee.

PCI See peripheral component interface (PCI).

PCM See pulse code modulation (PCM).

PCR See program clock reference (PCR).

PCS See personal communications service (PCS).

peak white Peak white is a term used loosely to mean reference white.

peer entities Peer entities are entities within the same layer.

peer-to-peer network A peer-to-peer network is a wireless or wired computer network that has no server or central hub or router. All the networked PCs are equally able to act as a network server or client, and each client computer can talk to all the other wireless computers without having to go through an access point or hub. However, because there is no central base station to monitor traffic or provide Internet access, the various signals can collide with each other, reducing overall performance.

penetration Penetration is the ratio of the number of cable customers to the total number of households passed by the system.

per hop behavior (PHB) In the Internet Engineernig Task Force (IETF) Differentiated Services (DiffServ) approach to quality of service differentiation, the treatment by a network router or switch of a group of network traffic flows for the hop to the next router switch is referred to as the per hop behavior (PHB). Packets marked or tagged with a common service classification in the packet header are aggregated into flow bundles that are treated the same, for example, have the same priority or the same risk of being discarded in the event of network congestion. See also internet engineering task force (IETF) and packet.

percentage sync Percentage sync is the ratio, expressed as a percentage, of the amplitude of the synchronizing signal to the peak-to-peak amplitude of the picture signal between blanking and  reference white level.

performance standards Performance standards refer to the minimum technical criteria that must be met by cable television systems, consistent with the standard set by the Federal Communications Commission (FCC) or the local ordinance. See also Federal Communications Commission (FCC).

per-inquiry advertising Per-inquiry advertising is the direct response advertising for which the cable network or system running the commercial is paid based on the number of responses received rather than the air time used.

peripheral A peripheral is a device connected to anything that is not part of the original equipment. In terms of interactive television, a peripheral could be an item connected to the set-top box and controlled by the set-top box’s microprocessor.

peripheral component interface (PCI) The peripheral component interface is an interface standard for connecting hardware expansion cards to a computer. The typical PCI connection is a slot, or edge-card connector, on the computer’s motherboard allowing devices such as network cards, graphics cards, or drive controllers to be connected to the computer. Some PCI devices are integrated onto the motherboard, especially in the case of brand-name computers. PCI has eclipsed ISA as the interface of choice due to its higher transfer rate, ease of configuration, and improved plug-and-playability. See also industry standard architecture (ISA) and plug-and-play.

permanent virtual circuit (PVC) A permanent virtual circuit is a point-to-point connection between two specific locations on an ATM, Frame Relay, or X.25 network. PVCs are pre-defined by the ATM, Frame Relay, or X.25 network administrator. See also switched virtual circuit (SVC) and asynchronous transfer mode (ATM).

personal communicationsservice (PCS) A personal communications service is a digital network deployed in cellular. It refers to any service offered using the personal communications network, such as paging, voice mail, and voice telephone.

personal video recorder (PVR) A personal video recorder is the hardware used by the consumer that is used both to digitally record and play back programming. You receive television like you normally do. The content provider—whether television networks, cable, satellite, etc.—sends the content—television shows, news, etc.—and you plug it into the set-top box. See also content provider.

personalized advertising In interactive television, personalized advertising is advertising geared towards a specific audience. Responses to the advertising can be measured, which can provide advertisers with a better understanding of what would sell and what would not. Interactive television can facilitate this. Demographics about the viewer are procured—at times without their knowledge— and advertising geared towards their expected interests are delivered to them by their content provider. The viewer is less likely to skip or delete this type of advertising. These advertisements might also be in the form of extended infomercials, which are programs of substantial length that are actually commercials. See also content provider and infomercial.

personalized content In terms of interactive television, personalized content refers to content that could be standard programming or advertising, which is produced and presented to an audience that the content provider thinks would have more interest in it than the general masses. The content may be information the end-user has asked for or is data that is in the same general category of what a group of end-users have previously shown a pronounced interest in. See also content provider.

phase A phase is a relative quantity describing the time relationship between or among waves having identical frequency. The complete wave cycle is divided into 360 equal parts, called degrees of phase.

Phase Alternating Lines (PAL) Phase Alternating Lines (PAL) is a video signal standard. It is the analog television format used in most of Western Europe. It is used in other major areas such as China, India, Australia, Western Europe, and South America. Its analog television counterpart used in America is National Television Systems Committee (NTSC). PAL uses 625 lines (575 lines are visible) and has a 50 Hz frame refresh rate. See also National Television Systems Committee (NTSC).

phase distortion When the output of an amplifier fluctuates in phase, even though the input does not, the circuit introduces phase distortion into the signal.

phase jitter Phase jitters are variations arising in a channel and caused by incidental frequency modulation of signals transmitted over the channel. This occurs when the carrier supplies frequencies in a frequency-division-multiplexed carrier system that are not perfectly constant. See also frequency division multiplexed (FDM).

phase modulation Phase modulation is when the information is impressed on a radio frequency signal by varying its phase angle. See also radio frequency (RF).

phased array A phased array is a type of antenna design that incorporates two or more elements that integrate signal information received from the spatially separate elements, and that transmit in a coordinated manner—either simultaneously or alternately.

PHB See per hop behavior (PHB).

photodiode A photodiode is a semiconductor device that converts light to electrical current.

photoresistor A photoresistor is a device that exhibits a variable resistance, depending on the amount of light that strikes it.

physical (PHY) layer Layer 1 in the Open System Interconnection (OSI) architecture is the physical layer. The physical layer provides services to transmit bits or groups of bits over a transmission link between open systems and which entails electrical, mechanical, and handshaking procedures. See also Open Systems Interconnection (OSI).

physical media department (PMD) sublayer The physical media department sublayer is a sublayer of the physical layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical, and handshaking procedures.

pica A pica is a measure of a line’s width. One pica equals one-sixteenth of an inch.

picture element A picture element is one of many monochrome or color dots that make up a television picture.

picture manipulators A picture manipulator is the actual function of a device such as a video camera that creates an effect on the video image such as freezing the image for viewing as a still image—even if temporarily—or making the image display in slow motion. It is that part of the video camera machinery that produces the still and slow motion that are considered picture manipulators.

picture tube A picture tube is a cathode-ray tube used to produce an image by variation of the intensity of a scanning beam.

pillarbox A pillarbox describes a frame in which the image fails to fill horizontally.

pixel A pixel is the smallest element of a display surface that can be independently assigned color or intensity. Each pixel is composed of three phosphors: one green, one red, and one blue. Digital televisions have different size pixels than analog televisions.

Plain Old Telephone Service (POTS) The phrase Plain Old Telephone Service often is used to refer to analog voice telephone services provided over the public switched telephone network.

plastic optical fiber (PoF) Plastic optical fiber is a plastic cable used—for short distances only—as an alternative to fiber optic cable. Although plastic is not as transparent as glass, it is more malleable and less expensive. PoF is a possible choice for indoor networking.

plug-and-play Plug-and-play refers to an Intel-developed hardware standard created to automate the setup and configuration of hardware devices connected to a computer. In theory, it allows you to plug a device into the computer and play it without going through a complicated setup process.

plug-in A plug-in refers to a set of functionality which can be added to a generic platform in order to provide interpretation of DVB registered, but non-DVB-J, application formats. For example, HTML3.2 or MHEG-5 are examples of plug-ins. See also MHEG-5.

PMD See physical media department (PMD) sublayer.

POD See Point-of-Deployment (POD) module.

PoF See plastic optical fiber (PoF).

point A point is a measure of the number, character, or letter’s height on your television or computer screen. One inch equals 72 points.

Point-of-Deployment (POD)moduleA Point-of-Deployment (POD) module is a removable security module—in a PCMCIA or PC card form factor—which, when inserted in an OpenCable certified set-top box, television, or other device, enables delivery of digital video programming and other services. The OpenCable specification is designed in part to support the retail sale of advanced digital set-top boxes and other devices. Cable operators will provide PODs directly to customers who request them. See also OpenCable™.

point-of-presence (POP) Point-of-presence refers to the point where the inter-exchange carrier’s responsibilities for the line begin and the local exchange carrier’s responsibility ends. Point-of-presence also refers to the location of a communications carrier’s switching or terminal equipment.

point-to-point Point-to-point refers to the circuit connecting two nodes only, or a configuration requiring a separate physical connection between each pair of nodes.

Point-to-Point Protocol (PPP) The Point-to-Point Protocol is a method of transmitting Transmission Control Protocl/Internet Protocol (TCP/IP) and other networking protocols over a dial-up or Wide Area Network (WAN) connection. See also Transmission Control Protocol/Internet Protocol (TCP/IP) and Wide Area Network (WAN).

pole attachment When cable television systems use existing pole lines maintained by utilities, an attachment contract must be negotiated between the parties of interest. This is referred to as the pole attachment.

POP See point-of-presence (POP) and Post Office Protocol 3 (POP3).

port The port is a physical connector on a device enabling the connection to be made.

Post Office Protocol 3 (POP3) Post Office Protocol 3 is the current version of the most common protocol for receiving email on a Transmission Control Protocol/Internet Protocol (TCP/IP) network. See also Transmission Control Protocol/Internet Protocol (TCP/IP).

