The Cable Center

This glossary of cable and telecommunications terms is intended to enhance your understanding of this dynamic industry. We are able to present this information with the generous help of CableLabs - consult their website for the most up-to-date information about cable technology.

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Abstract Service
A mechanism to group a set of related unbound applications where some aggregator has taken the responsibility to ensure that the set of related applications work together. This is a generalization of a broadcast service to support applications not related to any broadcast TV service. A set of resident applications which an MSO has packaged together (e.g. chat, email, WWW browser) could comprise one abstract service.

Abstract Windowing Toolkit (AWT)
A Java package that supports graphical user interface (GUI) programming.

Acceptance Test Plan (ATP)
is a compendium of test procedures that may be used to demonstrate compliance with certain specifications.

Access Channels
Channels set aside by the cable operator for use by the public, educational institutions, municipal government, or fore lease on a non-discriminatory basis.

Access Control
Limiting the flow of information from the resources of a system only to authorized persons, programs, processes, or other system resources on a network.

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

Access Node (AN)
Part of the Access Network which performs some or all of the following: modulating forward data onto the Access Network; demodulating return-path data; enforcing the Media Access Control (MAC) protocol for access onto the Access Network; separating or classifying traffic prior to 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.

Active
A service flow is said to be “active” when it is permitted to forward data packets. A service flow must first be admitted before it is active.

Active Circuit
Powered circuitry containing transistors, such as amplifiers, power supplies or converters.

Active Serive Flow
An admitted Service Flow from the Cable Modem (CM) to the Cable Modem Termination System (CMTS) which is available for packet transmission.

Ad avails
Advertising spots available to a cable operator to insert local advertising on a cable network.
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.

Additional Call Offering (ACO)
An ISDN provisioning option that instructs the telephone company’s Central Office switch to alert a customer’s terminal adapter that a second phone call is being placed to one of the phone numbers the adapter services which is already in use. Sometimes erroneously called FCO or Flexible Call Offering.

Address Resolution Protocol (ARP)
A protocol of the IETF for converting network (IP) addresses to 48-bit Ethernet addresses.

Addressable
Able to signal from the headend or hub in such a way that only the desired subscriber’s receiving equipment is affected. In this way, it is possible to send a signal to a single subscriber and effect changes in the subscriber’s level of service.

Adjacent Channel
Any of two TV 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.

Admitted
A service flow is said to be “admitted” when the Cable Modem Termination System (CMTS) has reserved resources (e.g., bandwidth) for it on the Data Over Cable Service Interface Specification (DOCSIS®) network.

Admitted Service Flow
A Service Flow, either provisioned or dynamically signaled, which is authorized and for which resources have been reserved but may or may not be active.

Advanced Television System Committee (ATSC)
An organization founded in 1983 to research and develop a digital TV standard for the U.S. Or an international organization of 200 members that is establishing voluntary technical standards for advanced television systems.

Advanced Television Enhancement Forum (ATVEF)
A consortium of broadcast, cable and computer companies founded in 1998 that developed the ATVEF Enhanced Content Specification, an HTML and JavaScript-based format for adding content to interactive TV. ATVEF closed at the end of 1999 and turned over the specification to the ATV Forum and SMPTE. Or across-industry alliance of companies that has defined protocols for Hypertext Markup Language (HTML)-based enhanced television, which allow content creators to deliver enhanced programming to intelligent receivers.

Adaptive Timeout
Retry with exponential timeout: 1st attempt – 1 sec and the last attempt – 16 secs.

Aerial Plant
Cable that is suspended in the air on telephone or electric utility poles.

A-link
A-Links are SS7 links that interconnect STPs and either SSPs or SCPs. ‘A’ stands for “Access.”

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

Allocations
The assignments of frequencies by the FCC for various communications uses (e.g., television, radio, land-mobile, defense, microwave, etc.) to achieve fair division of the available spectrum and minimize interference among users.

Alternative access provider
A telecommunications firm, other than the local telephone company, that provides a connection between a customer’s premises to a point of presence of the long distance carrier.

American National Standards Institute (ANSI)
A US standards body.

Amplifier
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 headend.

Amplitude Modulation
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.

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. An analog telephone line is referred to as a Plain Old Telephone Service (POTS) line. Traditional form of telecommunications transmission in a constant variable wave, rather than in packet-based (or digital) form. See also modem and digital.

Analog Device
A device that operates with variables represented by continuously measured quantities such as voltages, resistances, rotations and pressures.

Analog Signal
A signal that is solely dependent on magnitude to express the information content.

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

Antenna
A structure or device used to receive or transmit electromagnetic waves.

Antenna Array
A group of identical antennas arranged and interconnected for achieving greater directivity (gain) or beam shaping.

