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One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 1000 Mbps (baseband) carried over twisted pair. Also known as Gigabit Ethernet or GigE.
One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 100 Mbps (baseband) carried over twisted pair. Also known as Fast Ethernet.
One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 10 Mbps (baseband) carried over twisted pair.
Short for 2 Binary, 1 Quartinary. 2B1Q is a full-duplex digital signaling technique used by many digital communications technologies (like ISDN) to send data over a single pair of wires. It uses a system of three different voltages: one for each of the two binary states (the 2B part of "2B1Q") and a third, quartinary voltage that indicates both ends of the data connection are sending the same binary value.
56Kbps Modems
More appropriately called Pulse Code Modulation (PCM) Modems, these 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 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 they are translated into a specific series of voltage changes that a PCM modem knows how to interpret. Data sent out by a 56Kbps modem is subject to the same physical restrictions of any modem, so its top "back channel" speed is 33.6Kbps. 56Kbps modems are built against the ITU-T V.90 or V.92 standards.
Refers to the five founding companies of the Digital Transmission Content Protection (DTCP) technology. Sony, Matsushita, Intel, Toshiba and Hitachi. Also used to refer to 5C digital certificates.
A telephone company central office switch manufactured by Lucent Technology (an AT&T spin-off company) which has ISDN and other digital telephony capabilities. Frequently abbreviated to 5E. See also DMS-100.
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, e-mail, 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)
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 Quos guarantees from traffic that receives best-effort support; enforcing signaling; handling passive operations such as splitting and filtering.
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 Service 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.
Adaptive Timeout
Retry with exponential timeout: first attempt — 1 sec and the last attempt — 16 secs.
Additional Call Offering (ACO)
An ISDN feature that allows multiple calls to be placed simultaneously to the same telephone number. A serving switch is programmed with the number of lines on the receiving telephone equipment. The switch will offer an additional call if there is a line available to accept it. 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.
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.
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 is not active.
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.
Advanced Television System Committee (ATSC)
An organization founded in 1983 to research and develop a digital TV standard for the U.S.; an international organization of 200 members that is establishing voluntary technical standards for advanced television systems.
Aerial Plant
Cable that is suspended in the air on telephone or electric utility poles.
AGC Threshold
The level of input current at which the AGC circuit becomes active.
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.
An automatic signal-processing strategy that varies the way in which multiple antenna elements are employed as a function of operational scenarios.
A-Links are SS7 links that interconnect STPs and either SSPs or SCPs. "A" stands for "Access."
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.
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 subscribers 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.
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.
A device that converts a signal whose input is information in the analog form and whose output is the same information in digital form.
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.
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.
An application is a functional implementation realized as software running in one or spread over several 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 Platform responsible for managing the lifecycle of the applications. It manages both 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 also 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.
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.
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).
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.
The process of verifying the claimed identity of an entity to another entity.
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.
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 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 Slope Control (ASC)
Circuitry which permits amplifier response compensation for varying slope (tilt) at its input.
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.
B Channel
An ISDN B Bearer channel can be used to carry voice or data connections at speeds of 56 or 64Kbps.
Back Channel
A back channel is a term that applies to asymmetric data connections. It is the slower of the two data paths, or directions, in the connection. Often times, as with ADSL and 56Kbps modems, the back channel is transmitted over the same set of wires or other media as the larger of the two data paths. In other cases, such as with satellite downlinks and some cable modem systems that use a modem and the telephone system to carry the back channel, the data is returned via a different transmission media.
Back Porch
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.
Part of a network used as the primary path for transmitting between network segments. Also, high-speed line or series of connections that forms a major pathway within a network.
Backbone Microwave System
A series of directional microwave paths carrying common information to be relayed between remote points; 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.
Backus Naur Form (BNF)
A formal notation used to define the syntax of a language.
(1) Analog Bandwidth: A measure of spectrum (frequency) use or capacity. For instance, an analog voice transmission by telephone requires a bandwidth of about 3000 hertz (3KHz). A TV channel occupies a bandwidth of 6 million hertz (6MHz) of radio frequency (RF) bandwidth. Cable system bandwidth occupies 50 to 300 MHz on the electromagnetic spectrum. (2) Measure of the frequency width of a transmission channel, or the difference between the highest and lowest frequency levels. Information-carrying capacity of a communication channel. The amount of transmission capacity possessed by a system or a specific location in a system. (3) Digital Bandwidth: The data rate of a digital signal carried in a data transmission channel. Digital bandwidth is commonly stated in units of bits-per-second (bps) and bytes-per-second (Bps) where 8 bits equals one byte. For example, DOCSIS 2.0 is capable of an upstream digital bandwidth of 27 Mbps in an analog channel bandwidth of 6.4 MHz using the 64 quadrature amplitude modulation (64 QAM).
Bandwidth Allocation Map
The DOCSIS MAC Management Message that the cable modem termination system uses to allocate transmission opportunities to cable modems.
Base Station
Also called cell station. A radio transceiver (transmitter/receiver) that uses processing hardware/software and an antenna array to control and relay voice and data signals between the central office of a telephone network, or the internet transport provider, and the remote subscriber unit (fixed or mobile) or internet appliance; it connects wireless users to a phone network, or to an internet service provider.
A transmission scheme that does not employ carrier modulation. In digital baseband systems, data is sent by varying the voltage (pulse amplitude modulation—PAM) or the duration (pulse width modulation—PWM) of signal pulses to indicate different values.
Baseline Privacy Interface (BPI)
A set of extended services within the DOCSIS MAC sublayer. BPI gives subscribers data privacy across the RF network, encrypting traffic flows between the cable modem termination system and cable modem.
Baseline Privacy Interface+ (BPI+)
BPI+ strengthens service protection by adding digital-certificate-based cable modem authentication to its key exchange protocol. BPI+ provides a level of data privacy across the shared medium cable network equal to or better than that provided by dedicated line network access services (analog modems or digital subscriber lines).
Basic Cable
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.
Basic Rate Interface (BRI)
An ISDN BRI is a basic ISDN telephone connection commonly used for small office, home, and ISDN voice telephone service. Each ISDN BRI has two 56 or 64Kbps B Channels and one 16Kbps D Channel.
Baud Rate
The measure of the speed of transmission of a digital code.
In telecommunications lexicon, a binder is a grouping of wires inside a common sheath. The common two-pair telephone cable you can buy at hardware stores for household wiring jobs (black, yellow, green, and red wires) is a two-pair binder. Binders can hold almost any number of wires. Thick telephone company trunk binders may hold 250 pairs. Neighborhood streets generally have 20, 50 or even 100 pair telephone binders supplying "dialtone" to the neighborhood. Within a house, two-pair binders are very common. Modern office building often funnel 4, 6, or 8 pair cables to each desktop to provide telephone and computer network connections.
(1) An abbreviation of binary digit. A bit can be one of the two binary characters, either a 1 or 0. (2) A unit of information. One bit of information is sufficient to specify one of two equally likely possibilities.
Bit Error Rate (BER)
The fraction of bits transmitted that are received incorrectly.
Bit Rate
The rate of a binary-coded transmission which is the number of bits per second.
Bits per Second (b/s)
Digital information rate expressed in the number of binary information units transmitted per second. Typically, a data channel is described as having a stated bit rate and a stated expected error rate.
Blanking (Picture)
The portion of the composite video signal whose instantaneous amplitude makes the vertical and horizontal retrace invisible.
Block Tilt
A method of setting the output levels of all low-band channels at a given number of dB lower than high-band channels.
Telecommunications shorthand for Bandwidth on Demand Interoperability Group. A method for combining two ISDN B Channels into a single logical 128Kbps connections. Used most often for video conferencing and emulating a standard analog modem connection.
A specific marked point in a Web document that allows quick access for returning to that point. When you want to easily return to a Web page, create a bookmark for it. This term is usually used by Netscape; Microsoft Internet Explorer calls these favorites.
Boot Loader
The boot loader is a software component, provided with the host device, which is responsible for loading the entire software stack from the cable operator.
Bound application
Bound applications are those applications which are bound to, or associated with, a particular service made available by the cable operator.
Bridge Protocol Data Unit (BPDU)
Spanning tree protocol "hello packet" sent out at intervals to exchange information among bridges in the network.
Bridged Tap
Wires that are connected to a network, in which one end of the wire is unconnected to proper termination equipment. (ex: A consumer or technician removes devices without completely disconnecting the old device.)
Bridger Amplifier
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. 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.
A transmission medium that allows transmission of voice, data, and video simultaneously at rates of 1.544Mbps or higher. Broadband transmission media generally can carry multiple channels—each at a different frequency or specific time slot.
Broadband Communications System
Frequently used as a synonym for cable television. It can describe any system capable of delivering wide-band channels and services.
Broadband Modulation
The transfer of information by a radio signal requires a certain minimum amount of spectrum space. This minimum depends on the rate at which this information is conveyed. Sometimes called wideband modulation.
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 TV wiring to standard Ethernet LAN connections, which you can plug into a computer's Ethernet network card.
A broadcast is a service that is delivered to all customers. Each customer may select a particular broadcast channel out of many.
Broadcast Addresses
A predefined destination address that denotes the set of all service access points.
Broadcast Application
A broadcast application is an application running on a set-top converter that is loaded through in-band information, inserted either at the headend or by a content provider further upstream.
Broadcast Control Channel
The channel, broadcast continually from the base station, that contains telemetry, identification and configuration data.
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 converters for application use.
Broadcaster's Service Area
Geographical area encompassed by a station's signal.
The dissemination of any form of radio electric communications by means of Hertzian waves intended to be received by the public. Transmission of over-the-air signals for public use.
A device that routes specific protocols, such as TCP/IP and IPX, and bridges other protocols, thereby combining the functions of both routers and bridges.
A program used to graphically display HTML documents from the World Wide Web or other sources. Newer versions of most browsers can also display video clips and animations, play sound and interactive games. The two most popular browsers are Microsoft Internet Explorer and Netscape Communicator.
Burst Error Second
Any errored second containing at least 100 errors.
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.
Business-to-Business (B-to-B)
Used to describe an e-commerce site used to facilitate business between two separate businesses.
Business-to-Consumer (B-to-C)
Used to describe an e-commerce site used to facilitate business between a business and a consumer.
A unit of data measurement made up of eight bits, 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 things such as RAM and hard drive size.
Cable Loss
Defines the amount of cable loss that an amplifier is aligned (pre-equalized) through during factory alignment. Aligning an amplifier through cable creates a tilted gain response.
Cable Modem (CM)
A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system. Cable Modems offer a very high speed connection to the Internet, up to 30Megabits per second (several hundred times the speed of a 56Kbps modem). Technically speaking, though, a cable modem is not a modem at all, but a broadband network bridge.
Cable Modem Termination System (CMTS)
Located at the cable television system headend or distribution hub, a CMTS provides complementary functionality to the cable modems to enable data connectivity to a wide-area network.
Cable Modem Termination System-Network Side Interface (CMTS-NSI)
The interface between a CMTS and the equipment on its network side.
Cable Modem to CPE Interface (CMCI)
The part of the DOCSIS specification defining the communication between the cable modem and consumer premise equipment (CPE) devices.
Cable Network
Refers to the cable television plant that would typically be used for data over cable services. Such plants generally employ 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 share a common communication path for upstream and a separate common path for downstream (i.e., effectively a pair of unidirectional buses).
Cable Powered
Devices obtaining a/c. power simultaneously with RF on the coaxial cable.
Cable Powering
A method of supplying power to solid-state cable television equipment by using the coaxial cable to carry both signal and power simultaneously.
Cable System
Facility that provides cable service in a given geographic area, comprised of one or more headends.
Cable Television Relay Services (CARS)
Terrestrial microwave frequency band used to relay television, FM radio, cablecasting and other signals from the original reception site to the headend terminal for distribution over cable.
Cable Termination
RF frequency signals traveling in coaxial cable will reflect off any impedance that does not match the 75-ohm impedance of the cable. This will cause serious signal distortion. For this reason, the ends of all the trunk and distribution cables are terminated with a 75-ohm load to ground.
Cable TV
A communications system which distributes broadcast programs and original programs and services by means of coaxial cable.
A removable security module (in a PCMCIA or PC card form factor) which, when inserted in an OpenCable certified set-top, television or other device, enables delivery of digital video programming and other services. The OpenCable specification is designed in part to support the retail sale of advanced digital set- top boxes and other devices. CableCARDs will be provided directly by the cable operator to customers who request them. Or a CableCARD is a detachable device, distributed by cable providers, that connects to the home receiver. The interface between the CableCARD unit and the receiver is specified by the OpenCable platform. CableCARD functionality includes copy protection and signal demodulation.
To originate programming over a cable system. Includes public access programming.
A software product developed by TapSCAN which tabulated Nielsen household and demographic data for cable.
Call Agent
In a PacketCable™ 1.0-based network, Call Agent is a synonym for Call Management Server (CMS). The term originates from the Simple Gateway Control Protocol (SGCP) specification. The Call Agent or CMS maintains network intelligence and call state, and controls the media gateway. "Server" is sometimes also used as a synonym for Call Agent or Call Management Server.
Call Appearance
A Call Appearance is an iteration of a telephone Directory Number (DN) that allows multiple concurrent calls to the same phone number. An ISDN line with three call appearances for a single DN, for example, can have three people on the line or on hold to the same number at the same time.
Call Detail Record (CDR)
A data record typically used in a telephony system to record usage information on a per-call basis. Typical fields in the record include originating number, terminating number, start-time, duration, etc.
Call Management Server (CMS)
In a PacketCable™ 1.0-based system, this is the entity that maintains call state and implements features, such as Custom Local Area Signaling Service (CLASS) features. The CMS controls both the in-home media gateways and the media gateways connecting to the Public Switched Telephone Network (PSTN). The CMS also performs admission control and routing functions.
Caller ID
Caller ID is a telephone company feature that notifies a telephone being called of who is (or at least what phone number is) originating the call. On analog POTS phone systems, Caller ID information is transmitted to the telephone set between the first and second ring of the phone. On ISDN sets, Caller ID data is sent as part of the Q9.31 "call setup" information sent of the ISDN D channel. Some states, like California, regulate the implementation of Caller ID very strictly, requiring that phone companies offer their customers the option of keeping their numbers private when placing a call.
Capability Package
ISDN Capability Packages, like Capability Package U, are standardized ISDN feature sets defined by ISDN Order Codes.
A cable system's procedure of carrying the signals of television stations on its various channels. FCC rules determine which signals cable systems must or may carry.
An alternating-current wave of constant frequency, phase and amplitude. By varying (modulating) the frequency, phase or amplitude of a carrier wave, information is transmitted.
Carrier Hum Modulation
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.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
The Ethernet media access method. All network devices contend equally for access to transmit. If a device detects another device's signal while it is transmitting, it aborts transmission and retries after a brief pause.
Carrier-to-Noise Ratio (C/N or CNR)
The square of the ratio of the root mean square (RMS) of the voltage of the digitally-modulated Radio Frequency (RF) carrier to the RMS 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 it is 4 MHz.)
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.