POTS See Plain Old Telephone Service (POTS).

power amplifier A power amplifier delivers a certain amount of alternating-current power to a load. A power amplifier is used in audio frequency and radio frequency applications.

power cycle Power cycle refers to the act of turning the electrical power to a device off and then back on. A power cycle is often used to reset the device.

power gain Power gain is an increase in signal power between one point and another. It is used as a specification for power amplifiers.

power transistor A power transistor is a semiconductor transistor designed for power-amplifier applications at audio and radio frequencies.

PowerTV PowerTV’s offerings include an operating system specifically designed and implemented for the digital interactive cable broadband network, middleware functionality supporting HTTP protocol, HTML content creation, and PersonalJava development. The PowerTV Operating
System is currently deployed in over 2.5 million customer homes. PowerTV’s operating system, middleware layer, and applications are most prominent in the Scientific-Atlanta networks, deployed on the Scientific-Atlanta Explorer 2000 and 3000 series, Pioneer Voyager I series set-top boxes, and PACE set-top boxes. See also Explorer, Hypertext Transfer Protocol (HTTP), and Hypertext Markup Language (HTML).

PPP See Point-to-Point Protocol (PPP).

PPV See Pay-Per-View (PPV).

predicted Grade A contour A predicted Grade A contour is the line representing the service area in which a good picture is computed to be available 90 percent of the time at 70 percent of the receiver locations. Signal contours determine what educational channels are carried on a cable system and, in similar markets, what stations must be carried from other small markets.

predicted Grade B contour A predicted Grade B contour is the concentric area marking a television
station’s service area in which a good analog picture is computed to be available 90 percent of the time at 50 percent of the receiver locations.

premium cable Premium cable is cable programming services for which subscribers pay an additional fee above the basic cable service charge. It is also called pay cable. See also pay cable.

presence awareness Presence awareness is the ability to know a person’s availability and status across all communication channels, and importantly to know this while they are online. While this aids in marketing, many consider it an invasion of privacy.

presentation engine (PE) In OCAP, the presentation engine is responsible for the appearance of information on the user interface (the display), and enables content to be displayed on a variety of devices. The presentation engine incorporates native code that decodes text (HTML, ECMAScript) into meaningful operations, and uses web-based software from the computer world, the web browser. However, the presentation engine has only limited ability to perform complex logic and arithmetic operations and lacks the security of the execution engine, which is why the execution engine is also required by OCAP. See also Hypertext Markup Language (HTML), ECMAScript, execution engine, and OpenCable™ Application Platform (OCAP).

Presentation Time-Stamp (PTS) The presentation timestamp is a field that may be present in a Packetized Elementary Stream (PES) packet header that indicates the time that a presentation unit is presented in the system target decoder.

processing gain Processing gain is a function of spread spectrum carrier sense multiple access (CDMA) technology used in digital cellular. Processing gain is a measure of the robustness of the system. It recovers the processed low power signal used to eliminate noise.

profile A profile is a record stored on a computer or other device containing the settings and preferences for each of the users sharing that computer.

program In interactive television, a program is a discrete broadcast or on-demand show or event.

program clock reference (PCR) The program clock reference is the time stamp in the transport stream from which MPEG decoder timing is derived. See also Moving Picture Experts Group (MPEG).

program non-duplication Under Federal Communications Commission (FCC) rules, a cable system must black-out the programming of a distant television station it carries, when the system would duplicate a local station’s programming, on the request of the local station. This is referred to as program non-duplication. See also Federal Communications Commission (FCC).

program stream In MPEG-2, a program stream is a multiplex of variable-length digital video and audio packets from one or more program sources having a common time-base. See also MPEG-2

Program-Specific Information (PSI)
In MPEG-2, program-specific information is normative data necessary for the demultiplexing of transport streams and the successful regeneration of programs. See also MPEG-2.

progressive scanning Progressive scanning is a system of scanning in which adjacent lines of a picture are scanned in succession—that is, scanned in order from top to bottom, such as 1, 2, 3, 4, 5, 6... This means the image is displayed in one pass instead of two, as is done with interlaced scanning.

propagation Propagation refers to the non real time transfer of content between servers within an AMR over a propagation network.

protocol A protocol is the set of rules or standards that enables communication between computers on a network, in its simplest form, a protocol is the language used by two computers to transfer information.

proxy server A proxy server is a network component between a local area network (LAN) and the internet providing security, administrative control, and data caching. It is also a firewall that protects the network from intrusion. See also local area network (LAN).

PSI See Program-Specific Information (PSI).

PSN See packet-switched network (PSN).

PTS See Presentation Time-Stamp (PTS).

public access Public access refers to a non-commercial channel set aside by a cable system for use by the public, on a first come first serve, non-discriminatory basis.

public television Public television is the name given to noncommercial television broadcasting.

pull mode Pull mode is a delivery method in which a subscriber demands and receives data from the provider. See also push mode.

pulse code modulation (PCM) Pulse code modulation is the internationally accepted Codex used by telephone companies to translate between the 56 and 64Kbps digital signaling technologies and the analog signals sent across Plain Old Telephone Service (POTS) telephone lines. PCM codes are seven or eight bits in size, which means each code byte has 128 or 256 possible values. North American POTS connections generally only use 7 bit codes. See also Plain Old Telephone Service (POTS).

push mode Push mode is a delivery method where the service provider transmits data on a fixed, predictable schedule, or in response to an event such as the updating of data in the subscriber’s database. See also pull mode.

PVC See permanent virtual circuit (PVC).

PVR See personal video recorder (PVR).

QAM See quadrature amplitude modulation (QAM).

QoS See quality-of-service (QoS).

QPSK See quadrature phase-shift keying (QPSK).

quadrature amplitude modulation (QAM) Quadrature amplitude modulation (QAM) is a method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. QAM is a modulation scheme used by telecommunications providers. More advanced modulation offers increased capacity—for example, 256 QAM offers greater capacity/transmission speeds than 64 QAM. See also modulation, radio frequency (RF), and amplitude.

quadrature phase-shift keying (QPSK) Quadrature phase-shift keying is a method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits. It is used for transmitting digital signals over an analog medium. See also modulation and radio frequency (RF).

quality-of-service (QoS) Quality of Service guarantees network bandwidth and availability for applications. Any real time media stream that crosses a DOCSIS access link needs to be given prioritized traffic management treatment in order to assure the best user-perceived quality end-to-end. DOCSIS 1.1 provides several potential methods for classifying traffic—ranging from DIFFSERV to flow-classification—and several access-link traffic management functions, which can be applied to such classified traffic (priority, CBR real-time polling, header compression, and stream-specific modulation methods). See also DOCSIS.

radio button A radio button offers two or more options and lets you choose only one of the available options. A radio button is different from a check box as a check box can accept multiple checked items for one question.

radio frequency (RF) Radio frequency refers to the analog electrical signals sent over the cable. Conventional (broadcast) television and radio, as well as cable television, deliver RF signals to your television and radio. RF is quickly becoming yesterday’s news to many cable television providers who are installing fiber-optic lines that will replace today’s cables. See also fiber optics.

radio frequency (RF) interference Radio frequency interference refers to the undesired signals received by a user. Frequently, RF interference refers to those signals that miss their desired user become interference energy to users in the same or adjacent cells.

ranging Ranging is the process by which a cable modem learns its distance from the head-end. Ranging is a continual process, due to the expansion and contraction of cable that occurs during the day. See also cable modem and head-end.

raster A raster is the scanned—illuminated—area of the cathode ray picture tube.

rate conversion Rate conversion is the process of converting from one digital sample rate to another. The digital sample rate for the component digital video format is 13.5 MHz. For the composite digital video format, it is either 14.3 MHz for National Television Systems Committee (NTSC) or 17.7 MHz for Phase Alternating Lines (PAL). See also National Television Systems Committee (NTSC) and Phase Alternating Lines (PAL).

RDC See reverse data channel (RDC).

Real-time Protocol/Real-time Control Protocol (RTP/RTCP) The Real-time Protocol/Real-time Control Protocol is the Internet Engineering Task Force (IETF) specification for audio and video signal management. It allows applications to synchronize and spoil audio and video information. See also internet engineering task force (IETF) and refer to www.ietf.org.

reboot Reboot is the act of reloading the operating system of a computer, usually by resetting the power to the computer with the power switch.

rebuild Rebuild refers to the physical upgrade of a cable system, often involving the replacement of amplifiers, power supplies, passive devices, and sometimes the cable, strand, hardware, and subscriber unit.

receiver isolation Receiver isolation is the attenuation between any two receivers connected to the system. See also attenuation.

receiver A receiver is an electronic device which can convert electromagnetic waves into either visual or aural signals, or both. For cable television, usually the subscriber’s television set.

record keeping server In a PacketCable network, the record keeping server accepts partial billing information generated by a distributed set of PacketCable elements and correlates this information into a single, coherent record that describes the resources used during the service.

redundant Redundant refers to the processing and/or transmitting organizing data in a manner that minimizes duplication. In terms of data transmission, the aim is to make it so it does not stop at the same point twice, which can make for inefficiency and slowing down of the transmission.

reference platform A reference platform is the basic underlying architecture—hardware and middleware and software when applicable. Original equipment manufacturer (OEM) businesses can add to the reference platform proprietary software and other enhancements to make the product identifiable as theirs and function to their specifications. See also original equipment manufacturer (OEM)

reflections or echoes In video transmission, reflections or echoes may refer either to a signal or to the picture produced. In a signal it, the reflection is either waves reflected from structures or other objects or waves which are the result of impedance or other irregularities in the transmission medium. In a picture, echoes are observed in the picture produced by the reflected waves. See also echo.

remote Remote refers to the television or set-top box’ mechanism that makes it respond to the remote control.

remote bridge A remote bridge connects physically dissimilar network segments across Wide Area Network (WAN) links. See also Wide Area Network (WAN).

remote procedure call (RPC) A remote procedure call provides the ability for client software to invoke a function or procedure call on a remote server machine

rendering Rendering is when a graphics program creates the image you have specified.

repeater A repeater is a network device that repeats signals from one cable onto one or more other cables, while restoring signal timing and waveforms.

