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.vidiom.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.vidiom.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.vidiom.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-