Cascade Depth
The number of amplifiers between the headend and the specific subscriber.
Cascading Style Sheets (CSS)
An extension to HTML to allow styles, e.g. color, font, size to be specified for certain elements of a hypertext document. Style information can be included in-line in the HTML file or in a separate CSS file (which can then be easily shared by multiple HTML files).
A self-contained package of reel-to-reel blank or recorded film, videotape or electronically embossed vinyl tape which is continuous and self-rewinding. Similar to a cartridge, but of slightly different design.
Cause Code
A numerical value that indicates the current status of an ISDN call session and what caused that change in status.
C-band satellite
3.7-4.2 gigahertz (Ghz) frequency band used for distribution of programming by most satellite and cable networks.
ATM layer protocol data unit.
A wireless telephone system where each geographic area (cell) is covered by a base station; users are handed over to other base stations as they move from cell to cell; analog and digital systems exist.
Central Office (CO)
A switching system that connects lines to lines and lines to trunks. The term 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.
A message that, at least, states a name or identifies the Certification Authority (CA), identifies the Subscriber, contains the Subscriber's public key, identifies the Certificate's Validity Period, contains a Certificate serial number, and is digitally signed by the CA that issued the certificate.
Certificate of Compliance
The approval of the FCC that must be obtained before a cable system can carry television broadcast signals.
Certificate Revocation List (CRL)
A list of revoked certificates published by each certificate authority.
Certification Authority (CA)
An entity authorized to issue, manage, revoke, and renew Certificates.
A transmission path between two points. The term channel may refer to a one-way path or, when paths in the two directions of transmission are always associated, to a two-way path. It is usually the smallest subdivision of a transmission system by means of which a single type of communication service is provided, i.e. a voice channel, teletypewriter channel, or data channel.
Channel Capacity
The number of channels available for current or future use on a cable system.
Chrominance Signal
That portion of the NTSC color television signal that contains the color information.
An algorithm that transforms data between plaintext and ciphertext.
A set which must contain both an encryption algorithm and a message authentication algorithm (e.g., a MAC or an HMAC). In general, it may also contain a key-management algorithm, which does not apply in the context of PacketCable.
The (encrypted) message output from a cryptographic algorithm that is in a format that is unintelligible.
Circuit Switched Data (CSD)
A type of telephone connection intended to carry data between two digital devices, such as ISDN digital data adapters and video conferencing systems. ISDN lines have to be provisioned correctly if they need to carry CSD connections.
Circuit Switched Data/Circuit Switched Voice (CSV/CSD)
An ISDN provisioning option that allows for both CSV and CSD telephone connections. Unless used to service an ISDN telephone, most home and business ISDN lines are configured to allow both.
Circuit Switched Network
This network transports information on communication links with a dedicated, end- to-end connection established at one or more switching centers between two connected parties for the length of their call. The public switched telephone network (PSTN) uses circuit switching.
Circuit Switched Voice (CSV)
A type of telephone connection intended to carry information between two analog- type devices, such as telephones, modems, and fax machines. ISDN lines have to be provisioned correctly if they need to carry CSV connections.
A set of criteria used for packet matching according to TCP, UDP, IP, LLC, and/or 802.1P/Q packet fields. A classifier maps each packet to a Service Flow. A Downstream Classifier is used by the CMTS to assign packets to downstream service flows. An Upstream Classifier is used by the CM to assign packets to upstream service flows.
The original (unencrypted) state of a message or data. Also called plaintext.
Commonly used term in PacketCable parlance to signify the customer premises equipment.
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.
Closed Circuit
A system of transmitting TV signals in which the receiving and originating equipment are directly linked by cable, microwave or telephone lines, without broadcasting through the air.
The group of homes passed by a single fiber node.
Grouping together of independent cable systems into a larger, more efficient single system that utilizes some of the same infrastructure.
Coarse Wavelength Division Multiplexing (CWDM)
Coarse wavelength division multiplexing (CWDM) is a method of combining multiple signals on laser beams at various wavelengths for transmission along fiber optic cables, such that the number of channels is fewer than in dense wavelength division multiplexing (DWDM) but more than in standard wavelength division multiplexing (WDM).
Coaxial Cable
Copper or copper-sheathed aluminum wire surrounded by an insulating layer of polyethylene foam, 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.
Code Division Multiple Access (CDMA)
A spread spectrum access technology that assigns a code to each multiple access stream of data bits, transmits the spread data streams, and then, at the receiver, despreads and reassembles the data streams to their original format.
Coder-Decoder (CODEC)
A function or device that performs compression and decompression, typically on voice or video streams.
Codes Exchange (CODEX)
A telecommunications Codex specifies how different binary values sent across the telephone network are translated to a from specific sample voltages. See also Codec.
The result of two network nodes transmitting on the same channel at the same time. The transmitted data is not usable.
Color Burst
In NTSC color, 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.
Color Subcarrier
In NTSC color, the carrier whose modulation sidebands are added to the monochrome signal to convey color information, i.e., 3.6 MHz (3.579545 MHz).
A signal combining network that allows several discrete inputs to be added into a common bandwidth and that has high isolation between inputs. Also may refer to a power combining network.
Combining Network
A passive network that permits the addition of several signals into one combined output with a high degree of isolation between individual inputs. It may be a power or frequency combiner.
Common Carrier
Any point-to-point communications relay service available to the general public at non-discriminatory rates. The carrier cannot control message content (e.g., telephone companies).
Common Path Distortion (CPD)
The interference of return path signaling caused by the forward path.
Communication Satellite
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.
Communication Server
A dedicated, standalone system that manages communications activities for other computers.
Competitive Local Exchange Carrier (CLEC)
An alternative local telephone company that competes against incumbent Local Exchange Carriers (LECs) for local and access business. Also known as a Competitive Access Provider (CAP) or Alternate Local Telephone (ALT) company. Companies that build high-bandwidth fiber-optic networks to compete with the incumbent telephone and cable operators. See also Overbuilder.
Composite Second Order Beat (CSO)
The peak of the average level of distortion products due to second-order non- linearies in cable system equipment.
Composite Triple Beat (CTB)
The peak of the average level of distortion components due to third-order non- linearies in cable system equipment.
Composite Video Signal
The complete video signal. For monochrome, it consists of the picture signal and the blanking and synchronizing signals. For color, additional color synchronizing signals and color picture information are added.
A method for compacting the digital representation of a signal for more efficient transmission or storage.
Compulsory License
Legislation requiring copyright holders to license users of copyrighted material (cable television operators) on a uniform basis and for a stipulated fee.
Conditional Access (CA) and Encryption
Conditional access and encryption is a system that provides selective access to programming to individual customers in exchange for payment.
A way to ensure that information is not disclosed to anyone other then the intended parties. Information is encrypted to provide confidentiality. Also known as privacy.
Connectionless Network
This 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.
Constant Bit Rate (CBR)
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 CBR service.
Content is typically used to refer to audio, video and graphic materials used by an application. Sometimes data and applications are also grouped into this term.
Content Protection/Copy Protection (CP)
Content protection is a mechanism to protect the unauthorized copying of video and audio programming.
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.
Device that is attached between the television set and the cable system that can increase the number of channels available on the TV, enabling it to accommodate the multiplicity of channels offered by cable TV.
A special text file that a Web site stores on your hard drive used to identify you to the Web site the next time you visit. A cookie records your preferences when using a particular site, and can also save the information filled out in online forms. They are used to send browser-specific pages, or pages based on information you have provided to the Web site.
Coordinated Universal Time (UTC)
A reference time standard established by the CCIR (a predecessor of the ITU) and maintained by the Bureau International des Poids et Mesures (BIPM). Formerly Greenwich Mean Time (GMT).
Copy Control Information (CCI)
This information is stored on a CableCARD device and delivered to the host to control the copying of content. It is delivered to the CableCARD from the headend, based on arrangements made between the network operator and the content provider.
CPE Controlled Cable Modem
A cable modem in which a portion of the higher-layer processing is performed by an external device, in particular, by a PC.
Critical Length
Distance along a specific cable to cause worst-case mismatch reflection. A function of frequency-attenuation-velocity of propagation parameters of specific cable types.
Cross Modulation
A form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels.
Cross Ownership
Ownership of two or more kinds of communications outlets by the same individual or business. The 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 U.S.
Noise passed between communications cables or device elements.
The process of recovering the plaintext of a message or the encryption key without access to the key.
Cryptographic Algorithm
An algorithm used to transfer text between plaintext and ciphertext.
Custom Local Area Signaling Services (CLASS)
This term refers to a set of voice telephony services that make use of information about the calling or called numbers. Examples are caller ID, Automatic recall (*69), anonymous call rejection, etc.
Customer Premises Equipment (CPE)
Equipment at the end user's premises; MAY be provided by the end user or the service provider.
Customer Service Representative (CSR)
Customer service representative.
Cutoff Frequency
That frequency beyond which no appreciable energy is transmitted. It may refer to either an upper or lower limit of a frequency band.
Cyclic Redundancy Check (CRC)
An algorithm to detect data corruption.
D Channel
An ISDN Data channel is a data connection between the telephone company's switching equipment and its customer's ISDN equipment. It carries telephone connection information—signals to tell your equipment that a call is coming in and carry dialing and call handling information to the phone company's equipment— and can also be used to carry multiple low-speed data connections using the X.25 packet-switching protocol.
Dark fiber
Unused fiber-optic cable that has been deployed but does not have the proper electronic and optical equipment to carry optical (light) signals. Generally considered to be extra fiber that will support future demand for communications capacity.
Data Communication
The movement of encoded information by means of electrical transmission systems. The transmission of data from one point to another over communication channels.
Data Compression
A technique that saves storage space by eliminating gaps, empty fields, redundancies, or unnecessary data to shorten the length of records or blocks.
Data Link Layer
Layer 2 in the Open System Interconnection (OSI) architecture; the layer that provides services to transfer data over the transmission link between open systems.
Data Over Cable Service Interface Specifications (DOCSIS®)
Specification for transmission of data over a cable network that has been approved by the ITU as an international standard. DOCSIS was developed by CableLabs and a consortium of North American multi-system cable operators.
Decibel (dB)
A unit to measure the relative levels of current, voltage or power. An increase of 3 dB indicates a doubling of power, an increase of 10 dB indicates a 10x increase in power, and an increase of 20 dB indicates a 100x increase in power.
A procedure applied to ciphertext to translate it into plaintext.
Declarative Data Essence (DDE-1)
A standard by SMPTE (Society of Motion Picture and Television Engineers) formalizing ATVEF.
A procedure applied to ciphertext to translate it into plaintext.
Decryption Key
The key in the cryptographic algorithm to translate the ciphertext to plaintext.
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
Distortion resulting from non-uniform speed of transmission of the various frequency components of a signal; i.e., the various frequency components of the signal have different times of travel (delay) between the input and the output of a circuit. Also known as Group Delay Distortion.
Delay Spread
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.
The extraction of the modulation or information from a radio-frequency current.
Breakdown of television viewers by such factors as age, sex, income levels, education and race.
Dense Wavelength Division Multiplexing (DWDM)
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 Coarse Wavelength Division Multiplexing.
An electronic circuit that restores a scrambled video signal to its standard form.
The photodiode in optical receivers.
Data communication established by a circuit-switched connection over a telephone network. Generally associated with less than broadband speeds (56 kbps or less).
Differential Gain
In color TV, 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.
Differential Phase
Variation in phase of the color sub-carrier of a TV signal as the level of the luminance signal is varied from blanking to white.
Differentiated Services (DiffServ, or DS)
A protocol for specifying and controlling network traffic by class so that certain types of traffic get precedence—for example, voice traffic, which requires a relatively uninterrupted flow of data, might get precedence over other kinds of traffic. Differentiated Services is the most advanced method for managing traffic in terms of what is called Class of Service (CoS). Unlike the earlier mechanisms of 802.1p tagging and Type of Service (ToS), Differentiated Services avoids simple priority tagging and depends on more complex policy or rule statements to determine how to forward a given network packet. An analogy is made to travel services, in which a person can choose among different modes of travel—train, bus, airplane—degree of comfort, the number of stops on the route, standby status, the time of day or period of year for the trip, and so forth. For a given set of packet travel rules, a packet is given one of 64 possible forwarding behaviors—known as per hop behaviors (PHBs). A six-bit field, known as the Differentiated Services Code Point (DSCP), in the Internet Protocol (IP) header specifies the per hop behavior for a given flow of packets.
(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) Information that is encoded into bits and bytes, or packets (0s and 1s, computer binary language). Generally perceived to be an advanced communication form offering clearer signals and increased transmission capacity.
Digital Application Software Environment (DASE)
A standard by ATSC addressing interactive television.
Digital Audio Visual Council (DAVIC)
DAVIC is an international consortium working on the development of standards for interactive television.
Digital Certificate
A binding between an entity's public key and one or more attributes relating to its identity, also known as a public key certificate.
Digital Compression
An engineering technique for converting a cable TV 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 Enhanced Cordless Telecommunications (DECT)
A European standard governing panEuropean digital mobile telephony. Specified in DVB MHP as a type of return channel network interface for use in receiving and transmitting IP packets.
Digital Facility
A switching or transmission facility designed specifically to handle digital signals.
Digital Program Insertion (DPI)
The digital splicing of one Moving Pictures Experts Group (MPEG) program (typically a commercial) into another based on digital 'cues' within the MPEG transport stream.
Digital Receiver Interface (DRI)
A CableLabs-specified interface over Internet Protocol (IP) that protects cable operators' "harm-to-service" issues. These issues include ensuring that information like emergency alerts and set-up screens are displayed, that there is sufficient bandwidth to deliver the service, that the content is not altered, etc. It also provides commands to enable communication of information between an OpenCable� unidirectional receiver (OCUR) and a home media server (HMS).
Digital Rights Interface Receiver (DRIR)
A more generic term [than home media server (HMS)] for the device on the downstream side of the DRI. This device receives protected digital content over the digital rights interface (DRI) interface and may store or present it according to license agreements with the cable operator. The home management system (HMS) has digital rights management (DRM) change-out, updating, and other requirements that the DRIR does not have.
Digital Receiver Interface Transceiver (DRIT)
A more generic term [than OpenCable™ unidirectional receiver (OCUR)] for the device on the upstream side of the digital rights interface (DRI). This device receives protected digital content from the cable plant that encodes it with an approved digital rights management (DRM) to distribute it over the digital rights interface (DRI). An OCUR has additional requirements around digital rights management (DRM) change-out, updating, and a few other things that a generic digital rights interface transceiver (DRIT) does not have.
Digital Rights Management (DRM) System
A coding system applied to digital content that manages the usage rights of that content. In order to present the content, the rights specified must be honored by the presenting device. This requirement is usually enforced by attaching the digital rights management (DRM) to encrypted content and protecting the information required to decode the content with keys that can only be obtained by a device authenticated by the DRM.
Digital Set-Top Box
A device which accepts digital encoded television broadcasts and converts them to display on an analog television set.
Digital Signal
A signal that has a limited number of discrete states prior to transmission. This may be contrasted with an analog signal which varies in a continuous manner and may be said to have an infinite number of states.