ReplayTV ReplayTV is one of two major over-the-air personal video recorders (PVRs); the other one is TiVo. Both of these products—ReplayTV and TiVo—require a telephone line to enable value-added services such as program guides. Some cable television set-top boxes now include PVR functions. See also personal video recorder (PVR) and TiVo.

reprovision Reprovision is the term given to the process of resetting a cable modem by removing its entry from the cable router, then adding it back on to re-establish the connection. See also cable modem.

repurposing Repurposing refers to using content intended for one medium for another medium. For example, using content developed for print media for interactive television.

request for comments (RFC) A request for comments is a technical policy document of the Internet
Engineering Task Force (IETF). See also internet engineering task force (IETF).

resident application A resident application is an application or program that is built into the memory of the set-top box. These are updated, often automatically, by the service provider via the data stream (signal) that the set-top box receives from the service provider.

resident program guide The resident program guide is the program guide, most likely an electronic
program guide (EPG) or an interactive program guide (IPG), that the interactive system offers the viewer. It could be based in the set-top box or at the server. See also electronic program guide (EPG) and interactive program guide (IPG).

residential gateway A residential gateway is a part of the access network which adds network
functionality and multiplexes different services. The gateway must perform the basic functions of media translation and address translation. See also gateway, access network, and multiplex.

resistance Resistance is the opposition that a substance offers to the flow of electric current.

resistor A resistor is an electronic component that is deliberately designed to have a specific amount of resistance.

resolution 1. Resolution refers to the amount of resolvable detail in the horizontal direction in a picture. It is usually expressed as the number of distinc vertical lines, alternately black and white that can be seen in three-quarters of the width of the picture. This information usually is derived by observation of the vertical wedge of a test pattern. A picture that is sharp and clear and shows small details has good, or high, resolution. If the picture is soft and blurred and small details are indistinct it has poor, or low, resolution. Horizontal resolution depends upon the high-frequency amplitude and phase response of the pickup equipment, the transmission medium, and the picture monitor, as well as the size of the scanning spots. 2. Resolution also refers to a measure of picture resolving capabilities of a television system determined primarily by bandwidth, scan rates and aspect ratio. Resolution relates to fineness and details perceived.

resource A resource is either hardware or software that is available for an application to use. The following resources are non-sharable but can be used by your application: tuners, MPEG decoders, keyboards, and video display.

resource descriptor A resource descriptor uniquely defines a resource.

resource server A resource server manages a resource and sets policies for sharing that resource. A resource client is an application that uses a resource.

response time The response time is the length of time between the occurrence of an event and the response of an instrument or circuit to that event.

return loss The return loss is the parameter describing the attenuation of a guided wave signal—for example, via a coaxial cable—returned to a source by a device or medium resulting from reflections of the signal generated by the source. See also coaxial cable.

return on investment (ROI) The return on investment is the amount spent on an interactive television marketing campaign compared to the amount earned as a result of the interactive television campaign. For example, if the marketing campaign costs $5,000, and the campaign generates $10,000 in profit, then the ROI for the campaign is $5,000, or 50%.

return path The return path describes traffic and paths that go from the subscriber to the head-end. Return path is also known as upstream, or reverse path.

reuse/frequency reuse Reuse/frequency reuse refers to the use of frequency (channels) more
than once in a wireless network. It is equated primarily with the basic cellular grid design, where each cell uses each channel once within its boundaries and is insulated from other cells using that frequency to allow for anticipated interference. Due to the shortcomings of conventional
transmission techniques, frequency reuse in adjacent cells has been largely implausible until the recent development of spatial processing technology, which can enable same-cell frequency reuse.

revenue generating unit (RGU) The revenue generating unit refers to one additional cable subscription unit. For example, a customer who signs up for digital video and high-speed Internet access is counted as two revenue generating units, because the customer is signing up for two subscriptions.

reverse channel Reverse channel is the direction of signal flow toward the head-end, away
from the subscriber. It is equivalent to upstream.

reverse data channel (RDC) A reverse data channel is a data channel carried from the set-top box to the head-end in a modulated channel at a typical rate of 1.5 to 3 Mbps. See also head-end

reverse path forwarding Reverse path forwarding is a technique where a router receives a packet, then floods the packet out on all paths, except the path on which it received the packet.

R-F pattern An R-F pattern is sometimes applied to describe a fine herringbone pattern in a picture. An R-F pattern may also cause a slight horizontal displacement of scanning lines resulting in a rough or ragged vertical edge of the picture. An R-F pattern is caused by high-frequency interference.

RF See radio frequency (RF).

RFC See request for comments (RFC).

RGB RGB is a video image that requires three separate signals from a computer, one for each color—red, blue, and green.

RGU See revenue generating unit (RGU).

rich media Rich media refers to presenting a combination of audio, video, text, and graphics to create an interactive and enhanced media experience. Rich media can denote the use—or offering—of additional information related, and complementing the viewed programming/presentation.

ring A ring is a network topology in which the nodes are connected in a closed loop. Data is transmitted from node to node around the loop, always in the same direction.

ringing Ringing is an oscillatory transient occurring in the output of a system as a result of a sudden change in input. Ringing results in close-spaced multiple reflections, particularly noticeable when observing test patterns, equivalent square waves, sine-squared signal, or any fixed objects whose
reproduction requires frequency components approximating the cutoff frequency of the system.

RIP Routing Information Protocol (RIP).

RJ-11 jack/connector An RJ-11 connector is the small, modular plug used for most analog telephones. It has six-pin slots in the head, but usually only two or four of the pins are used.

RJ-45 jack/connector An RJ-45 connector is similar in appearance to a modular RJ-11 connector, but is wider and has eight-pin slot positions instead of six. RJ-45 connectors are used to connect ISDN S/T Interfaces and for 10-Base-T Ethernet cabling.

roadblocking Roadblocking refers to the practice of stripping commercials in designated time periods across multiple cable channels. Roadblocking can be an effective method for catching channel surfers.

roll-off A roll-off is the gradual attenuation of gain-frequency response at either or both ends of the transmission pass band. See also attenuation and gain.

router Routers are special network devices used to connect one recognized computer network to another. Routers work like a post office; they examine the To addresses of network messages they are given and use part of the address like a zip code to figure out which computer network to send it to. Once a router has figured out which network the message should go to, it sends the message to another router, which repeats the process until the last router in the chain sends it directly to the computer listed in the destination address. Most wide area networks (WANs) use routers to connect one local area network (LAN) location to another. See also local area network (LAN) and Wide Area Network (WAN).

Routing Information Protocol (RIP) A protocol of the Internet Engineering Task Force (IETF) for exchanging routing information about Internet Protocol (IP) networks and subnets. See also internet engineering task force (IETF) and Internet Protocol (IP).

RPC See remote procedure call (RPC).

RTP/RTCP See Real-time Protocol/Real-time Control Protocol (RTP/RTCP).

safe viewing area The safe viewing area is the physical area of the screen that you can count on being filled with the image.

sample In analog to digital signal processing, a sample is taken at regular intervals to establish the electrical potential (voltage) present in an analog system at a given point in time. Each sample is then assigned a digital value.

sample rate In analog to digital signal processing, the sample rate is the interval at which samples of an analog signal are taken.

SAP See second audio program (SAP) and service access point (SAP).

satellite A satellite is a device located in geostationary orbit above the earth which receives transmissions from separate points and retransmits them to cable systems, Direct Broadcast Satellite (DBS), and others over a wide area.

satellite dish antenna A satellite dish antenna is a system for concentrating the weak signals sent from a satellite.

satellite downlink A satellite downlink is a data service that broadcasts data from an orbital
satellite to terrestrial receivers. Satellite downlink is used by some satellite television vendors to provide a high-speed feed for receiving data from the Internet. Data sent to the Internet—web page requests, outbound email, etc.—must be sent by more conventional means, such as a dial-up modem connections to a local Internet Service Provider (ISP). See also internet service provider (ISP).