Antenna Preamplifier
A small amplifier, usually mast-mounted, for amplifying weak signals to a level sufficient to compensate for down-lead losses and to supply sufficient input to system control devices.

Antenna Stack
Antenna tower with multiple antennas and supports.

Anti-Siphoning
FCC rules which prevent cable systems from “siphoning off” programming for pay cable channels that otherwise would be seen on conventional broadcast TV. “Anti-siphoning” rules state that only movies no older than three years and sports events not ordinarily seen on television can be cablecast.

Application
An application is a functional implementation realized as software running in one or spread over serveral interplaying hardware entities.

Application boundary
A concise general description of the data elements (HTML documents, code files, images, etc.) used to form one application and the logical locator of the entry point, the application boundary is described by a regular expression over the URL language. Where no such boundary is drawn, the default boundary shall be the entire set of documents that the OpenCable platform can access.

Application Information Table (AIT)
Provides information about the activation state of service bound applications.

Application manager
The application manager is the entity in the OpenCable Application Platform that is responsible for managing the lifecycle of the applications. It manages both the bound and unbound applications.

Application Platform
An application platform is the collection of application program interfaces and protocols on which content and applications are developed.

Application Program Interface (API)
An application program interface is the software interface to system services or software libraries. An API can consist of classes, function calls, subroutine calls, descriptive tags, etc.

Aspect Ratio
The aspect ratio refers to the ratio of width to height of a picture. Standard definition television uses a 4:3 aspect ratio. High definition television uses a 16:9 aspect ratio.

Asymmetric Connection
A connection where data can flow in one direction at a much higher speed than in the other. Some examples of asymmetric connections are ADSL, 56K Modems, and satellite downlinks. See also back channel.

Asymmetric Digital Subscriber Line (ADSL)
ADSL is a data communications technology that can “piggyback” a standard voice telephone connection and a high-speed (up to 8Mbps) digital data link on to a single pair local loop connections to a customer premises. ADSL technology is an asymmetric technology, meaning 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 128Kbps of outbound bandwidth, but may be able to receive data at speeds of 8Mbps. See DSLAM, NID, and xDSL.

Asymmetric Key
An encryption key or a decryption key used in public key cryptography, where encryption and decryption keys are always distinct.

Asynchronous
A type of transmission in which each character is transmitted independently without reference to a standard clock; uses stop and start bits.

Asynchronous Transfer Mode (ATM)
The transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic. Or a protocol for the transmission of a variety of digital signals using uniform 53-byte cells.

Asynchronous Transmission Protocol
A method of encoding a data transmission that 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. This increases the “overhead” required to transmit each byte and decreases throughput. See also Synchronous Transmission Protocol.

ATM Cell
A digital information block of fixed length (53 octets) identified by a label at the ATM layer.

Attenuation
The decrease in amplitude of a signal between any two points in a circuit. Usually expressed in decibels. Attenuation is the opposite of amplification.

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

Audio
Relating to sound or its reproduction; used in the transmission or reception of sound.

Audio Server
An Audio Server plays informational announcements in PacketCable network. Media announcements are needed for communications that do not complete and to provide enhanced information services to the user. The component parts of Audio Server services are Media Players and Media Player Controllers.

Automatic Gain Control (AGC)
A circuit which automatically controls the gain of an amplifier so that the output signal level is virtually constant for varying input signal levels.

Automatic Gain Control (AGC) Threshold
The level of input current at which the AGC circuit becomes active.

Automatic Gain Control (AGC) Time Constant
The amount of time it takes to achieve the required AGC level; also the amount of time it takes to recover from AGC.

Authentication
The process of verifying the claimed identity of an entity to another entity.

Authenticity
The ability to ensure that the given information is without modification or forgery and was in fact produced by the entity that claims to have given the information.

Authorization
The act of giving access to a service or device if one has permission to have the access.

Authorization Module
The authorization module is an abstract module that the Cable Modem Termination System (CMTS) can contact to authorize Service Flows and Classifiers. The authorization module tells the CMTS whether the requesting Cable Modem (CM) is authorized for the resources it is requesting.

Automatic Slope Control (ASC)
Circuitry which permits amplifier response compensation for varying slope (tilt) at its input.

Availability
In cable television systems, availability is the long-term ratio of the actual RF channel operation time to scheduled RF channel operation time (expressed as a percent value) and is based on a bit error rate (BER) assumption.

Available Bit Rate (ABR)
An ATM layer service where the limiting ATM-layer transfer characteristics provided by the network may change subsequent to the connection established.

Average revenue per unit (ARPU)
Commonly used a financial benchmark in the cable industry to measure average revenue per cable subscriber.