Digital Signature
A data value generated by a public-key algorithm based on the contents of a block of data and a private key, yielding an individualized cryptographic checksum.
Digital Storage Media-Command and Control (DSM-CC)
A syntax defined in the MPEG-2 standard, part 6, for VCR-like control over a bitstream. Playback commands include Still-Frame, Fast-Forward, Advance, Goto.
Digital Subscriber Line (DSL)
High-speed technology to transfer data over an existing twisted-pair copper telephone line. Asynchronous technology (ADSL) provides data transmission rates up to 7 Mbps in one direction, generally within approximately three miles from a telephone central office. See also HDSL and VDSL.
Digital Subscriber Line Access Multiplexer (DSLAM)
A DSLAM is an xDSL line-interface device located in a telephone company Central Office. One side of a DSLAM connects to customer premises network interface devices (NIDs) over the local loop. The other side interfaces with the PSTN and a wide area (Frame Relay or ATM) network system.
Digital Transmission
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, television-can be converted to digital form.
Digital Transmission Licensing Administration (DTLA)
Licensing authority for DTCP, HDCP and 5C certificates.
Digital Video Broadcasting (DVB)
Digital video broadcasting is a European standard for digital television.
Digital Video Interface (DVI)
A specification created by the Digital Display Working Group (DDWG) to accommodate analog and digital monitors with a single connector. There are three different DVI configurations: DVI-A, designed for analog signals, DVI-D, designed for digital signals, and DVI-I (integrated), designed for both analog and digital signals.
Digital Video Recorder (DVR)
A consumer device which uses a hard disk drive to record television programs. Also provides pause of live television feature. See also PVR.
Digital Video Subcommittee (DVS)
An ANSI-sponsored standardization committee of the SCTE.
Direct Broadcast Satellite (DBS)
Satellite technology that transmits directly to the end user or customer. DBS 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). Also known as direct-to-home (DTH) satellite.
Directional Coupler
A high-quality tapping device providing isolation between tap and output terminals.
Directive Transmission
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.
Directory Number (DN)
The number you dial to reach someone by telephone; a telephone number.
Software controls that allow a Windows program to manage video and sound hardware in a computer. It is usually used for multimedia in games or Web pages running under Windows 95/98 and Windows NT.
Dish Antenna
A high-gain antenna, shaped like a dish, that is used for the transmission and reception of ultra-high-frequency and microwave signals.
Disk Operating System (DOS)
The basic term for software which controls a computer's operation and is loaded from some form of disk, usually a hard drive.
Distant Signal
Broadcast TV signals which originate at a point too far away to be picked up by ordinary home reception equipment; also signals defined by the 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.
The departure, during transmission and amplification, of the received signal wave form from that of the original transmitted wave form.
Distribution Hub
A location in a cable television network which performs the functions of a headend for customers in its immediate area, and which receives some or all of its television program material from a master headend in the same metropolitan or regional area.
Distribution Plant
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
The part of a cable television system used to carry signals from the headend to subscriber's receivers. Often applied, more narrowly, to the part of a cable television system starting at the bridger amplifiers.
A telephone company central office switch manufactured by Northern Telecom that has ISDN and other digital telephony capabilities. See also 5ESS.
DOCSIS Radio Frequency Interface (RFI) Specification
CableLabs radio-frequency interface specifications for high-speed data-over-cable systems.
The first version of the Data Over Cable Service Interface Specification. DOCSIS 1.0 defines requirements for cable modems and cable modem termination systems that enable broadband Internet access.
The second version of the DOCSIS protocol specification. DOCSIS 1.1 includes an enhanced Media Access Control (MAC)-layer that contains quality of service (QoS) traffic management functions as well as cable modem authentication extensions.
The third version of the DOCSIS protocol specification, developed to significantly increase the upstream data carrying capacity and the robustness to noise and interference. DOCSIS 2.0 includes advanced TDMA and S-CDMA physical layer technologies.
Document Object Model (DOM)
An API for parsing a document and providing a view of the document by constructing a "tree" of objects in memory. The Document Object Model is a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page.
Document Type Definition (DTD)
A formal grammar to specify the structure and permissible values of XML documents.
Dolby AC-3
Dolby AC-3 refers to the audio encoding format adopted by the ATSC for its advanced television audio encoding. Also known as Dolby digital.
Domain Name Server (DNS)
A server that relates an Internet domain name (such as www.cablelabs.com) to an IP address.
Domain of an Application
The domain of an Xlet characterizes the space within which the Xlet is able to execute. This includes both the connection where the Xlet is delivered and other connections where an already executing Xlet is allowed to continue executing. An application cannot run outside its domain. The maximum lifetime of an application extends from the moment the user navigates to its domain until the moment that the user navigates away from its domain. In the broadcast case, a connection corresponds to a DVB-service. Broadcast signaling indicates which services can load an application and which services allow an already active application to continue.
Two rapid clicks of the primary (usually left) mouse button, usually performed to launch a program or open a file.
Down Conversion
The heterodyning of an input signal with the output of local oscillator, resulting in an intermediate frequency that is lower than the incoming signal frequency.
Transmission of signals from a satellite to a dish or earth station.
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.
DownloadInfoIndication (DII)
A message that signals the modules that are part of a DSM-CC object carousel.
Flow of signals from the cable system control center through the distribution network to the customer. For communication purposes, associated with transmission (down) to the end-user. Or in cable television, the direction of transmission from the headend to the subscriber.
The cable and hardware from tap to subscriber is called the drop.
Drop Cable
Generally 330 feet or less, of coaxial cable, starting at a tap and continuing on to the subscribers connection. Or coaxial cable that connects to a residence or service location from a directional coupler (tap) on the nearest coaxial feeder cable.
Dual Cable
Two independent distribution systems operating side by side, providing double the channel capacity of a single cable.
Dual Tone Multi Frequency (DTMF)
Telephone "touch" tones. So-called because each keypad button pressed generates a unique combination of two audible tones or frequencies.
In a communications channel, the ability to transmit in both directions.
DVB Network
A DVB-network is a collection of MPEG-2 Transport Stream multiplexes transmitted on a single delivery system. For example, all digital channels on a specific cable system make up a DVB network.
DVB-J refers to the Java platform as defined as part of the DVB-MHP 1.0.1 [9]. For the OCAP 1.0 implementation, DVB-J is part of the execution engine.
DVB-J API refers to one of the Java APIs standardized as part of the DVB-MHP 1.0.1 [9]. For the OCAP 1.0 implementation, the DVB-J APIs are supported in the execution engine.
DVB-J Application
A DVB-J application is a set of DBV-J classes that operate together and need to be signaled as a single instance to the application manager so that it is aware of its existence and can control its lifetime through a lifecycle interface. DVB-J applications as specified by the DVB-MHP 1.0.1 [9] are not directly supported by OCAP 1.0 without modifications pertaining to this specification.
Dynamic Host Configuration Protocol (DHCP)
An Internet protocol used for dynamically assigning network layer (Internet Protocol) addresses to IP hosts.
Dynamic Range
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 utilized without exceeding noise, error rate or other performance limits.
Earth Station
Structure, referred to as a "dish," used for receiving and/ or transmitting those electromagnetic signals coming from or going to a satellite.
The right to use land for a specific purpose, such as laying cable.
Earnings before interest, taxes and amortization. Similar to EBITDA, but is reduced to give effect to periodic depreciation expenses.
Earnings before interest, taxes, depreciation and amortization. Also known as operating cash flow by many cable television operators. A financial and liquidity measure (proxy for cash flow) for companies with significant fixed investment or acquisition expenses that do not generally report positive net earnings.
A wave which 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." Also known as reflection.
An eCM is an embedded Cable Modem, i.e., one that has been enhanced with the features of eDOCSIS� Specification specification.
Education Channel
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.
Educational Television Station (ETV)
A non-commercial television station primarily devoted to educational broadcasting.
Electro-Magnetic Interference
Electro-magnetic (EM) interference is caused when magnetic force lines generated by radio waves, electrical current in other phone lines, and events in outer space, like sun-spots, intersect with a telephone wire, generating a slight variation in the electrical current that we hear as "static." Magnetic interference is the major obstacle to higher modem speeds because they change the very precisely modulated analog signal modems use to transmit and receive data. Today's 28.8 Kbps "V.34" modems, for example, usually have to "fall back" to lower speeds of 21.6 to 24 Kbps due to EM interference.
Electromagnetic Spectrum
A continuous range of frequencies of electromagnetic radiation (i.e., oscillating electrical and magnetic energy which can travel through space). Within the spectrum, waves have some specified common characteristics; the TV broadcast spectrum, for instance, ranges from 45 to 890 MHz. See also Frequency.
Electronic Commerce (E-Commerce)
Used to describe commerce that occurs electronically over the Internet.
Electronic Industries Association (EIA)
A voluntary body of manufacturers which, among other activities, prepares and publishes standards.
Electronic Industry Alliance (EIA)
An industry association accredited by ANSI (American National Standards Institute) to develop standards in the areas of electronic components, consumer electronics, electronic information and telecommunications.
Electronic Key Telephone Service (EKTS)
EKTS features allow a single ISDN SPID or B channel to support multiple directory numbers.
Electronic Program Guide (EPG)
An electronic program guide is an application that displays television program information, including program name, start time, and duration.
Element Management System (EMS)
An element management system (EMS) manages one or more of a specific type of telecommunications network element (NE); it is a second layer of management in the telecommunications management network (TMN) hierarchy.
Elementary Stream (ES)
An elementary stream is a generic term for one of the coded video, coded audio, or other coded bit streams. One elementary stream is carried in a sequence of PES packets with one and only one stream id.
The electronic exchange of messages and files between computers on a network, e-mail is the abbreviated form of electronic mail. An e-mail client is usually integrated with popular browsers.
Embedded Subscriber Media Gateway (E-SMG)
A subscriber media gateway (SMG) with the distinct property that the physical node within the SMG also contains a direct media access control (MAC) layer interface to a DOCSIS access network. The only significant functional difference between an E-SMG and a SMG is that the media signaling and streaming function MAY be capable of directly accessing MAC layer services (traffic management, polling-heartbeats, and authentication functions).
A synonym for, and equivalent with, "Embedded Subscriber Media Gateway."
Emergency Alert System (EAS)
The US federal system for alerting the public to emergencies. EAS is a digital upgrade to the old Emergency Broadcasting System.
A method used to translate plaintext into ciphertext.
A form of encoding transmitted data for security purposes. It normally requires the decryption "key" to decipher the transmission upon receipt. The level of security is dependent on the complexity of the key used. A method used to translate plaintext into ciphertext.
Encryption Key
The key used in a cryptographic algorithm to translate the plaintext to ciphertext.
End User
A human being, organization or telecommunications system that accesses the network in order to communicate via the services provided by the network. Also known as customer.
A Terminal, Gateway, or Multipoint Conference Unit.
Engineering Change Notice (ECN)
The final step in the procedure to change specifications. An ECN is officially considered to be part of the specification that it modifies.
Engineering Change Order (ECO)
The second step in the procedure to change specifications. CableLabs posts ECOs to Web site EC table and ECO page (with indication of ECO Comment Deadline). CableLabs issues ECO announcement to an Announcement mail list and working group mail lists (with indication of ECO Comment Deadline). DOCSIS, CableHome, OpenCable and PacketCable all utilize a similar process.
Engineering Change Request (ECR)
The first step in the procedure to change specifications. CableLabs issues ECR number, posts to Web site EC table and ECR page. CableLabs sends ECR to subject area working group mail list (and author). DOCSIS, CableHome, OpenCable and PacketCable all utilize a similar process.
Enhanced TV Binary Interchange Format (EBIF)
EBIF is an multimedia content format that enables interactive applications on the cable system. The primary purpose of the EBIF content format is to represent an optimized collection of widget and byte code specifications that define one or more multimedia pages, similar to web pages, but specialized for use within an enhanced television or interactive television system. EBIF may be downloaded to tens of millions of digital set tops that already have been deployed, thereby enabling fast to market delivery of interactive services.
Equal Access
The offering of access to local exchange facilities on a non-discriminatory basis.
A means of modifying the frequency and/or phase response of an amplifier or network, thereby resulting in a flat overall response.
Equalized Loss
Any loss in cable television systems caused by coaxial cable; also, insertion loss of components designed to match cable loss characteristics.
Equalizing Pulses
Pulses of one half the width of the horizontal sync pulses which are transmitted at twice the rate of the horizontal sync pulses during the blanking intervals immediately preceding and following the vertical sync pulses. The action of these pulses causes the vertical deflection to start at the same time in each interval, and also serves to keep the horizontal sweep circuits in step during the vertical blanking intervals immediately preceding and following the vertical sync pulse.
Error Rate
A measure of the performance of a digital transmission system. It can be specified as a bit error rate (the probability of error per bit transmitted), as a block error rate (the probability of one or more errors in a specified-length block of bits), or in other forms such as percent error-free seconds.
Errored Second
Any 1-sec interval containing at least one bit error.
The most popular LAN technology in use today. The IEEE standard 802.3 defines the rules for configuring an Ethernet network. It is a 10Mbps, 100Mbps, or 1000 Mbps CSMA/CD baseband network that runs over thin coax, thick coax, twisted pair or fiber optic cable.
European Telecommunications Standard. Prefix for certain ETSI documents.
Enhanced Television. A general term that refers to interactive services and applications provided in conjunction with video programming.
European Norms (EN)
Prefix for certain European Telecommunications Standards Institute (ETSI) documents.
European Telecommunications Standards Institute (ETSI)
The European equivalent of ANSI (American National Standards Institute).
Event Message
A message capturing a single portion of a connection.
Events are asynchronous communication between applications and the OpenCable system on which they are being executed. They provide communication between solution elements. An event may also refer to a unit of programming, such as a movie, an episode of a television show, a newscast or a sports game.
The provision in a commercial television film contract that grants exclusive playback rights for the film or episode to a broadcast station in the market it serves. Under the FCC's rules cable operators cannot carry distant signals which violate local television stations' exclusivity agreements.
Execution Engine (EE)
The portion of the OpenCable Platform which will provide a full programming environment for performing complex logic and arithmetic operations which the Presentation Engine (PE) cannot handle alone. In the EE, which will include Sun's JavaTV programming environment, ITV developers will write interactive applications, in Java, following the OCAP specification. When a cable customer with an OpenCable-compliant set-top box accesses the application through the user interface, the application is transparently downloaded into the box. A Java engine or JAVA Virtual Machine (JVM) resident in the set-top decodes the application downloaded over the network, and runs it. Or the execution engine is a platform- independent interface that permits programmatic content as part of the OpenCable Application Platform.
Extended Subsplit
A frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse path signals come to the headend from 5 to 42 MHz. Forward path signals go from the headend from 50 or 54 MHz to the upper frequency limit.
Extensible Hypertext Mark-up Language (XHTML)
A reformulation of HTML in XML. XHTML is a family of current and future document types and modules that reproduce, subset, and extend HTML 4. XHTML family document types are XML based, and ultimately are designed to work in conjunction with XML-based user agents.