Satellite Master Antenna Television System (SMATV) Satellite Master Antenna Television System are systems that serve a concentration of television sets such as an apartment building, hotel, etc., using one central antenna to pick up broadcast and/or satellite signals. See also antenna and satellite.

satellite provider A satellite provider is the business that provides and probably maintains the
actual hardware and equipment, including the satellites, to make the actual transmission to the viewer possible. The satellite provider does not necessarily provide the receivers that are used by the end-user.

satellite relay distribution (SRD) Satellite relay distribution redistributes television signals to distant markets via satellite.

satellite receiver The satellite receiver is the tuner portion of your satellite entertainment system. It is the part that takes commands from your remote control.

saturation Saturation is an attribute of perceived color or the percentage of hue in a color. Saturated colors are called vivid, strong, or deep. De-saturated colors are called dull, weak, or washed out.

scalable Scalable refers to the ability to pattern, make, set, regulate, or estimate according to some rate or standard.

scalable video Scalable video refers to video compression that can handle a range of bandwidths. In scalable video, a video stream is decomposed to a base stream and one or more additional streams. The additional streams are to be combined with the base stream to produce higher quality video.

scanning Scanning is the technique of building up a television image, in a CRT receiver, as a series of horizontal lines. The beams from the electron guns at the rear of the picture tube scan the image from right to left and top to bottom. The number of lines is a measure of the resolution. A standard
analog television picture uses interlaced scanning, where each complete picture is displayed as two frames: the first frame having the odd-numbered lines and the second having the even-numbered lines. Each screen phosphor emits light for a short time after being struck by the moving electron beam. This, together with persistence of human vision, gives the appearance of a flicker-free, complete continuous image.

scanning line A scanning line is a single continuous narrow strip of the picture area containing highlights, shadows, and halftones, determined by the process of scanning.

SCP See service control point (SCP).

SCR See system clock reference (SCR).

scramble Scramble refers to a signal security technique for rendering a television picture unviewable, while permitting full restoration with a properly authorized decoder or descrambler.

SDK See software development kit (SDK).

SDMA See spatial division multiple access (SDMA).

SDTV See standard definition television (SDTV).

SDU See service data unit (SDU).

SDV See switched digital video (SDV).

second audio program (SAP) In an ATSC-encoded television sound carrier, a second monophonic audio stream—typically in a second language—delivered on the right channel of a stereo broadcast.

second harmonic A second harmonic is the second order beat whose two beating carriers have the same frequency.

second order beat The second order beat refers to an unwanted carrier created by two separate carriers beating against each other. These beating carriers may have the same or different frequencies.

Secured Socket Layer (SSL) The secured socket layer is used to define standard encryption software to pass sensitive information over an unsecured Internet connection. SSL works on encryption of sensitive data using complex techniques and converting them back to original data using keys on the receiving side.

segmentation Segmentation refers to determining the interests of smaller groups of a populace and finding ways to cater most significantly to one or more of them. This can include the time period that viewers and/or participants are most open for viewing a particular type of programming.

selective reception Selective reception is a characteristic of spatial processing that monitors
incoming signals and distinguishes between desirable information and interference. By filtering out interfering signals and appropriately combining the reception from all the antennas in the array, this approach provides significant improvement in signal quality.

server A server is a computer and/or software that provides and controls resources for clients on a network. These resources can include hardware devices such as printers and storage systems, or files as in the case of a Web server.

server clustering Server clustering is a network design in which all the servers on one or more rings are placed in a central location.

server farm A server farm is a network design in which a cluster of servers in a centralized location serve a wide user population.

service From the viewer’s point of view, a service is the television content-carrying entity that you can select by channel number. In conventional broadband communications, this is internally identified by a specific center frequency, and is selected by a channel number that is mapped to that frequency. The definition is expanded here to include any means of providing a service or carrying content that can be selected by channel number. For example, a service may use the tuner (or cause it to be used) to obtain analog channels, MPEG channels, or Vertical Blanking Interval (VBI) data. Alternatively, a service may use IP to get its data, and overlay this data on an analog program for presentation. See also Moving Picture Experts Group (MPEG), Internet Protocol (IP), and vertical blanking interval (VBI).

service access point (SAP) The service access point is the point at which services are provided by one layer, or sublayer to the layer immediately above it.

service control point (SCP) A service control point is a node within a signaling system number 7 (SS7) network that provides centralized service logic and data, such as call routing information.

service data unit (SDU) The service data unit is the information that is delivered as a unit between peer service access points (SAPs). See also service access point (SAP).

service descriptor Each service must have a service descriptor. A service descriptor contains the following: the service name, a description of the service, the service type, the service parameters, the display channel number, an application URL, and the application parameters. See also Uniform Resource Locator (URL).

service identifier (SID) A service identifier is an identifier appearing in the media access control
(MAC) allocation map message, which identifies the entities, which may use a particular upstream bandwidth assignment. A cable modem may have one or more unicast service identifiers. A group of cable modems may share a multicast service identifier. See also media access control (MAC) and cable modem.

service list A service list is a list of services from the service information (SI) database that have a given service type. A service list has an internal pointer to keep track of your location within the service list.

session initiation protocol (SIP) A session initiation protocol is an internet protocol used for negotiating multimedia sessions across the network.

set-top box A set-top box refers to any of several different electronic devices that may be used in a customer’s home to enable services to be on that customer’s television. If the set-top box device is used only for extending the channels available, it is called a converter. If it restores scrambled or otherwise protected signals, it is a descrambler.

shadow mask In a CRT color television receiver, the shadow mask sits between the electron guns and the phosphors on the inside of the screen. The shadow mask ensures that beams from each electron gun reach phosphors of the corresponding color only.

Shannon’s law Shannon’s law is an arithmetic proof that defines the maximum data rate an analog device can achieve when sending information over a sampled, analog-to-digital connection when the analog device has no control over the timing of each individual sample. For the North American telephone system, which has a sample rate of 8,000 samples per second with a range of up to 128 sample values, Shannon’s Law shows the maximum data rate that can be achieved over voice grade lines to be about 36Kbps.

shared wired network A shared wired network is a topology where multiple households connect
to a common piece of wire.

share Share refers to the percent of television households tuned to a particular program or category of programming.

shop-at-home Shop-at-home refers to programs that allow customers to view products and/or order them by cable television, including catalogs, shopping shows, etc.

side panels The side panels are used to refer to the black bars on the side of a television screen when the image of a standard 4:3 picture is displayed on a widescreen 16:9 aspect ratio television screen. These black bars are used to maintain the original aspect ratio of the source. See also aspect ratio.

signal In terms of interactive television, a signal is the electronic make up of the data, information, and/or message that is being transferred to you via a medium such as airwaves, satellite, telephone line, and cable. The term signal is often used interchangeably with content, although technically,
content more specifically refers to the theme or plot of the actual program.

signal leakage Signal leakage is the undesired emission of signals out of a cable television system.

signal splitter A signal splitter is a small electrical device that divides a television signal. A signal splitter could split an antenna signal into two parts for two televisions.

signal-to-noise ratio (SNR) The sensitivity of a communications receiver is generally specified in terms of the audio signal-to-noise ratio that results from an input signal of a certain number of microvolts.

signaling Signalling is the process by which an end system notifies a network that it wants service.

signalling rate The signalling rate refers to the maximum number of bits expressed in bandwidth that can ideally be transported over a given period of time over a system. The signalling rate is typically much higher than the average data transfer rate for the system due to various software and hardware
concerns.

Simple Mail Transfer Protocol (SMTP) The Simple Mail Transfer Protocol is a Transmission Control Protocol/Internet Protocol (TCP/IP) used to send email on a network or to route email on the Internet. See also Transmission Control Protocol/Internet Protocol (TCP/IP).

Simple Network Management Protocol (SNMP) The Simple Network Management Protocol (SNMP) allows a Transmission Control Protocol/Internet Protocol (TCP/IP) host running an SNMP application to query other nodes for network-related statistics and error conditions. The other hosts, which provide SNMP agents, respond to these queries and allow a single host to gather network statistics from many other network nodes. See also Transmission Control Protocol/Internet Protocol (TCP/IP).

simple profile A simple profile is when MPEG image streams use only I and P frames. A simple profile is less efficient than when coding includes B frames. See also Moving Picture Experts Group (MPEG), I frames, and P frames.

simplex transmission A simplex transmission is a data transmission that can occur in only one
direction on a given line.

simulcast Simulcast refers to the ability to broadcast the same program over two different transmission systems. Although not required by the Federal Communications Commission (FCC), most television stations will likely simulcast their digital television and analog signals as consumers will likely have analog televisions without a set-top box converter. See also Federal Communications Commission (FCC).

SIP See session initiation protocol (SIP).

skin effect The skin effect is the behavior whereby electricity migrates to the outside wall of a wire.

slice A slice is a series of macroblocks. It is the basic synchronizing unit for reconstructing the image data.

slope Slope refers to the difference in amplifier gain, or change in cable attenuation, between lowest and highest frequency present. See also amplifier, attenuation, and gain.

slope compensation Slope compensation is the action of a slope-compensated gain control, whereby slope of amplifier equalization is simultaneously changed with the gain so as to provide the correct cable equalization for different lengths of cable. Slope compensation is normally specified by range and tolerance.

small office/home office (SOHO) A small office/home office is an industry term used to refer to a
telecommunications market segment comprised of people working out of their homes or small offices.

SMATV See Satellite Master Antenna Television System (SMATV).

smear Smear describes a picture condition in which objects appear to be extended horizontally beyond their normal boundaries in a blurred or smeared manner.

SMG See subscriber media gateway (SMG).

SMPTE See Society for Motion Picture and TV Engineers (SMPTE).

SMS See spectrum management system (SMS).

SMTP See Simple Mail Transfer Protocol (SMTP).

SNAP See subnetwork access protocol (SNAP).

SNMP See Simple Network Management Protocol (SNMP).

snow Snow refers to heavy random noise that appears as salt and pepper on the television screen.

SNR See signal-to-noise ratio (SNR).

Society for Motion Picture and TV Engineers (SMPTE) The Society for Motion Picture and TV engineers is a professional society for motion picture and television engineers with more than 9000 members worldwide. It prepares standards and documentation for television production. SMPTE time code records hours, minutes, seconds, and frames on audio or videotape for synchronization purposes.

software development kit (SDK) A software development kit is the information, source code, and other data created for computer programmers to aid them in the use and/or development of a product.

SOHO See small office/home office (SOHO).

solid state Solid state is a term taken from physics, used interchangeably with the word transistorized. Solid state also includes other semiconductor elements, such as diodes. Generally, solid state refers to tubeless equipment.

SONET See Synchronous Optical NETwork (SONET).

Sony/Phillips Digital Interface (SPDI) Sony/Phillips Digital Interface is a digital interface for transmission of AC-3 audio in compressed digital form. See also Dolby AC-3.

source In PSM, each video or data stream being broadcast is referred to as a source. Each source is identified at the system layer by its source ID.

spacing Spacing refers to the length of cable between amplifiers expressed as dB loss at the highest television channel provided for in a system, equal to amplifier gain in main trunks.

spam Spam refers to receiving impersonal, indiscriminately sent out bulk email sales messages. Spam can include multiple postings in newsgroups.

span Span refers to the distance between line extenders or distribution amplifiers. Span also refers to the distance between taps. See also amplifier and tap.

spatial diversity Spatial diversity refers to an antenna configuration of two or more elements that are physically spaced—spatially diverse—to combat signal fading and improve signal quality. The desired spacing depends on the degree of multipath angle spread.

spatial division multiple access (SDMA) Spatial division multiple access (SDMA) is a complement (not an alternative) to CDMA and TDMA. This technology increases the number of users that can access an existing wireless phone or data system by exploiting the spatial characteristics of the channel itself through a highly developed implementation of an intelligent antenna system’s capabilities for receiving and transmitting.

spatial resolution Spatial resolution refers to the number of pixels vertically and horizontally
in a digital image. See also pixel.

SPDI See Sony/Phillips Digital Interface (SPDI).

special effects generator A special effects generator is a device permitting combinations of images
on a television screen supplied by one or more video inputs.

spectrum management system (SMS) A spectrum management system is a system for managing the radio frequency (RF) cable spectrum. See also radio frequency (RF).

splitter A splitter is a passive device—a device with no active electronic components—that distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.

sports blackout Sports blackout refers to the federal law that requires cable systems and television stations to delete coverage of local sports events to protect gate receipts.

spot revenue Spot revenue is revenue gained from advertising that is placed on a cable system by a local or national advertiser.

spread spectrum Spread spectrum enables the successful transmission to hostile transmission environments.

SRD See satellite relay distribution (SRD).

SSL See Secured Socket Layer (SSL).

staggercast Staggercast is used to designate the interval of time, in near-video-on-demand (NVOD); that is, the time between the beginning of a movie or program, on one channel and the beginning of the same program on another channel. For example, a movie starts at 7:00 on channel 50, at 7:15 on channel 51, at 7:30 on channel 52-the movie is staggercast 15 minutes. See also near-video-on-demand (NVOD).

standard definition television (SDTV) The term standard definition television is used to signify a digital television system in which the quality is approximately equivalent to that of National Television Systems Committee (NTSC). This equivalent quality may be achieved from pictures sourced at the 4:2:2 level of ITU-R Recommendation 601 and subjected to processing as part of the bit rate compression. The results should be such that when judged across a representative sample of program material, subjective equivalence with NTSC is achieved. Standard definition television is also called standard digital television. See also National Television Systems Committee (NTSC).

start bits The start bits are a sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock. This dictates the intervals at which individual bits are expected to be sent and received. See also stop bits.

statistical multiplexing Statistical multiplexing is done to increase the efficiency of a multiplex transmission. This is accomplished by varying the bit rate of each of the data transmissions in each of the channels that the transmission is occurring in. The benefit is that only the space in the channel needed at any given time is used instead of taking up more space in case of surges.

stickiness In terms of interactive television, stickiness refers to how well the features of the television system, subscription, value-added services, etc. keep the end user coming back for more. The time spent viewing the site is an indication of the interest level of the viewer. The higher the time spent viewing, the greater the stickiness of the site.

stop bits Stop bits are the sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock. This dictates the intervals at which individual bits are expected to be sent and received. See also start bits.

store and forward Store and forward refers to a technique for examining incoming packets on
an Ethernet switch or bridge whereby the whole packet is read before forwarding or filtering takes place. Store and forward is a slightly slower process than cut-through, but it does insure that all bad or misaligned packets are eliminated from the network by the switching device.

streaking Streaking is a term used to describe a picture condition in which objects appear to be extended horizontally beyond their normal boundaries.

stream A stream is an ordered series of bytes. The usual context for the term stream is the series of bytes extracted from transport stream packet payloads that have a common, unique PID value—for example, the video Packetized Elementary Stream (PES) packets or Program Map Table (PMT) sections.

streaming media Streaming media refers to the digital video, audio, and data services that are selectively delivered to individual users, either in response to a user request or based upon a user profile. These services are delivered over a data transport stream, either via real-time transmission to the user, or via off-peak data-carousel transmission to a storage device at or near the user’s location for subsequent retrieval.

sub A sub is an abbrevation for subscriber.

sub band Sub band refers to the frequency band from 6 MHz to 54 MHz. This band may be used for two-way data transmission.

subcarrier A subcarrier refers to one or more signals, more often audio, that is carried along side the main signal, such as a television signal.

sublayer A sublayer is a subdivision of a layer in the Open System Interconnection (OSI) reference model.

subnetwork Subnetworks are formed by connecting adjacent nodes physically with transmission links.

subnetwork access protocol (SNAP) The subnetwork access protocol is an extension of the LLC header to accommodate the use of 802-type networks as Internet Protocol (IP) networks. See also Internet Protocol (IP).

subscriber A subscriber is a household or business that legally receives and pays for cable and/or pay television service for its own use.

subscriber media gateway (SMG) A subscriber media gateway is a media gateway located within the subscriber’s network that bridges calls between the Internet Protocol (IP) network and the subscribers telephones or telephony-type devices. Typically, such a media gateway provides an external interface to one or more 2500-type telephony handsets and also supports common standard add-on devices such as caller ID display units and message waiting lights. See also Internet Protocol (IP).

subscriber unit The subscriber unit is the fixed, typically wall-mounted equipment used by the subscriber in a wireless local-loop system to send and receive messages. A standard telephone is attached to the subscriber unit by wire to complete the connection to the user.

subscription video-on-demand (SVOD) Subscription video-on-demand (SVOD) refers to subscription-based movies and/or programming. With subscription video-on-demand, a viewer can watch certain movies from a package at any time or join a movie that is already playing. Generally, movie/programming packages are scheduled events, but with subscription video-on-demand, subscribers can have access to certain movies/programming as part of a package for a fixed monthly fee. See also near-video-on-demand (NVOD) and video-on-demand (VOD).

subsplit Subsplit refers to a frequency-division scheme that allows bi-directional traffic on a single cable. Reverse path signals come to the head-end from 5 to 30 (up to 42 on extended subsplit systems) MHz. Forward path signals go from the head-end from 50 or 54 MHz to the upper frequency limit of the cable network. See also frequency and head-end.

subsystem A subsystem is an element in a hierarchical division of an open system that interacts directly with elements in the next higher division or the next lower division of that open system.

superband Superband refers to the band of cable television channels J through W lying between 216 and 300 MHz.

superstation Originally, superstation referred to television station WTBS in Atlanta. Superstation is now generally used to describe any broadcast television station that has its signal distributed nationally by satellite.

surfable channel A surfable channel is defined as a channel that would be presented to a subscriber who was channel surfing—that is, continuously pressing the Channel Up or Channel Down buttons. Surfable channels are essentially broadcast video services that do not require the downloading of an application to become active.

suspended application An application in the suspended state is loaded in to the set-top box’s
memory, but runs in the background so as to reduce its use of system resources. Any number of applications can be in the suspended state. An application may be in the suspended state either because it has been launched but not activated or because it has been suspended after being
launched and activated.

SVC See switched virtual circuit (SVC).