The electronic transmission of pictures, charts, graphs, etc., from one place to another by radio, telegraphy or telephone. With special facsimile equipment, a home television receiver may be able to deliver mail and newspapers by cable.
Factory Alignment
Refers to the bench test alignment conditions with the slope and gain controls (where applicable) are turned to maximum and no pad or equalizer is installed. These specs can be used to verify operation during a bench test.
The reduction in signal intensity of one or several of the components of a radio signal, typically caused by the reflective or refractive effects of multi-path.
The Internet Explorer equivalent of a bookmark, it is a Web site location which has been saved to an organized list for quick access at a later time.
The final piece of hardware (familiar to subscribers) on a drop cable. It is cylindrical with a center pin sticking out, that plugs into the set-top box, cable ready TV or VCR.
Federal Communications Commission (FCC)
The agency that regulates communications services, including cable television, at the federal level. Or a US Federal agency responsible for establishing policies to govern interstate and international communications.
Feeder Cable
Coaxial cables that run along streets within the served area and connects between the individual taps which serve the customer drops.
Feeder Line
Cable distribution lines that connect the main trunk line or cable to the smaller drop cable.
Fiber Distributed Data Interface (FDDI)
A network based on the use of optical fiber to transmit data at a rate of 100Mbps. Or a fiber-based LAN standard.
Fiber Node
A point of interface between a fiber trunk and the coaxial distribution.
Fiber Optics
(1) Very thin and pliable tubes of glass or plastic used to carry wide bands of frequencies. (2) Transmission medium that uses glass or plastic fibers vs. other, copper-based wires to transmit data or voice signals. Fiber-optic cable offers much greater capacity and transmission speeds than traditional mediums.
One half of a complete picture (or frame) interval, containing all of the odd or even scanning lines of the picture.
Field Frequency
The rate at which a complete field is scanned, nominally 60 times a second.
File & Print Sharing
A network component which allows a user to share files or printers on their computer with others on the network.
File Transfer Protocol (FTP)
A method used to exchange files between computers on a network or the Internet using the TCP/IP protocol. It can also be the verb used to describe that transfer ("I need to FTP a file to them").
A circuit that selects the frequency of desired channels. Used in trunk and feeder lines for special cable services such a two-way operation.
Flat Loss
Equal loss at all frequencies, such as caused by attenuators.
Flat Outputs
Operation of a cable television system with equal levels of all TV signals at the output of each amplifier.
Flexible Call Offering (FCO)
Defined by Bellcore as a grouping of three common voice telephone features, call transfer, drop, and hold. Also called the Big Three Feature Set by some companies, FCO is a component of the Easy ISDN1 ordering code.
F-Links are Signaling System Number 7 (SS7) links that directly connect two SS7 end points, such as two signal switching points (SSPs). "F" stands for "Facility Associated."
Flow [DOCSIS Flow]
A unidirectional sequence of packets associated with a Service ID and a QoS. Multiple multimedia streams may be carried in a single DOCSIS Flow. Also known as DOCSIS-QoS "service flow"
Flow [IP flow]
A unidirectional sequence of packets identified by OSI Layer 3 and Layer 4 header information. This information includes source/destination IP addresses, source/destination port numbers, protocol ID. Multiple multimedia streams may be carried in a single IP Flow.
FM Cable System
FM radio signals offered by the cable system (the cable must be connected to the subscriber's FM stereo receiver).
Forward Channel
The direction of radio frequency (RF) signal flow away from the headend toward the end user; equivalent to downstream.
Forward Error Correction (FEC)
FEC enables the receiver to detect and fix errors to packets without the need for the transmitter to retransmit packets.
Forward Traffic
Also known as Downstream or Forward Channel. Signals are transmitted to a subscriber from the headend.
Fractional T-1
A Fractional T-1 is a full-blown, two-pair T-1 data connection that has been fractionalized, or set up so that it offers data throughput only a fraction of standard 1.54Mbps T-1 speeds. Data service companies offer them in a range of speeds (128, 254, 382, 512, and 764Kbps), and they cost less than full T-1. Fractional and full-blown T-1 lines all use the same CSU/DSU line driver equipment. That means that fractional T-1 user can increase or decrease the speed of their data connection to match demand without changing their data communications equipment.
When broad television audiences break into smaller segments due to multiple viewing choices and niche programming that targets particular demographics. Also applies to packets in a transmission as a part of DOCSIS 1.1.
One complete picture consisting of two fields of interlaced scanning lines.
Frame Frequency
The rate at which a complete frame is scanned nominally 30 frames per second.
Frame Loss
The percentage of frames that did not reach the destination.
Frame Set
A frame set consists of one downstream, one upstream and one background frame size.
Frame Size
The size of the frames being generated and sent by the SmartBits Tester (including cyclic redundancy check [CRC]).
A contract between a cable television company and a municipal government authorizing the company to install cable and offer cable television service within the community.
Franchising Authority
Governmental body responsible for awarding franchise, specifying the terms of a franchise, and regulating its operation. While the franchise authority is usually a local city or county body, some areas are regulated exclusively on the state level.
The number of times a complete electromagnetic wave cycle occurs in a fixed unit of time, usually one second. The rate at which a current alternates, measured in Hertz on a telecommunications medium.
Frequency Division Duplex (FDD)
The simultaneous exchange of uplink and downlink information on different frequencies.
Frequency Division Multiple Access (FDMA)
A multiple access technology that separates users by putting each traffic channel on a discrete frequency band.
Frequency Modulation (FM)
A common method of transmitting information over a carrier wave by changing its frequency.
Frequency Response
The change of signal gain and phase with frequency.
Front End
The first radio-frequency amplifier stage on a receiver. This is one of the most critical components of the receiver because the sensitivity of the front end dictates the sensitivity of the entire receiver.
Front Porch
That portion of the composite picture signal which lies between the leading edge of the horizontal blanking pulse, and the leading edge of the corresponding sync pulse.
Full Duplex
Means that communications between two end points can take place at the same time. A standard voice telephone call is a full-duplex call because both parties can talk at the same time and be heard. A short wave radio conversation between two people is not full duplex because the person talking has to press the transmit button to talk, and while he is talking he can not hear the other party. See also Half Duplex.
Full Network Station
A commercial television broadcast station that generally carries 85 percent of the hours of programming offered by one of the three major national networks during its weekly prime time hours.
Full Service Network (FSN)
Cable networks that are intended to provide broadcast TV, Internet access, VOD, and voice telephony simultaneously.
Full-Duplex Transmission
A method of operating a communications circuit so that each end can simultaneously transmit and receive.
Full-Motion Video
Not compressed; a standard video signal of 30 frames per second, 525 horizontal lines per frame, capable of complete action.
Fully Integrated System
A cable television system designed to take advantage of the optimum amplifier- cable relationship for highest performance at lowest cost. Such a system is also admirably suited to the fully automated cable television system concept.
A function is a process which conveys or transforms data in a predictable way. It may be affected by hardware, software or a combination of the two.
A measure of amplification expressed in dB. Gain of an amplifier is usually specified at the highest frequency of operation, for example, at Channel 13 of all- band equipment.
Gain Control
An adjustable control that changes the gain of an amplifier.
Gain Slope
A linear variation in gain from the lowest frequency to the highest frequency.
Gate Controller (GC)
In a PacketCable 1.0-based network, the GC is responsible for authorizing the enhanced quality of service for the media stream.
Gateway (GW)
A function or server that acts as a point of interconnection between two different networks. For example, a Public Switched Telephone Network (PSTN) gateway would interconnect a PacketCable-based network with the PSTN. A computing machine which is both connected to one or more networks and is capable of passing network information from one network to another.
A shadowy or weak image in the received picture offset either to the left or right of the primary image, the result of transmission conditions which create secondary signals that are received earlier or later than the main or primary signal. A ghost displaced to the left of the primary image is designated as "leading" and one displaced to the right is designated as "following" (lagging). When the tonal variations of the ghost are the same as the primary image, it is designated as "positive" and when it is in reverse, it is designated as "negative."
GigaHertz (GHz)
One billion cycles of electrical frequency per second.
Global System for Mobility (GSM)
A digital cellular service designed for world-wide implementation; uses a combination of TDMA and FDMA. Or Global System for Mobile Communications (GSM)—An international standard, developed in Europe, for digital mobile communications.
Global Title Translation (GTT)
Network routing functionality required to offer customers advanced features such as local number portability (LNP), toll-free, calling card, calling name delivery, and roaming support, as well as other advanced network services.
Government Channel
FCC rules require cable systems in the top 100 markets to set aside one channel for local government use, to be available without cost for the "developmental period." That period runs for five years from the time that subscriber service began, or until five years after the completion of the basic trunk line.
Exempting cable systems from the federal rules because 1) they were in existence or operation before the rules, or 2) substantial investments were made in the system construction before the rules. Grandfathering applies to signal carriage, access channels and the certification process.
Ground Communication Equipment
Satellite earth station electronic equipment.
Group Delay
The difference in transmission time between the highest and lowest of several frequencies through a device, circuit or system.
Guard Band
Minimum time allocated between bursts in the upstream referenced from the symbol center of the last symbol of a burst to the symbol center of the first symbol of the following burst. The guard band should be at least the duration of five symbols plus the maximum system timing error.
Guard Time
The term guard time is similar to the guard band, except that it is measured from the end of the last symbol of one burst to the beginning of the first symbol of the preamble of an immediately following burst. Thus, the guard time is equal to the guard band - 1.
An ITU-T standard for transmitting and controlling audio and video information. The H.323 standard requires the use of the H.225/H.245 protocol for communication control between a "gateway" audio/video endpoint and a "gatekeeper" function.
Half Duplex
Two-way transmission, one way at a time.
Most commonly, a dark area surrounding an unusually bright object, caused by overloading of the camera tube. Reflection of studio lights from a piece of jewelry, for example, might cause this effect. With certain camera tube operating adjustments, a white area may surround dark objects.
The equipment involved in production, storage, distribution or reception of electronic signals. In cable television it means the headend, the coaxial cable network, amplifiers, the television receiver and production equipment like cameras and videotape recorders.
Harmonic Distortion
Form of interference involving the generation of harmonics according to the frequency relationship f=nf1 for each frequency present, where n is a whole number equal to 2 or more.
Harmonic Related Carrier (HRC)
A method of spacing television channels on a cable television system in exact 6- MHz increments, with all carrier frequencies harmonically related to a common reference.
Hashed Message Authentication Code (HMAC)
A message authentication algorithm, based on either SHA-1 or MD5.
The control center of a cable television system, where incoming signals are amplified, converted, processed and combined into a common cable along with any original cablecasting, for transmission to subscribers. The system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors and other related equipment. Or the central location on the cable network that is responsible for injecting broadcast video and other signals in the downstream direction. See also Master Headend, Distribution Hub.
Headend Router
The computer, at the cable headend, responsible for gateway operations between the headend and the internet.
Protocol control information located at the beginning of a protocol data unit.
Hertz (Hz)
A unit of frequency equivalent to one cycle per second. See also Megahertz and Gigahertz.
A process of the shifting of a signal of interest down to a frequency at which it may be processed more easily to extract information.
High Band
TV channels 7 through 13.
High Electron Mobility (HEMT)
A transistor that yields the lowest noise figures in single FET devices.
High Frequency (HF)
Used here to refer to the entire subsplit (5-30 MHz) and extended subsplit (5-42 MHz) band used in reverse channel communications over the cable television network.
High Q
A fiber circuit with a great deal of selectivity.
High Return
A frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the headend above the downstream passband.
High Split
When the upstream frequencies are 5-150/174-750 MHz; this split provides the greatest amount of return path.
High VHF Band
Part of the frequency band which the FCC allocates to VHF broadcasting, including channels 7 through 13, or 174 through 216 MHz.
High-bandwidth Digital Content Protection (HDCP)
A specified method from Intel for protecting copyrighted digital entertainment content that uses the Digital Video Interface (DVI) by encrypting its transmission between the video source and the digital display (receiver). The video source might be a computer, set-top box, or DVD player, and the digital display might be an LCD display, television, plasma panel or projector.
High-definition Multimedia Interface (HDMI)
A specification that combines video and audio into a single digital interface for use with DVD players, digital television (DTV) players, set-top boxes, and other audiovisual devices. The basis for HDMI is High Bandwidth Digital Content Protection (HDCP) and the core technology of Digital Visual Interface (DVI). HDCP is an Intel specification used to protect digital content transmitted and received by DVI-compliant displays.
High-definition Television (HDTV)
A television signal with greater detail and fidelity than the current TV systems used. The USA currently uses a system called NTSC. HDTV provides a picture with twice the visual resolution as NTSC as well as CD-quality audio. Or television that substantially exceeds NTSC, PAL or SECAM in resolution and quality.
High-speed Digital Subscriber Line (HDSL)
High-speed digital subscriber line that utilizes existing copper infrastructure of the telephone companies. HDSL offers video and data transmission rates of 1.5 Mbps up to 12,000 feet. See also DSL.
Home Audio/Video Interoperability (HAVi) Architecture
A specification defined by a consumer electronics industry consortium. It is composed of a set of API's allowing for the development of applications for a home networked environment.
Home Media Server (HMS)
A general class of devices designed to receive media content and present it or forward it to another device for presentation. An HMS must use the digital rights interface (DRI) and an approved digital rights management (DRM) in order to get digital content from the cable operator.
Home Page
The default Web page that is displayed when you open your browser. The browser may be configured to automatically load this page on start-up, or not until the home button is pressed. It also refers to the main page of a Web site.
Homes Passed
Total number of homes which have the potential for being hooked up to the cable system.
Horizontal (Hum) Bars
Relatively broad horizontal bars, alternately black and white, which extend over the entire picture. They may be stationary, or may move up or down. Sometimes referred to as a "Venetian blind" effect. Caused by approximate 60-cycle interfering frequency, or one of its harmonic frequencies.
Host Device
A host device refers to the set-top or receiver containing and executing the OpenCable Application Platform implementation. It is also host to the CableCARD device.
House Drop
The coaxial cable that connects each building or home to the nearest feeder line of the cable network.
Device used to connect segments of a network. A hub offers bandwidth on demand to shared resources vs. being fixed to all accessible ports. A signal distribution point for part of an overall system. Larger cable systems are often served by multiple hub sites, with each hub in turn linked to the main headend with a transportation link such as fiber optics, coaxial supertrunk, or microwave. A hardware device that interconnects computers on a Local Area Network and acts as a central distribution point for the communications lines.
Corresponds to "color" in everyday use; i.e., red, blue, etc. Black, white and gray do not have hue.
Hum Modulation
Undesired modulation of the television visual carrier by the fundamental or low- order harmonics of the power supply frequency, or other low-frequency disturbances.
Hybrid Fiber/Coax(ial [cable]) (HFC)
HFC system is a broadband bi-directional shared media transmission system using fiber trunks between the headend and the fiber nodes, and coaxial distribution from the fiber nodes to the customer locations.