SVOD See subscription video-on-demand (SVOD).

sweetening Sweetening refers to improving the quality of an audio or video signal electronically by adding such data as sound effects, captions, or laugh tracks.

switch A switch is a mechanical or electric device that is used to deliberately interrupt or alter the path of the current through the circuit.

switched digital video (SDV) Switched digital video refers to the technology for sending, up on request, video through cable television or telephone lines.

switched network A switched network is any network in which switching is present and is used to direct messages from the sender to the ultimate recipient. Usually switching is accomplished by disconnecting and reconnecting lines in different configurations in order to set up a continuous pathway between the sender and the recipient.

switched service A switched service is a cable communications service in which each subscriber has a terminal and may communicate with any other subscriber.

switched virtual circuit (SVC) A switched virtual circuit is a circuit that allows an end-user to establish on-demand data connections between two end points on an ATM, Frame Relay, or X.25 network. See also asynchronous transfer mode (ATM).

switcher A switcher is a control that permits the selection of one image from any of several cameras to be fed into the television display or recording system.

switcher/fader A switcher/fader is a device permitting gradual, overlapping transition from the image of one camera to another. Sometimes, a switcher/fader is incorporated as part of a special effects generator.

sync Sync is an abbreviation for the words synchronization, synchronizing, etc. Synch applies to the synchronization signals, or timing pulses, which lock the electron beam of the picture monitors in step, both horizontally and vertically, with the electronic beam of the pickup tube. The color sync
signal in National Television Systems Committee (NTSC) systems is known as the color burst. See also color burst and National Television Systems Committee (NTSC).

sync compression Sync compressions refers to the reduction in the amplitude of the sync signal, with respect to the picture signal, occurring between two points of a circuit. See also amplitude and sync.

sync generator A sync generator is a device used to supply a common or master sync signal to a system of several cameras. This ensures that their scanning pulses will be in phase. Scanning pulses out of phase produce distortion or rolling, sometimes called sync loss.

sync level The sync level is the level of the tips of the synchronizing pulses.

Synchronous Optical NETwork (SONET) SONET is an optical interface standard to transport digital signals that allows inter-working of transmission products from multiple vendors. Among other things, it defines optical line rates known as optical carrier (OC) signals. The base rate is 51.84Mbps (OC-1), with higher rates being direct multiples of the base rate. For example, OC-3 runs at 155.52 Mbps, or three times the rate of OC-1.

synchronous transmission protocol A synchronous transmission protocol is a method of encoding a data transmission that does not use start and stop bits at the beginning and end of each byte to synchronize the data time clocks at each end of a connection. Instead, it sets its timing signal at the beginning and end of each connection, and corrects discrepancies that arise over time by using
the changing values each device on the connection sends and receives to keep their clocks in sync. Eliminating the start and stop bits reduces the overhead required to transmit each byte, and allows for increased throughput. See also start bits and stop bits.

syndicated exclusivity Syndicated exclusivity is a requirement by which cable systems must black
out significant portions of their distant signals in order to protect syndicated programming offered by local television broadcasters under an exclusive contract. The Federal Communications Commission (FCC) eliminated this requirement in 1980 and re-imposed it in 1990. See also Federal Communications Commission (FCC).

system clock reference (SCR) The system clock reference is a time stamp in the program stream from which the decoder timing is derived.

system integrators (SI) System integrators are companies that provide installation of networking equipment and possibly other services such as training or network management.

system level System level refers to the level of signal in a cable television system at the output of each amplifier. The system level must be carefully chosen and maintained for least distortion and noise.

system loss Cable television distribution systems are designed to compensate the cable and device losses. The spacing between cable amplifiers can increase as system losses are minimized through the proper choice of connectors, cable and related hardware. System losses are referred to as a dB of cable without reference to specific cable size or device losses. Generally, these losses are understood to be at the highest operating frequency of the system.

system noise System noise refers to the random energy generated by thermal and shot effects in the system. It is specified in terms of its rms level as measured in a 4-MHz bandwidth centered within a 6-MHz cable television channel.

system operator A system operator is the individual, organization, company, or other entity that operates a cable television system.

system test plan A system test plan is a plan or policy for verifying system function, performance, and/or compliance to a specification.

systems management System management refers to functions in the application layer related to the management of various Open Systems Interconnection (OSI) resources and their status across all layers of the OSI architecture.

take rate Take rate is the ratio of homes that pay for a cable service to homes passed.

tap A tap is a device which splits off a portion of the feeder line signal for the subscriber. See also subscriber.

TAR See total activity report (TAR).

target market A target market is the total number of possible customers you could sell your products/services to.

targeted advertising Targeted advertising refers to advertising geared towards a more specific audience. Responses to the advertising can be measured, which can provide advertisers with a better understanding of what would sell and what would not.

t-commerce Television commerce, or t-commerce, is an interactive television application that enables electronic transactions between businesses and consumers via television.

TCP See Transmission Control Protocol (TCP).

TCP/IP See Transmission Control Protocol/Internet Protocol (TCP/IP).

TDD See time division duplex (TDD).

TDMA See time division multiplexing access (TDMA).

tearing Tearing is a term used to describe a picture condition in which groups of horizontal lines are displaced in an irregular manner. Tearing is caused by lack of horizontal synchronization.

telecommunications Telecommunications refers to communicating over a distance through wire, radio, optical, or other electromagnetic means.

teletext Teletext is the broadcast service using several otherwise unused scanning lines—vertical blanking intervals—between frames of television pictures to transmit information from a central database to receiving television sets. See also vertical blanking interval (VBI).

television households Television households refers to households having one or more television sets. Estimates for each county are based on an updating of American Research Bureau (ARB) television penetration estimates. The number of households that watch television in any locality during prime-time hours determines the top 100 markets for Federal Communications Commission (FCC) cable rules. See also Federal Communications Commission (FCC).

television market A television market is a city or complex of closely associated cities served by commercial television broadcast signals from one or more television stations located within the area. The Federal Communications Commission (FCC) uses television markets for designating what kind of cable services an operator should provide in terms of signal carriage and non-broadcast channel use. See also Federal Communications Commission (FCC).

television receiver-only (TVRO) A television receiver-only (TVRO) refers to the receiving antenna dish, or complete package or dish receiver.

telnet Telnet is a Transmission Control Protocol/Internet Protocol (TCP/IP) protocol that allows terminal-type login access to computers on the Internet for the purpose of entering remote commands. The protocol name is capitalized. When used in the form telnet, it refers to the client software that implements the protocol, or the act of using the protocol.

terminal Generally, terminal refers to the connection point of equipment, power, or signal. It can also refer to any terminating piece of equipment, such as a computer terminal.

terminator A terminator refers to a resistive load for an open coaxial line to eliminate reflections. Usually, a terminator is capacitively coupled to avoid shorts in cable-powered systems.

thick client Thick client refers to the concept of robust computer processing power, storage, and memory within the end users set top box or PC client. Software application(s) can and usually reside at the users location. Thick clients are also refered to as heavy clients. See also thin client.

thickwire Thickwire refers to half-inch diameter coax cable. See also coaxial cable and thinwire.

thin client Thin client refers to the concept of minimizing required storage, memory, and computing horsepower at the user location by performing computing and storing information in a central location, with connections for user input and display over a medium-speed network. See also thick client.

thinwire Thinwire refers to thin coaxial cable similar to that used for television and other video hookups. See also coaxial cable and thickwire.

third harmonic A third harmonic refers to a third order beat whose three beating carriers all have the same frequency. See also third order beat.

third order beat A third order beat is an unwanted carrier created by three separate carriers beating against each other. These beating carriers may have the same or different frequencies. See also second order beat.

threshold Threshold refers to the minimum level at which a signal of any kind can be detected, either by the human senses or by using any electronic instrument.

throughput Throughput refers to the speed at which the data is received. Throughput can be increased by compressing data before it is transmitted, then decompressed when it is received, or by using a more efficient transmission protocol.

tick Ticks are the 6.25-microsecond time intervals that are the reference for upstream mini-slot definition and upstream transmission times.

tiered programming Tiered programming refers to a group of programs for which the customer is charged a fee. For example, most cable systems offer a satellite programming tier.

tiering Tiering refers to supplying cable subscribers with one or more program services beyond the basic offerings at an extra charge. Each additional price increment is called a tier.
tilt Tilt refers to the maximum difference in transmission gain of a cable television system over a given bandwidth—typically the entire forward operating frequency range.

time division duplex (TDD) Time division duplex (TDD) is the method of multiplexing transmit/
receive (uplink/downlink) parts of a wireless communications link together. The exchange of uplink and downlink information takes place on the same frequency, but is distinguished by time-slot characteristics. See also frequency division duplex (FDD), downlink, and uplink.

time division multiplexing access (TDMA) Time division multiplexing access (TDMA) is a digital technology that enables a large number of users to access, in sequence, a single radio frequency channel without interference by allocating unique time slots to each user within each channel. See also radio frequency (RF).