HyperText Markup Language (HTML)
The language used to create and display Web documents. It uses "tags" to identify the components of a document (text, graphics, multimedia) and how those components should behave.
HyperText Transfer Protocol (HTTP)
The standard for exchanging files (text, graphics, and multimedia) on the World Wide Web. Or HTTP is the transport layer for HTML documents over the Internet Protocol (IP).
HyperText Transfer Protocol Secure (HTTPS)
An extension of HTTP developed by Netscape to enable security on a Web site. HTTPS encrypts and decrypts your page requests and the data returned to you by a Web server.
An electronics standard for connecting devices to a personal computer or set-top box. IEEE-1394 provides a single plug-and-socket connection on which up to 63 devices can be attached with data transfer speeds up to 400 Mbps (megabits per second). The standard describes a serial bus or pathway between one or more peripheral devices and a host's microprocessor. Also known as Firewire or i.Link.
Resistance to alternating-current flow.
Impulse Noise
Short bursts of high-level noise such as that resulting from the coupling of transients into a channel. Typical sources of such noises are lightning and transients from switching systems. Impulse noise, which sounds like a click, is not particularly detrimental to voice communications, but it can be detrimental to data communications. Or noise characterized by non-overlapping transient disturbances.
Impulse-Pay-Per-View (IPPV)
A service that allows a user to order and receive pay-per-view content in near real-time. Current pay-per-view models require that the user make arrangements to purchase the content prior to its reception.
Incremental Related Carriers (IRC)
A method of spacing National Television Systems Committee (NTSC) television channels on a cable television system in which all channels except 5 and 6 correspond to the standard channel plan, used to reduce composite triple beat distortions.
Incumbent Local Exchange Carrier (ILEC)
This term refers to traditional local telephone companies such as one of the Regional Bell Operating Companies (RBOCs) in the United States.
A TV station that has no exclusive affiliation which obliges it to carry programs from one of the national networks. Individually-owned and operated cable television system, not affiliated with a Multiple System Operator.
Independent Operator
Individually owned and operated cable television system, not affiliated with an MSO.
The ability of a device to store energy in the form of a magnetic field.
An electronic component designed to provide a controlled amount of inductance.
Industry Standard Architecture (ISA)
An interface standard for connecting hardware expansion cards to a computer. The typical ISA connection is a slot, or edge-card connector, on the computer's motherboard allowing devices such as sound cards and telephone modems to be plugged in to the computer.
A commercial, usually 90 seconds or more in length, designed to supply information about a product or service rather than to present a specific sales message.
Inline Package
A housing, for amplifiers or other cable television components, designed for use without jumper cables; cable connectors on the ends of the housing are in line with the coaxial cable.
Insertion Loss (IL)
Additional loss in a system when a device such as a directional coupler is inserted; equal to the difference in signal level between input and output of such a device.
Institute of Electrical and Electronics Engineers (IEEE)
A voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute (ANSI). For more information, refer to www.ieee.org.
Institutional Network
A network that is operated in conjunction with a cable TV system and which is designed to satisfy the needs of schools, businesses, or government.
Integrated Services Digital Network (ISDN)
ISDN is a digital telephone line that can be used for voice, fax, and data communications like a regular telephone line, but can transport data five times faster (or more) than a 28.8Kbps V.34 modem and allow you to talk on the phone to one person while sending data to another.
Integrated Services Digital Network User Part (ISUP)
ISUP is a protocol within the Signaling System Number 7 (SS7) suite of protocols that is used for call signaling within an SS7 network.
A way to ensure that information is not modified except by those who are authorized to do so.
Interactive Cable
Cable systems that have the technical ability to let subscribers communicate directly from their television sets with a computer at the system headend using special converters and regular cable lines. Viewers are able to order movies and video games, access library information, and request sales brochures and coupons from home.
Interactive Program Guide (IPG)
A guide similar to an EPG, but with increased interactive features, such as allowing users to sort through onscreen TV listings by time, or channel, or themes, like children's shows, and program a VCR or TV directly from within the guide.
Interactive Television (ITV)
A combination of television with interactive content and enhancements. ITV provides a richer entertainment experience as well as information, blending traditional TV viewing with the interactivity of a PC. ITV features can include richer graphics, Internet access, e-mail, chat, instant messaging, home shopping, home banking, interactive games, on-demand services such as weather and financial information, pay-per-view (PPV), and video-on-demand (VOD). Or a catch all phrase for services/platforms that allow TV viewers to interact with their television. Typical services might include interactive program guides and e-mail and web browsing on the TV.
Interactive Voice Response System (IVR)
The automated telephony systems we are all familiar with that direct our calls within a company or organization, e.g., "Please press one for customer service, press two for technical support, press zero for the operator."
The ability to exchange tapes between different manufacturers' videotape recorders with no appreciable degradation of playback image.
Two or more cable systems distributing a programming or commercial signal simultaneously.
A method of receiving TV signals by jamming unauthorized signals but having all other signals received in the clear. Because the jamming is accomplished outside the home it does not require a set-top terminal in the home.
Inter-exchange Carrier (IC)
A communications common carrier that provides telecommunications services between Local Access and Transport Areas (LATA) or between exchanges within the same LATA.
Inter-Exchange Carrier (IEC)
A long distance phone carrier, like AT&T, MCI, or Sprint.
Energy which tends to interfere with the reception of the desired signals, such as fading from airline flights, RF interference from adjacent channels, or "ghosting" from reflecting objects such as mountains and buildings.
Interference Rejection
Reception of unwanted signals is interference; smart antenna systems reject interference by nulling the unwanted signal through phase shifting; they also reduce interference to other systems by nulling the transmitted signal in the direction of the unintended receiver.
Interlaced Scanning (Interlace)
A scanning process in which each adjacent line belongs to the alternate field.
The television display format, where horizontal lines of pixels are illuminated in an alternating pattern rather than sequentially.
Inter-Local Access and Transport Area (InterLATA)
This term refers to services provided across local access and transport areas (LATAs), roughly corresponding to the concept of long-distance communication. The 1984 breakup of AT&T opened up competition for interstate calls, and most states soon allowed competition for calls between LATAs within their states. Regional Bell operating companies (RBOCs) currently are prohibited from providing inter-LATA service until they meet certain requirements related to opening their networks to competitors as detailed in the Telecommunications Act of 1996.
In a receiver, an unwanted signal sometimes interacts with the desired signal. The desired signal appears to be modulated by the undesired signal.
Intermodulation Distortion
Form of interference involving the generation of interfering beats between two or more carriers according to the frequency relationship f=nf1+/- mf2, where n and m are whole numbers (but not zero), with appropriate expansion for additional carriers.
International Electrotechnical Commission (IEC)
An international standards body.
International Organization for Standardization (ISO)
An international standards body, commonly known as the International Standards Organization.
International Telecommunications Union (ITU)
A United Nations organization that establishes standards for telecommunications devices, like ISDN hardware, modems, and Fax machines. ITU standards include J.112, J.122, H.323, V.90, X.25, and X.500.
A series of interconnected local, regional, national and international networks, linked using the Internet Protocol. The Internet is accessible via telephony wires, HFC networks and by satellite.
Internet Assigned Numbered Authority (IANA)
The entity responsible for assigning numbers in the Internet Suite of Protocols.
Internet Control Message Protocol (ICMP)
An internet network layer protocol.
Internet Engineering Task Force (IETF)
A body responsible for, among other things, developing standards used in the Internet. Or a cooperative consortium that standardizes internet protocols, naming and other communications issues.
Internet Group Management Protocol (IGMP)
A network-layer protocol for managing multicast groups on the Internet.
Internet Key Exchange (IKE)
A method standardized by the IETF for exchanging security keys.
Internet Protocol (IP)
The computer network protocol (analogous to written and verbal languages) that all machines on the Internet must know so that they can communicate with one another. IP is a layer 3 (network layer) protocol in the OSI model. The vast majority of IP devices today support IP version 4 (Ipv4) defined in RFC-791, although support for IP version 6 (Ipv6, RFC-2460) is increasing.
Internet Protocol Security (IPsec)
A collection of Internet standards for protecting IP packets with encryption and authentication.
Internet Service Provider (ISP)
A company that sells Internet access.
Internet Signaling Transport Protocol (ISTP)
A PacketCable protocol used by PacketCable PSTN Signaling Gateways.
Interval Usage Code
A field in MAPs and UCDs to link burst profiles to grants.
Intra-Local Access and Transport Area (IntraLATA)
In the U.S., this term refers to providing services within a local access and transport area (LATA). Regional Bell operating companies (RBOCs) are permitted only to provide intraLATA service; most states allow other carriers to compete with RBOCs within LATAs.
IP Address
A number that uniquely identifies a computer on the Internet to other host computers, used to route data packets to their intended destination. IP version 4 addresses are 32-bits in length and are displayed as four numbers (each in the range 0-255) separated by dots (e.g., 184.108.40.206). In contrast, IP version 6 addresses are 128-bits in length and can be displayed as eight hexadecimal numbers (in the range 0-FFFF) separated by colons (e.g. FEDC:BA98:7654:3210:FEDC:BA98:7654:3210).
A WindowsNT command prompt utility that displays the computer's TCP/IP configuration. It also allows a computer user to manually release and renew their IP address lease.
Integrated systems digital network. Technology that offers digital transmission rates up to 128 kbps over an existing twisted pair copper telephone line.
ISDN Adapter
A piece of telephone equipment that connects directly to an ISDN line or the S/T Interface of an NT-1.
ISDN Digital Subscriber Line (IDSL)
IDSL is a 128Kbps standard proposed by the Ascend Corporation for providing low-cost, dedicated 128Kbps data service using telephone lines and central office switch facility space leased from the telephone company. It uses standard Point-to- Point ISDN signaling techniques to link the customer to the central office headend. See also xDSL.
ISDN Network Terminator, Type 1 (NT-1)
The NT-1 is the dividing line and bridge between the telephone company's ISDN connection ends and the customer's ISDN connection begins. On the telephone company's side of the connection is the two-wire U Interface, on the customer's side of the connection is the eight wire S/T Interface, which connects to the customer's ISDN adapter(s). Most consumer market ISDN adapters sold in North America come with a built-in NT-1, but in Europe and Japan the NT-1 is provided by the phone company, and the ISDN customer has to have equipment that will plug into an S/T bus connection. An external NT-1 can have its advantages. The ISDN S/T interface can support multiple ISDN adapters, as long as each adapter has an S/T Interface and its own SPID.
ISDN User Part (ISUP)
A protocol within the SS7 suite of protocols that is used for call signaling within an SS7 network.
Java API
The Java API is a standard interface for use by platform-independent application software. It is expressed in the Java language.
Java Development Kit (JDK)
A set of resources, including software and documents, provided by Sun Microsystems to enable developers to program in the Java language.
Java Media Framework (JMF)
A Java package providing functionality primarily for data streaming.
Java Secure Socket Extension (JSSE)
A Java package providing functionality for secure network communications.
The variance in latency. Or variability in the delay of a stream of incoming packets making up a flow such as a voice communication.
JPEG File Interchange Format (JFIF)
A platform-agnostic JPEG file format.
Jumper Cable
Short length of flexible coaxial cable used in older cable television systems to connect system coaxial cable to amplifiers or other cable television components.
33 to 36 GHz (gigahertz) frequency band used by satellites. Orbital location of two- way satellite data services provided by DBS companies.
A secret-key network authentication protocol that uses a choice of cryptographic algorithms for encryption and a centralized key database for authentication.
Key Distribution Center (KDC)
A network service that supplies tickets and temporary session keys.
Key Exchange
The swapping of public keys between entities to be used to encrypt communication between the entities.
Key Handling Epoch
The time interval within the application processing that starts with the delivery of a user interface (UI) event to the application and ends with the notification to the platform that the application has completed all actions that may either cause the platform to forward that same key to another application, or influence how the platform will handle the subsequent key. In the case of the execution engine, this notification consists of returning from a key handling callback.
Key Management
The process of distributing shared symmetric keys needed to run a security protocol.
Key Pair
An associated public and private key where the correspondence between the two are mathematically related, but it is computationally infeasible to derive the private key from the public key.
Keying Material
A set of cryptographic keys and their associated parameters, normally associated with a particular run of a security protocol.
Keys are numeric assignments for the various calling features an ISDN adapter supports, like call drop, transfer and hold. Also called buttons, keys get their names from the various feature buttons on an advanced multi-line voice phone. Or a mathematical value input into the selected cryptographic algorithm.
The range of all possible values of the key for a particular cryptographic algorithm.
Kilo (K)
Meaning one thousand. Communications and computer terminology, however, uses the term K or Kilo differently. In communications terminology, one K is equal to 1000, but when measuring computer memory or disk space, one K is equal to 1024.
KiloBits Per Second (Kbps)
One Kbps is equal to 1000 bits transmitted in one second.
Kinescope Recording
A film recording made by a motion picture camera designed to photograph a television program directly from the front of a television tube. Often called a "kine."
The group of microwave frequencies from 12 to 18 GHz; the band of satellite downlink frequencies from 11.7 to 12.2 GHz.
A device that generates coherent electromagnetic radiation in, or near, the visible part of the spectrum.
Last Mile
Refers to the last "mile" between a central office and a customer in a telephone network or a node and a customer in a cable television network. Last-mile distances generally range from 0 miles to 3 miles.
Last Mile Framing
The data encapsulation and transmission protocols used between the consumer premises and the headend. Framing techniques include ATM, MPEG and IP.
The time taken for a signal element to pass through a device or system.
In networks, layers refer to software protocol levels comprising the architecture, with each layer performing functions for the layers above it. Or a subdivision of the Open System Interconnection (OSI) architecture, constituted by subsystems of the same rank.
Cable television operators' practice of skipping over one or more of the nearest TV stations to bring in a further signal for more program diversity. FCC rules establish priority for carrying stations that lie outside the cable systems service area.
The practice by telephone companies of installing and maintaining cable television distribution systems, and leasing the facilities back to separate contractors for operation of the system.
Leased Access
On some systems, a public access channel for which programmers pay a fee for use and are permitted to sell commercial time in their programming. Also known as Leased Channel.
Level Diagram
A graphic diagram indicating the signal level at any point in the system.
Lifetime of an Application
The lifetime of an application characterizes the time from which the application is loaded to the time the application is destroyed.
Line Extender
Types of amplifiers used in the feeder system. Also known as Distribution Amplifier.
Line Frequency
The number of horizontal scans per second, nominally 15,750 times per second.
Line Information Database (LIDB)
Contains information on customers required for real-time access such as calling card personal identification numbers (PIN) for real-time validation.
Line or Loop
An analog or digital access connection from a user terminal which carries user media content and telephony access signaling (DP, DTMF, BRI, proprietary business set).
Line Speed
The rate at which individual bits are transmitted on a telephone connection. A modem's line speed may be set at 14,400 bits per second, an ISDN line at 64,000 bits per second. Line speed does not take into account whether the data it is sending has been compressed to increase actual throughput.
Link Encryption
Cryptography applied to data as it travels on data links between the network devices.
Local Access and Transport Area (LATA)
A geographical area used for regulatory, pricing, and network organization purposes to partition the public switched telephone network into distinct regions. Or a geographical area designated by the telephone company. Frequently, but not always, corresponds to an area code.
Local Access and Transport Area Switching Systems Generic Requirements (LSSGR)
A very large set of documents published by Telcordia (formerly Bellcore) that describes the local telephone network.
Local Area Network (LAN)
A LAN is a collection of computing equipment at a single location (e.g., an office building or campus) that communicate with each other to share resources and information, such as disk storage and files, printers, and e-mail. See also WAN. Or a non-public data network in which serial transmission is used for direct data communication among data stations located on the user's premises.
Local Distribution System (LDS)
A wide band microwave system or cable system which is capable of transporting a number of television signals simultaneously. Used to interconnect cable system headends.
Local Exchange
An exchange where telephone subscriber lines connect.
Local Exchange Carrier (LEC)
Telephone company lingo for your local telephone company. See also RBOC.
Local Loop
This portion of the telecommunications network physically connects end users to the central office network facilities and generally is dedicated to that particular user. Twisted pairs of copper wire form the traditional medium of the telephone network local loop, although other connections now are used in some cases.
Local Multipoint Distribution System (LMDS)
A fixed wireless technology that is one solution for bringing high-bandwidth services to homes and offices within the "last mile" of connectivity.
Local Number Portability (LNP)
A system that allows local telephone numbers to be transferred to competitive local exchange carriers. This allows the subscriber to change local phone companies without experiencing a change in phone numbers.
Local Origination
Programming developed by an individual cable TV system specifically for the community it serves.
Local Signals
Television signals that are received at locations that are within the station's Predicted Grade B Contour. Cable systems must carry all commercial local signals in their areas.
This term has different definitions depending on the application format: A DVB- HTML locator is a link, expressed in the syntax in IETF RFC 2396 [40], which provides an unambiguous pointer to a DVB-HTML document accessible to the MHP in a specific transport stream. The scheme specified should resolve to one of the available transports signaled for the DVB-HTML application. For signed DVB-HTML applications, the schemes HTTP and HTTPS may use the return channel. This version of the specification does not include a scheme for transporting independent locators; future versions are expected to do so. This term in the DVB-HTML context should not be confused with the DVB-J class of the same name.
Logical Link Control (LLC)
The LLC network protocol sublayer is the part of the data link layer that uses the services of the Medium Access Control (MAC) Layer to provide services to the Network Layer. See also Logical Link Control Procedure.
Logical Link Control Procedure
In a local area network (LAN), or a metropolitan area network (MAN), that part of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared.
Long-Distance Service
This term refers to a communication terminating outside the local telephone service area of the originating party. Since 1984 in the U.S., the term generally has meant service across local access and transport areas (LATAs).
Low Band
TV channels 2 through 6.
Low Noise Amplifier (LNA)
A low noise signal booster used to amplify the weak signals received on a satellite antenna. Usually found in the receiver front ends.
Low Pass Filter (LPF)
Replaces the regular filter (used for one-way transmission) on a drop, and enables a subscriber to have 2-way service. The LPF allows low frequencies to pass, but blocks out higher frequencies.
Low Power Television
Broadcast medium that is similar to commercial TV but limited in broadcast coverage area by its low power signal.
Low Split
When upstream frequencies are assigned below 54MHz.
Low VHF Band
The part of the frequency band allocated by the FCC for VHF broadcast television, including television channels 2 through 6, or 54 through 108 MHz.
Luminance Signal
That portion of the NTSC color television signal which contains the luminance or brightness information.
Mail Server
A computer responsible for processing and/or storing e-mail. It is the electronic equivalent of a post office. E-mail accounts exist on a mail server, where e-mail messages are stored until retrieval by the e-mail client.
Main Trunk
The major link from the headend to feeder lines.
Management Information Base (MIB)
An SNMP-defined data structure used for storing and retrieving information to and from network elements.
Mandatory Ordinary Keycodes
The Mandatory Ordinary Keycodes are guaranteed to always be available to the application that has focus. The set of mandatory keycodes includes keycodes required by the MHP specification in the minimum platform capabilities section as the minimum set of input events.
Man-Machine Interface (MMI)
Another term for User Interface.
Master Antenna Television (MATV)
Antenna and distribution system which serves multiple dwelling complexes such as hotels, motels and apartments.
Master Headend
A headend that collects television program material from various sources by satellite, microwave, fiber, and other means, and distributes this material to Distribution Hubs in the same metropolitan or regional area. A master headend MAY also perform the functions of a distribution hub for customers in its own immediate area.
Mean Time to Repair (MTTR)
In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored.
Media Access Control Address (MAC-Address)
The unique hardware number assigned to network connection devices such as your computer's network card. In Ethernet, it is written as a series of six pairs of characters divided by hyphens (e.g., 00-0F-3D-50-A1-98), and is also referred to as the hardware address or adapter address. Or the "built-in" hardware address of a device connected to a shared medium.
Media Access Control or Medium Access Control (MAC)
The MAC sublayer is the part of the data link layer that supports topology- dependent functions and uses the services of the Physical Layer to provide services to the Logical Link Control (LLC) sublayer. Or a component of a networking software stack. In the OSI 7-layer model, the Media Access Control is a part of layer 2, the data link layer.
Media Access Control Procedure (MAC-Procedure)
In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the data exchange between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium.
Media Access Control Service Access Point (MSAP)
The conceptual binding of a media access control (MAC) layer service provider to the protocol entities (i.e., data link layers) above it.
Media Access Control Sublayer (MAC-Sublayer)
The part of the datalink layer that supports topology dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer.
Media Center Edition (MCE)
Microsoft's operating system optimized for the presentation and distribution of digital media content (video, audio, images, etc.).
Media Center Extender (MCX)
Microsoft's satellite media presentation device. Any device licensed by Microsoft to connect to a media center edition (MCE) to obtain and present Windows Media Digital Rights Management (WMDRM) protected digital media content.
Media Gateway (MG)
A MG terminates switched circuit network (SCN) facilities (trunks, loops), packetizes the media stream, if it is not already packetized, and delivers packetized traffic to the packet network. It performs these functions in the reverse order for media streams flowing from the packet network to the SCN.
Media Gateway Control Protocol (MGCP)
Protocol follow-on to SGCP. Refer to IETF RFC 2705.
Media Gateway Controller (MGC)
An MGC is the overall controller function of the public switched telephone network (PSTN) gateway. It receives and mediates call-signaling information between the PacketCable™ and the PSTN domains, and it maintains and controls the overall call state for all calls.
MegaHertz (MHz)
One million cycles per second.
Message Authentication Code (MAC)
A fixed-length data item that is sent together with a message to ensure integrity, also known as a MIC.
Message Digest 5 (MD5)
A one-way hash algorithm that maps variable length plaintext into fixed-length (16 byte) ciphertext.
Message Integrity Check
A fixed-length data item that is sent together with a message to ensure integrity.
Message Transfer Agent (MTA)
A program responsible for receiving incoming messages and routing the messages to individual users.
Message Transfer Part (MTP)
The MTP is a set of two protocols (MTP 2, 3) within the signaling system number 7 (SS7) suite of protocols that are used to implement physical, data link, and network level transport facilities within an SS7 network.
MHP (Multimedia Home Platform) Connected Resource
An MHP connected resource is a resource used as part of the MHP which, on its own, does not conform to the specification but which is connected to an MHP terminal in such a way that the whole is part of the MHP.
MHP (Multimedia Home Platform) Solution
The MHP solution encompasses the whole set of technologies necessary to implement the MHP including protocols and APIs.
MHP (Multimedia Home Platform) Terminal
An MHP terminal is a single piece of physical equipment conforming to the MHP specification, in particular in that it contains a Virtual Machine and an instance of the MHP API.
Echoes in the forward or reverse transmission path due to impedance mismatches between the physical plant components. Micro-reflections are distinguished from discrete echoes by having a time difference (between the main signal and the echo) on the order of 1 microsecond. Micro-reflections cause departures from ideal amplitude and phase characteristics for the transmission channel. These problems can be corrected by equalization.
One millionth of a second.
Microsoft Networking
The Microsoft standard for interconnecting Windows-based PCs on a LAN which uses the Client for Microsoft Networks.
Microwave Oscillator
A device used to generate a microwave signal. It consists of two parts: a resonator to control the frequency of the microwave signal and an active device to generate the power.
High frequency radio waves used for telecommunications transmission. Line-of- sight, point-to-point transmission of signals at high frequency, usually above 890 MHz. Many cable television systems receive some television signals from a distant antenna location with the antenna and the system connected by microwave relay. Microwave frequencies require direct line-of-sight to operate. Trees and buildings distort or block the signal.
Mid Band
The part of the frequency band that lies between television channels 6 and 7, reserved by the FCC for air, maritime and land mobile units, FM radio and aeronautical and maritime navigation. Mid-band frequencies, 108 to 174 MHz, also can be used to provide additional channels on cable television systems.
Mid Split
A frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the headend from 5 to 108 MHz. Forward path signals go from the headend from 162 MHz to the upper frequency limit. The duplex crossover band is located from 108 to 162 MHz.
Miles of Plant
The number of cable plant miles laid or strung by a cable system.
A mini-slot is an integer multiple of 6.25-microsecond increments.
A non-linear circuit that produces an output at the sum and difference frequencies of an applied fixed or variable oscillator called the LO, and the FR input signal of interest.
The path a photon takes in going from one end of an optical fiber to another.
A data communications device. Modem is a combination of two words, modulate and demodulate. Strictly speaking, a modem is a device that accepts a digital signal, then converts or modulates it into an analog signal that another modem can convert back, or demodulate into digital form again. A modem's speed and dependability are adversely affected by electro-magnetic interference, or static.
When some characteristics of an electromagnetic wave are deliberately changed or manipulated for the purpose of transmitting information. Process by which signals are transformed to represent information (or data). Generally uses different frequencies to transmit data (FM). See also QAM.
The electronic equipment required to combine video and audio signals from a studio and convert them to radio frequencies (RF) for distribution on a cable system. Also, a very low-powered television signal generator used to provide signals for distribution on a cable television system.
Monitor Application (MA)
The monitor application is a special unbound application with access to a privileged API set that manages the execution of all applications in the receiver.
Monitor Plus
A spot monitoring service provided by Nielsen which records both local broadcasts and national cable commercial activities.
All photons take the same path down the center of the core of an optical fiber. Also Single-mode Fiber.
A hardware pointing device used to control the movement of an on-screen cursor. The mouse buttons are then used to select items on the screen.
Moving Picture Experts Group (MPEG)
A voluntary body, which develops standards for digital, compressed moving pictures and associated audio.
Video compression standard that requires a minimum of 30 frames per second with CD-quality sound (i.e., 16-bit stereo).
An improved video compression standard over MPEG-1 that offers better resolution at the same 30 frames per second (as MPEG-1). Commonly used by cable television operators and direct broadcast satellite providers to offer digital video services because of its efficient use of capacity, improved quality over analog and stereo sound.
A multicast is a message that is sent out to multiple devices on the network by a host.
Multi-Channel/Multi-Point Distribution (MMDS)
Private service utilizing a very high frequency (2 GHz) to transmit multiple television signals (also called wireless cable).
Multimedia Home Platform (MHP)
The Multimedia Home Platform consists of an MHP viewer terminal, including all possible low-to-high functionality implementations, its associated peripherals, and the in-home digital network.
Multimedia Terminal Adapter (MTA)
The device in a PacketCable network that connects the subscriber equipment (such as a telephone) to the network.
When a photon careens off the optical fiber wall as it goes from one end to the other. Other photons take different paths. There are approximately 200 different paths in a single fiber.
Copies of the desired signal that have arrived at the antenna after bouncing from objects between the signal source and the antenna; these signals can either cancel or reinforce each other.
Multiple (cable) Systems Operator (MSO)
A company that operates multiple cable systems.
Multiple Dwelling Units (MDU)
Apartment buildings and condominiums.
A device that allows several users to share a single circuit. It funnels different data streams into a single stream. At the other end of the communications link, another multiplexer reverses the process by splitting the data stream back into the original streams.
The potential transmission of several feeds of the same cable network with the same programming available at different times of the day. This is seen as one possible use of the additional channel capacity that may be made available by digital compression. Multiplexing is also used by some cable networks to mean transmitting several slightly different versions of the network, for example several MTV channels carrying different genres of music.
Multipoint Access
User access in which more than one piece of terminal equipment is supported by a single network termination.
Multipoint Conferencing Unit (MCU)
A switching device that interconnects H.323- and T.120-compliant conferencing systems in a multipoint conference.
Multipoint Connection
A connection among more than two data network terminations.
Multipoint Controller (MC)
The H.323 entity that provides control of three or more endpoints in a multipoint conference.
Multipoint Microware Distribution System (MMDS)
A wireless broadband technology for Internet access.
Multipoint Mixing Controller (MMC)
A conferencing device for mixing media streams of multiple connections.
Multipurpose Internet Mail Extensions (MIME)
A specification for formatting non-ASCII data for transport over the Internet.
The FCC rule requiring cable systems to carry all local broadcast television signals in their market.
A formula which refers to the FCC requirements that provide for expansion of channel capacity for non-broadcast use. If the governmental, educational, public access, and leased channels are in use 80 percent of the weekdays (Monday through Friday) for 80 percent of the time during any three-hour period for six consecutive weeks, the system operator must expand the system's channel capacity within six months.
This medium is capable of carrying voice, fax, paging, and relatively slow-speed data (not full video applications), typically at 64Kbps or less.
Delivery of programming that addresses a specific need or highly focused audience.
National Cable Telecommunications Association (NCTA)
The trade association for the cable telecommunications industry in the US. Or a voluntary association of cable television operators which, among other things, provides guidance on measurements and objectives for cable television systems in the USA.
National ISDN-1
The North American standard specification for ISDN service.
National Television Systems Committee (NTSC)
Committee, that defined the analog, color television, broadcast standard used today in North America. The standard TV format for North American television transmission is named after this standards committee; the format is 525 lines in a 4-MHz video bandwidth. All TV sets sold in North America are compatible.
Native Application
A native application is an application written in or compiled to the machine code for the particular processor of the OCAP 1.0 device. Typically, it is written in C, C++, or assembly language and may be supplied with the OCAP implementation or downloaded over the cable.
Native Library
A native library is a library written in or compiled to the machine code for a particular processor. Typically, it is written in C, C++ or assembly language.
A navigator is a resident application, typically provided by the manufacturer, that the end user can activate at any time. The navigator can be used to select services, applications, and initiate interoperable applications.
Near-Video-on-Demand (NVOD)
An entertainment and information service that broadcasts a common set of programs to customers on a scheduled basis. At least initially, NVOD services are expected to focus on delivery of movies and other video entertainment. NVOD typically features a schedule of popular movies and events offered on a staggered- start basis (every 15 to 30 minutes, for example). See also Video-on-Demand. Or video-on-demand with which the user may experience some delay before content begins.