TiVo TiVo is one of two major companies offering personal video recorders. See also ReplayTV and personal video recorder (PVR).

token A token is the character sequence or frame, passed in sequence from node to node, to indicate that the node controlling it has the right to transmit for a given amount of time.

token ring Developed by IBM, a token ring is a 4 or 16 Mbps network that uses a ring topology and a token-passing access method.

top 100 market A top 100 market refers to the ranking of largest television broadcast areas by size of market; that is, number of viewers and television households. It is used in Federal Communications Commission (FCC) rulemaking and in selling of airtime to advertisers. See also Federal Communications Commission (FCC) and television households.

topology The topology is the arrangement of the nodes and connecting hardware that comprises the network. Types of topology include ring, bus, star, and tree.

total activity report (TAR) A total activity report is a quarterly Nielsen report that lists all the television activity during a sweep, including broadcast stations, basic cable, pay cable, and superstations. It shows household rating and share delivery by day part in both the DMA (total market) and cable household universe for all program sources. See also superstation.

traffic parameter A traffic parameter specifies a particular traffic aspect of a connection.

transceiver A transceiver is a combination of a transmitter and a receiver having a common frequency control and usually enclosed in a single package. Transceivers are extensively used in two-way radio communications at all frequencies.

transducer A transducer is a device that converts one form of energy or disturbance into another. Transducers convert AC and DC into sound, radio waves, or other forms.

transistor A transistor is a semiconductor device consisting of three or four layers used for switching or amplification at frequencies ranging from direct current to ultra-high.

translator A translator is a relay system that picks up distant television signals, converts the signals to another channel to avoid interference, and retransmits them into areas that the original television signal could not reach.

Transmission Control Protocol (TCP) Transmission Control Protocol (TCP) is a transport-layer Internet protocol that ensures successful end-to-end delivery of data packets without error.

Transmission Control Protocol/Internet Protocol (TCP/IP) Transmission Control Protocol/Internet Protocol (TCP/IP) is the most common protocol used for communication between computers on a network. It was originally developed by the US Department of Defense for a worldwide communications network that eventually developed into the Internet.

transmission convergence sublayer The transmission convergence sublayer is the sublayer of the physical layer that provides an interface between the data link layer and the physical media dependent (PMD) Sublayer.

transmission medium The transmission medium refers to the material on which information signals may be carried. Examples of transmission mediums include optical fiber, coaxial cable, and twisted wire pairs.

transmission system The transmission system refers to the interface and transmission medium through which peer physical layer entities transfer bits.

transponder The transponder is that part of a satellite that receives and transmits a signal.

transport A transport is a unique means of media delivery. Each transport has a different combination of ownership and technical capability that determines what types of media are delivered.

transport A Transport A is part of the nomenclature used in the Advanced Television Enhancement Forum (ATVEF) specification to denote the means by which the enhanced content is delivered to the set-top box. Transport A denotes delivery of the enhanced content via the internet, either via a traditional modem or broadband connection. Transport A is generally used for a wide array of less popular content that would exceed the data-broadcast bandwidth and cache size. See also Advanced Television Enhancement Forum (ATVEF) and transport B.

transport B Transport A is part of the nomenclature used in the Advanced Television Enhancement Forum (ATVEF) specification to denote the means by which the enhanced content is delivered to the set-top-box. Transport B denotes delivery of enhanced content via a data broadcast. Transport B is generally used for a smaller amount (1MB in ATVEF) of highly popular content. See also Advanced Television Enhancement Forum (ATVEF) and transport A.

transport stream In MPEG-2, the transport stream refers to a packet-based method of multiplexing one or more digital video and audio streams having one or more independent time bases into a single stream. See also MPEG-2 and multiplex.

trigger A trigger is an event that may cause a change in the behavior of a DVB-HTML application that registers interest in such events. Triggers may come from many sources—for example, the broadcast stream—or may be generated from other data such as the system clock, or may be generated as a result of user interaction.

triple beat A third order beat whose three beating carriers all have different frequencies, but are spaced at equal frequency separations. See also third order beat.

trivial file transfer protocol (TFTP) The trivial file transfer protocol is an Internet protocol for transferring files without the requirement for user names and passwords that is typically used for automatic downloads of data and software.

trunk A trunk is an analog or digital connection from a circuit switch that carries user media content and may carry telephony signaling (MF, R2, etc.). Digital trunks may be transported and may appear at the media gateway as channels within a framed bit stream. Trunks are typically provisioned in groups, each member of which provides equivalent routing and service.

trunk amplifiers Trunk amplifiers are the amplifiers along the trunk line responsible for maintaining signal strength that must have low distortion, low noise, and moderate gain. Degradation of the signal along the trunk cannot be corrected downstream. In fact, cascade amplifiers with similar faults simply amplify the fault. Trunk amplifiers compensate for cable losses with automatic slope control (ASC) and automatic gain control (AGC).

trunk cable A trunk cable carries the signal from the head-end to groups of subscribers. The cables can be either coaxial or fiber depending on the design of the system.

trunk circuit A trunk circuit is the part of a switching system that is associated with the connection of a trunk to the switching system. It converts between the signal formats used internally in the switching system and those used in the transmission circuit, and it performs logic and sometimes memory functions associated with supervisors.

trunk line A trunk line is the major distribution cable used in cable television. It divides into feeder lines which are tapped for service to subscribers.

trunking Trunking refers to transporting signals from one point—an antenna site for instance—to another point—such as a head-end, usually without serving customers directly. Trunking can be accomplished using coaxial cable, fiber optics, or microwave radio. See also coaxial cable and fiber optics.

tune From the viewer’s standpoint, tune means to select a channel—for example, tune to channel 9. This term stems from analog broadband systems, but is such a familiar term that it would seem best to keep it, even though it is no longer accurate.

TV penetration TV penetration refers to the percentage of homes having one or more television sets at the time of the American Research Bureau (ARB) survey. The ARB surveys local markets from October through July, and the number of surveys in a year depends on the size of the market.

TVRO See television receiver-only (TVRO).

twisted pair Twisted pair refers to a pair of wires used in transmission circuits and twisted about one another to minimize coupling with other circuits. Paired cable is made up of a few to several thousand twisted pairs.

two-way Two-way refers to bidirectional communications over the same communication medium.

two-way capacity A cable television system with two-way capacity can conduct signals to the head-end as well as away from it. Two-way or bi-directional systems now carry data. Eventually, these systems may carry full audio and video television signals in either direction.

two-way system A two-way system refers to the ability to receive television programming through the broadband network and send information back through the same network. Customers use this capability to order movies and music and to interact in other manners with the broadband network. See also one-way system.

typical operating conditions Typical operating conditions refer to the optimum operating conditions for a stated number of channels.

UART See universal asynchronous receiver transmitter (UART).

UBR See unspecified bit rate (UBR).

UDP See User Datagram Protocol (UDP).

UHF See Ultra High Frequency (UHF).

Ultra High Frequency (UHF) Ultra High Frequency (UHF) refers to channels above channel 13—or from 470 MHz to 806 MHz.

unassigned channel An unassigned channel is a channel number to which the cable operator
has not assigned a channel. If the viewer selects an unassigned channel, a reasonable default behavior is exhibited.

Uniform Resource Locator (URL) The Uniform Resource Locator (URL) is the address of an Internet site. The URL contains the protocol used for the site—such as http or ftp, the domain name, or IP address of the site. For example, optionally, the folder or page on the site where specific information is stored.

universal asynchronous receiver transmitter (UART) A computer’s UART chip dictates the maximum rate a computer can send and receive data over its serial ports.

universal serial bus (USB) A universal serial bus is a plug-and-play standard for connecting multiple
(up to 127) input/output devices to a single high-bandwidth port. The design of the bus allows hot-swapping of the devices—that is, disconnection and reconnection without powering the computer off—and automatic configuration. The USB peripheral bus standard was developed by Compaq, IBM, DEC, Intel, Microsoft, NEC, and Northern Telecom. See also plug-and-play.

unspecified bit rate (UBR) The unspecified bit rate (UBR) service class is intended for delay-tolerant or non-real-time applications, or those which do not require tightly constrained delay and delay variation.

upconverter An upconverter is a device used to add a lower frequency to a microwave frequency.

uplink Uplink refers to the return signal from the user to the base station. See also downlink.

uploading Uploading refers to the transfer of files from a local computer up to a remote computer. See also download.

upstream Upstream is the term used to describe traffic and paths that go from the subscriber to the head-end. It is also known as reverse path or return path.

URL See Uniform Resource Locator (URL).

USB See universal serial bus (USB).

User Datagram Protocol (UDP) User Datagram Protocol (UDP) is a protocol residing on top of Internet Protocol (IP) that is used for end-to-end transmission of user messages. Unlike Transmission Control Protocol (TCP), UDP is an unreliable protocol, which means that it does not contain any retransmission mechanisms. Thus, UDP packets are not guaranteed to make it through the network. See also Internet Protocol (IP) and Transmission Control Protocol (TCP).

VAR See value-added reseller (VAR).

value-added reseller (VAR) Value-added reseller refers to distributors that also provide other services such as systems integration or network management.

variable bit rate (VBR) Variable bit rate is a type of telecommunications service characterized by a service bit rate specified by statistically expressed parameters that allow the bit rate to vary within defined limits.

VBI See vertical blanking interval (VBI).

VBR See variable bit rate (VBR).