Net Weekly Circulation (NWC)
The estimated number of television households viewing a particular station at least once per week, Monday-Sunday, 6:00 am to 2:00 am, EST. Used to determine whether a station is "significantly viewed" in an area and must be carried by a cable system operating in that area.
(1) Group of radio or television outlets linked by cable or microwave that transmit identical programs simultaneously, or the company that produces programs for them. (2) Collection of computers or other devices that communicate with one another over telecommunications networks.
Network Address Translation (NAT)
A function, typically employed in internet connections, that performs address translation. Or a method by which IP addresses are mapped from one group to another, transparent to end users.
Network Address Translation Gateway
NAT gateways operate very much like a router, except messages they receive are addressed to them, not the actual destination of the message—a feature that allows a NAT gateway to connect an entire LAN to the Internet using a single TCP/IP address. When a NAT gateway receives a message from the Internet, it examines the two-byte port number at the end of the To address, looks the port number up in a table, and does a Network Address Translation (NAT) to point the message to the actual TCP/IP address for the destination of the message. To send a message from a computer on a LAN to a destination on the Internet, NAT gateways reverse the process, except they look at the message's From address, records the From address in its port number table, then replaces the From address with its own TCP/IP address and designated port number assignment.
Network Call Signaling (NCS)
A PacketCable signaling protocol based on MGCP for use in a centralized call control architecture, and assumes relatively simple client devices.
Network Congestion
A state of overload within a network, where there is a risk of traffic loss or service degradation.
Network Driver Interface Specification (NDIS)
Microsoft's version of the software interface between the transport protocol and the data link protocol, which allows multiple protocol stacks to run over one network adapter.
Network Interface Card (NIC)
A hardware interface card that connects a computer to the network cabling.
Network Interface Device (NID)
Generally an ADSL term, a NID is the interface between the local loop connection to a DSLAM in a Telco Central Office and the customer premise POTS and 10Base-T Ethernet (or other) local computer connection.
Network Layer
Layer 3 in the Open System Interconnection (OSI) architecture that provides network information that is independent from the lower layers; the layer that provides services to establish a path between open systems.
Network Management
The functions related to the management of data across the network.
Network Management OSS
The functions related to the management of data link layer and physical layer resources and their stations across the data network supported by the hybrid fiber/coax system.
Network Operations Center (NOC)
A large group which is responsible for the day-to-day operations and maintenance of a network.
Network Termination
Part of the Access Network, (owned by the carrier or the subscriber) located on the side of the subscriber's home. The following are functions of the Network Termination: coupling of home wiring to the carrier wiring, grounding, RF filtering, splitting, media conversion, remodulation, security and interdiction, provisioning, loopback testing by the carrier.
Network Time Protocol (NTP)
An internet standard used for synchronizing clocks of elements distributed on an IP network.
New Entrant Carrier (NEC)
This term is generally applied to new providers of competitive local exchange telephone services.
(1) An addressable unit in a network, which can be a computer, workstation or some type of communications control unit. (2) Point in a cable television system that interconnects traditional coaxial cable and fiber-optics. The place where an optical signal is converted to a radio frequency (RF) signal, or vice versa.
The word "noise" is a carryover from audio practice. Refers to random spurts of electrical energy or interference. May produce a "salt-and-pepper" pattern over the picture. Heavy noise is sometimes called "snow."
Noise Figure
A measure of the ability of an amplifier to increase the strength of a signal while adding the minimum possible self-generated noise. It is mathematically equal to ten times the log of the input S/N ratio to the output S/N ratio.
Non Repudiation
The ability to prevent a sender from denying later that he or she sent a message or performed an action.
A random value used only once that is sent in a communications protocol exchange to prevent replay attacks.
North American ISDN Users Forum (NIUF)
An association of ISDN product manufacturers and telephone company concerns dedicated to setting standards for the implementation of ISDN. They are, among other things, responsible for the formation of the National ISDN-1 standard, standard ISDN Order Codes (like Easy ISDN 1), and ISDN Feature Set Codes.
North American Number Plan (NANP)
The body that assigns three digit area codes for the United States, Canada and the Caribbean. Or the method of identifying telephone lines and area codes in the public network of North America.
Numbering Plan Area (more commonly known as area code) NXX (sometimes called exchange) represents the next three numbers of a traditional phone number. The N can be any number from 2-9 and the Xs can be any number. The combination of a phone number's NPA-NXX will usually indicate the physical location of the call device. The exceptions include toll-free numbers and ported numbers (see LNP).
Number Portability
A capability that permits telecommunications users to maintain the same telephone access number as they change telecommunication suppliers.
Object Carousel
An object carousel is a repetitively broadcast file system.
Object Identification (OID)
A sequence of integers used to traverse an SNMP managed object tree to find a specific managed object.
OCAP™ 1.0 implementation
The OCAP 1.0 implementation is the actual software that provides support for the defined OCAP 1.0 on a host receiver.
OCAP API refers to one of the Java APIs standardized as part of the OCAP 1.0 Specification. For the OCAP 1.0 implementation, the OCAP APIs include the DVB- J APIs that have been modified and/or extended by this specification.
Off the Air
Reception of a TV signal that has been broadcast through the air.
Office of Telecommunications Policy (OTP)
Division of the staff of the Executive Office of the President that advises the Executive Branch on communications policy, studies policy questions, and develops legislative proposals.
Off-Net Call
A communication connecting a PacketCable subscriber to a user on the PSTN.
The standard unit of resistance, reactance and impedance. A resistant of 1 ohm will conduct 1 ampere of current when a voltage of 1 volt is placed across it.
On-demand Service
A type of telecommunication service in which the communication path is established almost immediately in response to a user request brought about by means of a user-network signaling.
One-way Hash
A hash function that has an insignificant number of collisions upon output.
One-Way System
The ability to receive TV programming through the broadband network. Customers wanting to order movies and other services must use traditional methods to do so rather than using the two-directional interactive capabilities offered through the Two-Way System. As the physical plant is upgraded, one-way systems will be replaced by two-way systems.
On-Net Call
A communication placed by one customer to another customer entirely on the PacketCable Network.
Open Systems Interconnection (OSI)
A framework of the International Organization for Standardization (ISO) standards for communication between different systems made by different vendors, in which the communications process is organized into seven different categories that are placed in a layered sequence based on their relationship to the user. Each layer uses the layer immediately below it and provides a service to the layer above. Layers 7 through 4 deal with end-to-end communication between the message source and destination, and layers 3 through 1 deal with network functions.
OpenCable is an initiative led by CableLabs on behalf of its members, seeking to set a common set of requirements for interoperable digital set-top boxes, television receivers and other advanced digital devices manufactured by multiple vendors. These devices would be capable of delivering digital video, data and interactive services to a television set. See also CableCARD™, OCAP™.
OpenCable™ Application Platform (OCAP™)
The OpenCable Application Platform is a software interface specification that completely defines the OpenCable host software interface that executes OpenCable portable, interactive applications and services. OCAP is a separate effort from the Advanced Television Enhancement Forum (ATVEF) content specification, but OCAP does call for support and extension of ATVEF as a part of the PE requirements.
OpenCable™ Device
An OpenCable device is an OpenCable-compliant digital set-top converter or cable ready digital television receiver, allowing reception of existing cable television channels and providing the user interface for future, interactive applications.
OpenCable™ Unidirectional Receiver (OCUR)
This is a device that uses a CableCARD™ to get conditional access protected broadcast digital content from a cable television provider, protect it with a CableLabs approved digital rights management (DRM) system, and send it out over the digital rights interface (DRI) to a home media server (HMS). Currently, the only approved digital rights management (DRM) is Windows Media DRM (WMDRM). The only HMS approved so far is the Microsoft Media Center Edition (MCE) running on a Microsoft Vista operating system. Authorized use of OpenCable� unidirectional receiver (OCUR) and any associated DRM systems are controlled by CableCARD host interface licensing agreement (CHILA).
Operating System (OS)
The software that manages hardware and resources on a computer. Applications use the operating system to make requests for services and interact with the computer's devices. Or the software that controls the underlying hardware, performs the most basic functions for managing the resources of the hardware, and provides services to other software such as applications.
Operation Systems Support (OSS)
The back office software used for configuration, performance, fault, accounting and security management.
Optical Fiber
An extremely thin, flexible thread of pure glass, able to carry one thousand times the information possible with traditional copper wire.
Optical Overload
A condition of high input current that causes pulse width distortion at the output of the TIA.
Organizationally Unique Identifier (OUI)
A 3-octet Institute of Electrical and Electronic Engineers (IEEE) assigned identifier that OUI can be used to generate universal local area network (LAN) media access control (MAC) addresses and Protocol Identifiers per ANSI/IEEE Std 802 for use in Local and Metropolitan Area Network applications.
Out-of-Band Channel (OOB)
An out-of-band channel is the combination of the forward and reverse out-of-band communications channels. The OOB channel provides an IP-based communication channel between the network and the digital set-top converter.
Out-Of-Band-Forward-Data-Channel (OOB-FDC)
The portion of the cable RF range that is used to deliver system or service information to a receiver. Its frequency range is generally 70-130 Mz.
Out-Of-Band-Reverse-Data-Channel (OOB-RDC)
The portion of the cable RF range that is used to deliver data from the home receiver to the headend. Its frequency range is 5-40 Mz.
A company that overbuilds an incumbent telecommunications operator and offers customers a competitive alternative, generally with highly advanced fiber-optic networks. See also CLEC.
Overlapping Markets
A case where a TV stations Predicted Grade B Contour is overlapped by the Predicted Grade B Contour of a television station located in a different market.
A series of bits containing data and control information, including source and destination node addresses, formatted for transmission from one node to another.
Packet Identifier (PID)
A unique integer value used to identify elementary streams of a program in a single- or multi-program MPEG-2 stream.
Packet Internet Grouper (PING)
It is an Internet utility that verifies the connection between your computer and another IP address by sending packets to the address and checking for a response.
Packet Loop
A digital loop on which all information (signaling and user content) is encoded in packets.
Packetized Elementary Streams (PES)
An MPEG stream is composed of one or more elementary streams (ES), each containing audio, video or data. ES's can be grouped into Program Streams, which are formed by breaking ES's into chunks, the PES's, and interleaving them.
Packet-switched Network (PSN)
A PSN transports information by breaking up the bit stream into addressable digital "packets" that are transmitted independently and then reassembled in the correct sequence at the destination. Because these networks allow "sharing" of communications links, they are more efficient than circuit-switched networks.
A partial or complete failure of interlace in which the scanning lines of alternate fields do not fall exactly between one another but tend to fall (in pairs) one on top of the other.
Partial Grant
A grant that is smaller than the corresponding bandwidth request from the CM.
Passive Component
A component that requires no external source of power for it to function.
Passive Device
A circuit or network not using active devices such as tubes or transistors.
A sequence of characters used to prevent unauthorized access to a computer or its files. It is entered along with its corresponding user ID, which are then compared against a list of authorized users before access is granted.
Pay Cable
Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Premium Cable.
Pay Cable Unit
Each premium service to which a household subscribes is counted as one unit.
Pay Programming
Movies, sports, and made-for-cable specials that are available to the cable customer for a charge in addition to the basic fee.
Payload Header Suppression
The suppression of the header in a payload packet, e.g., the suppression of the Ethernet header in forwarded packets.
Payload Service Class Table (PSC)
A MIB table that maps RTP Payload Type to a Service Class Name.
Payload Unit Start Indicator (PUSI)
A flag in an MPEG header. A value of 1 indicates the presence of a pointer field as the first byte of the payload.
Pay-Per-View (PPV)
Pay television programming for which cable subscribers pay a separate fee for each program viewed. Or a service that allows customers to buy content on a program by program basis. Most customers today order programming via phone. OCAP 1.0 systems will enable the development of services to allow customers to order pay-per-view programming directly from their TV.
Peer Entities
Entities within the same layer.
Ratio of the number of cable customers to the total number of households passed by the system.
Per Hop Behavior (PHB)
In the IETF Differentiated Services (DiffServ) approach to quality of service differentiation, the treatment by a network router or switch of a group of network traffic flows for the "hop" to the next router switch. Packets "marked" or "tagged" with a common service classification in the packet header are aggregated into flow "bundles" which are treated the same, e.g., have the same priority or the same risk of being discarded in the event of network congestion.
Percentage Sync
The ratio, expressed as a percentage, of the amplitude of the synchronizing signal to the peak-to-peak amplitude of the picture signal between blanking and reference white level.
Performance Standards
The minimum technical criteria that must be met by cable television systems, consistent with standard set by the FCC or the local ordinance.
Per-Inquiry Advertising
Direct response advertising for which the cable network or system running the commercial is paid based on the number of responses received rather than the air time used.
Peripheral Component Interface (PCI)
An interface standard for connecting hardware expansion cards to a computer. The typical PCI connection is a slot, or edge-card connector, on the computer's motherboard allowing devices such as network cards, graphics cards or drive controllers to be connected to the computer. Some PCI devices are integrated onto the motherboard, especially in the case of "brand-name" computers. PCI has eclipsed ISA as the interface of choice due to its higher transfer rate, ease of configuration and improved Plug-and-Play ability.
Permanent Virtual Circuit (PVC)
A point-to-point connection between two specific locations on an ATM, Frame Relay, of X.25 network. PVCs are pre-defined by the ATM, Frame Relay, or X.25 network administrator. See also SVC.
Personal Communications Service (PCS)
Digital networks deployed in cellular; like configuration at 1.8GHz to 2.2GHz.
Personal Video Recorder (PVR)
A consumer device which uses a hard disk drive to record television programs based on the user's preferences. Also provides pause of live television feature. Or a set of equipment that allows a user to timeshift television without removable media.
A relative quantity describing the time relationship between or among waves having identical frequency. The complete wave cycle is divided into 360 equal parts, called degrees of phase.
Phase Distortion
When the output of an amplifier fluctuates in phase, even though the input does not, the circuit introduces phase distortion into the signal.
Phase Jitter
Phase variations arising in a channel and caused by incidental frequency modulation of signals transmitted over the channel. This occurs when the carrier supply frequencies in a frequency-division-multiplexed carrier system are not perfectly constant.
Phase Modulation
When the information is impressed on a radio frequency signal by varying its phase angle.
Phased Array
A type of antenna design that incorporates two or more elements that integrate signal information received from the spatially separate elements, and that transmit in a coordinated manner (either simultaneously or alternately).
POD Host Interface License Agreement.
A semiconductor device that converts light to electrical current.
A device that exhibits a variable resistance, depending on the amount of light that strikes it.
Physical (PHY) Layer
Layer 1 in the Open System Interconnection (OSI) architecture; the layer that provides services to transmit bits or groups of bits over a transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
Physical Media Dependent (PMD) Sublayer
A sublayer of the physical layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
Picture Element
One of many monochrome or color "dots" that make up a television picture.
Picture Tube
A cathode-ray tube used to produce an image by variation of the intensity of a scanning beam.
An abbreviation of the term "picture element." A pixel is the smallest picture element of a digital image; the smallest unit that can be displayed on a monitor. Like the fibers of a fabric, individual pixels are too small to notice, but together they make up the whole. The smaller the pixels, the higher the resolution. All images are composed of pixels.