VCT See Virtual Channel Table (VCT).

VDSL Very high-speed digital subscriber line that uses existing the copper infrastructure of the telephone companies. VDSL offers video and data transmission rates up to 52 Mbps up to 2,700 feet. See also digital subscriber line (DSL).

velocity of propagation Velocity of propagation refers to the velocity of signal transmission. In free space, electromagnetic waves travel with the speed of light. In coaxial cables, this speed is reduced. The velocity of propagation is commonly expressed as percentage of the speed in free space.

vertical blanking interval (VBI) The vertical blanking interval is the unused lines in each field of a television signal, seen as a thick band when the television picture rolls over. Some of these lines may be used for teletext and captioning, or may contain specialized data. See also teletext.

Very High Frequency (VHF) Very High Frequency (VHF) refers to channels 2-13—54-88 MHz and 174-216 MHz.

very small aperture terminal (VSAT) Very small aperture terminals are small earth stations with a satellite dish usually four to six feet in diameter used to receive high speed data transmissions. VSATs can also transmit slow-speed data. See also earth station.

vestigial sidebandtransmission A vestigial sideband transmission is a system of transmission that eliminates a large portion, but not all, of one sideband of an amplitude modulated signal. Vestigial sideband transmissions may be done with either analog or digital modulation. The vestigial sideband can be used to carry new information. For example, the broadcast industry uses vestigial sideband with eight discreet amplitude levels (8-VSB) for modulating standard- and high-definition digital television signals transmitted from a broadcast tower.

VHF See Very High Frequency (VHF).

video Video generally refers to the bandwidth and spectrum of the signal that results from television scanning and which is used to produce a picture.

video band The video band refers to the frequency band used to transmit a composite video signal. See also composite video signal.

video transmission Video transmission refers to the original video signal before it is modulated and converted to radio frequency and broadcast or cablecast. A home television set reconverts radio frequencies to a video signal. See also broadcast, cablecasting, and radio frequency (RF).

video-on-demand (VOD) Video-on-demand allows a subscriber to select movies he or she wishes to view from a large selection of titles and categories stored on a remote server at any time. This service may also provide VCR functionality—stop, pause, etc.—that allows the subscriber to control the play back of the server from the remote control.

video tape recorder (VTR) A video tape recorder is a device that allows the recording and playback of magnetic tape sound and picture recordings.

videotape Videotape is used to electronically record sight and sound for instant playback. Videotape comes in half-inch, three-quarters, one, and two-inch widths and can be erased and re-recorded.

videotex Videotex is the generic term used to refer to a two-way interactive system for the delivery of computer-generated data into the home, usually using the television set as a display device. Some of the more often used specific terms are viewdata for telephone-based systems (narrowband interactive systems); wideband broadcast or cabletext for systems using a full video channel for information transmission; and wideband two-way teletext for systems which could be implemented over two-way cable television systems. In addition, hybrids and other transmission technologies, such as satellite, could be used for delivery of videotex services on a national scale.

viewer A viewer is the person currently in control of the set-top box. This term may just refer to whoever is holding the remote, but has other implications when viewer profiles are used.

viewer profile A viewer profile allows the viewing experience to be personalized for each viewer. Each viewer may have personal favorite channels and certain other settings. Some features, such as parental controls, may be extended to allow a personal viewing and purchasing PIN for each viewer.

viewer session Viewer session refers to all set-top box viewer activities between the start of a session and the end of a session. These events may be different, depending on whether individual viewer profiles are provided.

viewers per viewing household (VPVH) Viewers per viewing household (VPVH) is a demographic percentage that indicates how many persons per 100 or per 1000 households are viewing. For example, a VPVH of 80 K2-11 means that for every 100 households viewing, there are an estimated 80 children ages 2 to 11.

violence chip (V-chip) A V-chip is a microchip that permits parental control over rated television programs.

virtual channel A virtual channel is the communication channel that provides for the sequential unidirectional transport of ATM cells.

Virtual Channel Table (VCT) The Virtual Channel Table is broadcast by the head-end and read by the tuner manager during the boot process. The VCT is defined by the Advanced Television Systems Committee (ATSC). Basically, the VCT contains the following information:
◆ a transport stream identifier
◆ the channel number
◆ the short channel name
◆ the carrier frequency
◆ the program number
◆ the access controlled flag
◆ the location field for extended text messages
◆ the service type

virtual circuit Virtual circuit refers to a predefined path through a network that provides a connection-oriented session between two applications.

virtual machine A virtual machine is an operating environment working with, yet independent of a host operating system. Used in such applications as a middleware component of a set-top box, virtual machines accommodate proprietary philosophies of associated software and service vendors.

virtual private network (VPN) A virtual private network (VPN) is a portion of a public network that has been logically partitioned for private use. It is a type of technology designed to increase the security of information transferred over the Internet. VPN can work with either wired or wireless networks, as well as with dial-up connections over Plain Old Telephone Service (POTS). VPN creates a private encrypted tunnel from the end user’s computer, through the local wireless network, through the Internet, all the way to the corporate servers and database. See also Plain Old Telephone Service (POTS).

VOD See video-on-demand (VOD).

voice-over-internet potocol (VoIP) Voice-over-internet protocol (VoIP) services are a provision of voice telephony via the use of packet-switched networks running Internet Protocol (IP) networks rather than traditional circuit switching. VoIP can be less expensive than voice transmission using standard analog packets over Plain Old Telephone Service (POTS). See also Plain Old Telephone Service (POTS).

Voice-Over-Net (VON) Voice-Over-Net refers to various sets of technologies that are used to
enable voice applications across the Internet.

VoIP See voice-over-internet potocol (VoIP).

VON See Voice-Over-Net (VON).

VPN See virtual private network (VPN).

VPVH See viewers per viewing household (VPVH).

VSAT See very small aperture terminal (VSAT).

VSB-8 VSB-8 is vestigial sideband modulation with 8 discrete amplitude levels.

VTR See video tape recorder (VTR).

walled garden A walled garden refers to a limited number of Web pages or similar content that a content provider offers their customers. By limiting Internet access to selected sites, it can be more appreciated by users as Web pages viewed on television often do not support software applications such as Java and Flash and can be difficult to navigate with a remote control.

WAN See Wide Area Network (WAN).

watch & record Watch & record refers to the use of two set-top boxes in a master-slave configuration to permit viewing and recording two different programs.

watermarking Watermarking is a technique used to hide a small amount of digital data in a digital signal in a way that it cannot be detected by a standard playback device or viewer.

waveform A waveform is a graphical representation of the rise and fall of the electrical potential (voltage) on a pair of wires or some other signal over time. In telephony, analog waveforms are translated into a series of binary values, called samples. These samples are taken 8000 times a second, sent on to their destination, where they are translated back into a series of 8000 changes in voltage that almost resembles the original analog signal.

wavelength division multiplexing (WDM) Wavelength division multiplexing refers to technology that enables the capacity of fiber optic lines to be increased exponentially through the use of different frequencies (or colors). As more colors are used, more unique communication paths are created. See also fiber optics.

WDM See wavelength division multiplexing (WDM).

Wide Area Network (WAN) A wide area network is a computer network that usually spans larger geographic area, such as cities, counties, states, and/or nations. WAN’s usually employ telephone-type topologies, like T1, T2, T5, ATM, etc. See also local area network (LAN).

wideband Typically, the term wideband represents a medium intermediate between narrowband and broadband. Wideband can transmit at more than 64 Kbps and less than 1.5 Mbps. See also broadband and narrowband.

wide screen Wide screen refers to a television signal with a wider picture of 16:9 aspect ratio instead of the conventional 4:3. See also aspect ratio.

Wi-Fi Wi-Fi is an interoperability certification for wireless local area network (LAN) products based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. See also local area network (LAN) and Institute of Electrical and Electronic Engineers (IEEE).

windshield wiper effect The windshield wiper effect is the onset of overload in multichannel cable television systems caused by cross-modulation, where the horizontal sync pulses of one or more television channels are superimposed on the desired channel carrier. Both black and white windshield wiping are observed and are caused by different mechanisms. See also cross-modulation.

wired city Wired city refers to the concept of television and other communications data, educational material, instructional television, and information retrieval service that wired services can provide. Broadcast services must, of necessity, be limited by scarce spectrum space; wired services have theoretically unlimited channel capacity.

wireless cable Wireless cable uses microwaves frequencies to transmit programming to a small antenna at a subscriber’s home.

xDSL xDSL is the general term applied to a whole family of high-speed digital data products. The letters DSL stand for Digital Subscriber Line. The x is a place keeper for the term describing the type of DSL connection:
◆ A for Asymmetric
◆ H for High Speed
◆ I for ISDN
◆ S for Symmetric
These new technologies, ADSL, HDSL, IDSL, and SDSL are expected to be the next-generation high-speed data products that will someday replace existing technologies like ISDN and Fractional T-1 lines.

zero cells Zero cells is a phenomenon common to local market cable television ratings. In this case, the Nielsen household meter indicates viewing, but the corresponding diary data shows no record of viewing.

Z-order Z-order refers to the order in which panels were attached to a screen. The panel in the front is closest to the viewer