Plain Old Telephone Service (POTS)
This term often is used to refer to analog voice telephone services provided over the public switched telephone network.
Plain Text
The original (unencrypted) state of a message or data. Also called cleartext.
Plastic Optical Fiber (POF)
A plastic cable used, for short distances only, as an alternative to fiber optic cable. Although plastic is not as transparent as glass, it is more malleable and less expensive. POF is a possible choice for indoor networking.
An Intel-developed hardware standard created to automate the setup and configuration of hardware devices connected to a computer. In theory, it allows you to "plug" a device into the computer and "play" it without going through a complicated setup process.
A plug-in refers to a set of functionality which can be added to a generic platform in order to provide interpretation of DVB registered, but non-DVB-J, application formats. For example, HTML3.2 or MHEG-5 are examples of plug-ins.
Plug-in Application
A plug-in application refers to an application that conforms to an application format for which a plug-in has been registered with DVB and which is only interoperable within terminals which have the appropriate plug-in resident or connected to networks where an appropriate plug-in is being broadcast.
Point-of-Deployment (POD) Module
Now referred to as CableCARDs. See also CableCARD™.
Point-of-Presence (POP)
The point where the inter-exchange carrier's responsibilities for the line begin and the local exchange carrier's responsibility ends. Location of a communications carrier's switching or terminal equipment.
A circuit connecting two nodes only, or a configuration requiring a separate physical connection between each pair of nodes.
Point-to-Point Protocol (PPP)
A method of transmitting TCP/IP and other networking protocols over a dial-up or WAN connection.
Pole Attachment
When cable television systems use existing pole lines maintained by utilities, an attachment contract must be negotiated between the parties of interest.
The physical connector on a device enabling the connection to be made.
Post Office Protocol 3 (POP3)
The current version of the most common protocol for receiving e-mail on a TCP/IP network.
Power Amplifier
An amplifier that delivers a certain amount of alternating-current power to a load. Used in audio frequency and radio frequency applications.
Power Cycle
The act of turning the electrical power to a device off and then back on, often used to reset the device.
Power Gain
An increase in signal power between one point and another. Used as a specification for power amplifiers.
Power Transistor
A semiconductor transistor designed for power-amplifier applications at audio and radio frequencies.
Predicted Grade A Contour
The line representing the service area in which a good picture is computed to be available 90 percent of the time at 70 percent of the receiver locations. Signal contours determine what educational channels are carried on a cable system and, in similar markets, what stations must be carried from other small markets.
Predicted Grade B Contour
The concentric area marking a television station's service area in which a good analog picture is computed to be available 90 percent of the time at 50 percent of the receiver locations.
Premium Cable
Cable programming services for which subscribers pay an additional fee above the basic cable service charge. Also called Pay Cable.
Presentation Engine (PE)
In OCAP, the presentation engine is responsible for the appearance of information on the user interface (the display), and enables content to be displayed on a variety of devices. The PE incorporates native code that decodes text (HTML, ECMAScript) into meaningful operations, and utilizes Web-based software from the computer world, the Web browser. However, the PE has only limited ability to perform complex logic and arithmetic operations and lacks the security of the Execution Engine, which is why the EE is also required by OCAP.
Pre-Shared Key
A shared secret key passed to both parties in a communication flow, using an unspecified manual or out-of-band mechanism.
Primary Rate Interface (PRI)
An ISDN PRI is an industrial-strength ISDN telephone connection commonly used to service multiple dial-up data connections, large central switchboard "PBX" systems, and other highly-specialized needs. Each ISDN PRI has twenty-three 56 or 64Kbps B Channels and one 64Kbps D Channel.
Primary Service Flow
All CMs have a Primary Upstream Service Flow and a Primary Downstream Service Flow. They ensure that the CM is always manageable and they provide a default path for forwarded packets that are not classified to any other Service Flow.
A way to ensure that information is not disclosed to any one other than the intended parties. Information is usually encrypted to provide confidentiality. Also known as confidentiality.
Private Branch Exchange (PBX)
A private switching system, either manual or dial, usually serving an organization such as a business company or a government agency and usually located on the customer's premises.
Private Key
The key used in public key cryptography that belongs to an individual entity and must be kept secret.
Processing Gain
A function of spread spectrum CDMA technology used in digital cellular; a measure of the robustness of the system; recovers the processed low power signal used to eliminate noise.
A record stored on a computer containing the settings and preferences for each of the users sharing that computer. Profiles can be set up in Windows, as well as Netscape and other shared Internet applications, and are also used to enable security features in a program (e.g., separate e-mail profiles). Or a profile is a description of a series of minimum configurations, defined as part of the specification, providing different capabilities of the OpenCable system. A profile maps a set of functions which characterize the scope of service options. The number of profiles is small. The mapping of functions into resources and subsequently into hardware entities is out of the scope of the specification and is left to manufacturers.
Program and System Information Protocol (PSIP)
A transport and data format specification formulated by the Society of Cable and Telecommunications Engineers (SCTE) to deliver Service Information to the receiver. See also Service Information.
Program Map Table (PMT)
This is an MPEG-2 entity that contains all of the PIDs that make up a program.
Program Non-duplication
Under FCC rules, a cable system must black-out the programming of a distant television station it carries when the system would duplicate a local station's programming, on the request of the local station.
Program Stream
In MPEG-2, a multiplex of variable-length digital video and audio packets from one or more program sources having a common time-base.
Program-Specific Information (PSI)
In MPEG-2, normative data necessary for the demultiplexing of Transport Streams and the successful regeneration of programs.
The set of rules or standards which enables communication between computers on a network. In its simplest form, a protocol is the language used by two computers to transfer information. Or a set of rules and formats that determines the communication behavior of layer entities in the performance of the layer functions.
Protocol Data Unit (PDU)
A packet of data passed across an IP network.
Provisioned Service Flow
A Service Flow that has been provisioned as part of the Registration process, but has not yet been activated or admitted. It may still require an authorization exchange with a policy module or external policy server prior to admission.
A telephone company term meaning to configure. Before an ISDN line can be used, it has to be correctly provisioned to work with the ISDN equipment the customer is installing and enabled for the various options the customer has requested.
A facility that indirectly provides some service or acts as a representative in delivering information, thereby eliminating the need for a host to support the service.
Proxy Server
A network component between a LAN and the Internet providing security, administrative control and data caching. It is also a firewall that protects the network from intrusion.
Public Access
A non-commercial channel set aside by a cable system for use by the public, on a first come first serve, non-discriminatory basis.
Public Key
The key used in public key cryptography that belongs to an individual entity and is distributed publicly. Other entities use this key to encrypt data to be sent to the owner of the key.
Public Key Certificate
A binding between an entity's public key and one or more attributes relating to its identity, also known as a digital certificate.
Public Key Cryptography
A procedure that uses a pair of keys, a public key and a private key, for encryption and decryption, also known as an asymmetric algorithm. A user's public key is publicly available for others to use to send a message to the owner of the key. A user's private key is kept secret and is the only key that can decrypt messages sent encrypted by the user's public key.
Public Key Cryptography for Cross-Ream Authentication (PKCROSS)
Utilized PKINIT for establishing the inter-realm keys and associated inter-realm policies to be applied in issuing cross-realm service tickets between realms and domains in support of Intradomain and Interdomain CMS-to-CMS signaling (CMSS).
Public Key Cryptography for Initial Authentication (PKINIT)
The extension to the Kerberos protocol that provides a method for using public key cryptography during initial authentication.
Public Key Cryptography Standards (PKCS)
Published by RSA Data Security Inc., these standards describe how to use public key cryptography in a reliable, secure and interoperable way.
Public Key Infrastructure (PKI)
The architecture, organization, techniques, practices, and procedures that collectively support the implementation and operation of a Certificate-based public key cryptographic system. Also a process for issuing public key certificates, which includes standards, Certification Authorities, communication between authorities and protocols for managing certification processes.
Public Switched Telephone Network (PSTN)
The PSTN is the worldwide circuit-switched telephone network. Once only an analog system, telephone networks today increasingly are digital, even though most subscribers are connected via analog circuits. Or the international telephone system based on copper wires carrying analog voice data.
Public Switched Telephone Network Media Gateway (PMG)
A media gateway located within the backbone of the PacketCable™ network which "bridges" calls between the Internet Protocol (IP)-network and the PSTN-network. The PSTN media gateway is responsible for supporting all management interfaces to the PSTN and also supports switching system number 7 (SS7) signaling and various time-domain interface options (e.g., channelized T-1 trunks).
Public Television
Noncommercial television broadcasting.
Pull Mode
The delivery method in which a subscriber demands and receives data from the provider.
Pulse Code Modulation (PCM)
The internationally accepted Codex used by telephone companies to translate between the 56 and 64Kbps digital signaling technologies and the analog signals sent across POTS telephone lines. PCM codes are seven or eight bits in size, meaning each code byte has 128 or 256 possible values. (North American POTS connections generally only use 7 bit codes.) Or a commonly employed algorithm to digitize an analog signal (such as a human voice) into a digital bit stream using simple analog to digital conversion techniques.
Push Mode
A delivery method where the service provider transmits on a fixed, predictable schedule, or in response to an event such as the updating of data in the subscriber's database.
QoS Parameter Set
The set of Service Flow Encodings that describe the Quality of Service attributes of a Service Flow or a Service Class.
Quadrature Amplitude Modulation (QAM)
A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. A modulation scheme used by telecommunications providers. More advanced modulation offers increased capacity (e.g., 256 QAM offers greater capacity/transmission speeds than 64 QAM).
Quadrature Phase-Shift Keying (QPSK)
A method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits.
Quality-of-Service (QoS)
Guarantees network bandwidth and availability for applications. Any real time media stream that crosses a DOCSIS access link needs to be given prioritized traffic management treatment in order to assure the best user-perceived quality end-to-end. DOCSIS 1.1 and PacketCable provide several potential methods for classifying traffic (ranging from DIFFSERV to flow-classification) and several access-link traffic management functions, which can be applied to such classified traffic (priority, CBR real-time polling, header compression, stream specific modulation methods). PacketCable enables on-demand, real-time bandwidth management of DOCSIS QoS sessions.
Radio Frequency (RF)
Analog electrical signals sent over the cable. Conventional (broadcast) television and radio, as well as cable TV, deliver RF signals to your television/radio. RF is quickly becoming yesterday's news to many cable TV providers who are installing fiber-optic lines that will replace today's cables. Or in cable television systems, this refers to electromagnetic signals in the range 5 to 1000 MHz.
Radio Frequency Interference (RFI)
Undesired signals received by a user; those signals that miss their desired user become interference energy to users in the same or adjacent cells.
The process by which a cable modem learns its distance from the headend. Ranging is a continual process, due to the expansion and contraction of cable that occurs during the day.
The scanned (illuminated) area of the cathode ray picture tube.
Real-time Protocol/Real-time Control Protocol (RTP/RTCP)
The Internet Engineering Task Force (IETF) specification for audio and video signal management. RTP provides end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video or simulation data, over multicast or unicast network services. The data transport is augmented by a control protocol (RTCP) to allow monitoring of the data delivery in a manner scalable to large multicast networks, and to provide minimal control and identification functionality. RTP and RTCP are designed to be independent of the underlying transport and network layers.
The act of reloading the operating system of a computer, usually by resetting the power to the computer with the power switch, or selecting Start/Shutdown/Restart in Windows.
The physical upgrade of a cable system, often involving the replacement of amplifiers, power supplies, passive devices and sometimes the cable, strand, hardware and subscriber unit.
Electronic device which can convert electromagnetic waves into either visual or aural signals, or both. For cable television, usually the subscriber's television set.
Receiver Isolation
The attenuation between any two receivers connected to the system.
Record Keeping Server (RKS)
In a PacketCable network, the RKS is responsible for accepting partial billing information generated by a distributed set of PacketCable elements and correlating this information into a single coherent record that describes the resources used during the service.
Reflection Coefficient
Ratio of reflected wave to incident wave.
Reflections or Echoes
In video transmission this may refer either to a signal or to the picture produced. In a signal it is either waves reflected from structures or other objects or waves which are the result of impedance or other irregularities in the transmission medium. In a picture, "Echoes" observed in the picture produced by the reflected waves.
Regional Bell Operating Company (RBOC)
RBOC comprises the U.S. local carriers created in the 1982 Consent Degree to break up AT&T. Seven were formed to serve as parent companies for the 22 then-existing Bell Operating Companies.
Registration, Admission, and Status (RAS)
RAS Channel is an unreliable channel used to convey the RAS messages and bandwidth changes between two H.323 entities.
Remote Access Dial-In User Service (RADIUS)
An internet protocol (IETF RFC 2138 and RVC 2139) originally designed for allowing users dial-in access to the internet through remote servers. Its flexible design has allowed it to be extended well beyond its original intended use.
Remote Method Invocation (RMI)
A Java programming feature that allows a program running on one computer to access the objects and methods of another Java program running on a separate computer.
A repeater is a network device that repeats signals from one cable onto one or more other cables, while restoring signal timing and waveforms.
The term given to the process of resetting a cable modem by removing its entry from the cable router, then adding it back on to re-establish the connection.
Resident Application
A resident application is an application that is saved on the host device and may be run at any time. Resident applications, such as the monitor application or EPG, are typically responsible for host device control.
Residential Gateway
A part of the Access Network which adds network functionality and multiplexes different services. The gateway must perform the basic functions of media translation and address translation.
The opposition that a substance offers to the flow of electric current.
An electronic component that is deliberately designed to have a specific amount of resistance.
A measure of picture resolving capabilities of a television system determined primarily by bandwidth, scan rates and aspect ratio. Relates to fineness and details perceived.
Resolution (Horizontal)
The amount of resolvable detail in the horizontal direction in a picture. It is usually expressed as the number of distinct vertical lines, alternately black and white, which can be seen in three-quarters of the width of the picture. This information usually is derived by observation of the vertical wedge of a test pattern. A picture which is sharp and clear and shows small details has good, or high, resolution. If the picture is soft and blurred and small details are indistinct it has poor, or low, resolution. Horizontal resolution depends upon the high-frequency amplitude and phase response of the pickup equipment, the transmission medium and the picture monitor, as well as the size of the scanning spots.
Resolution (Vertical)
The amount of resolvable detail in the vertical direction of a picture. It is usually expressed as the number of distinct horizontal lines, alternately black and white, which can be seen in a test pattern. Vertical resolution is primarily fixed by the number of horizontal scanning lines per frame. Beyond this, vertical resolution depends on the size and shape of the scanning spots of the pickup equipment and picture monitor and does not depend upon the high-frequency response or bandwidth of the transmission medium or picture monitor.
Resource reSerVation Protocol (RSVP)
An Internet protocol used for negotiating end-to-end IP quality of service (QoS) within the network. In a PacketCable-based network, RSVP can be used to negotiate QoS on the cable access network. Or IETF resource reservation setup protocol for IP networks.
Response Time
The length of time between the occurrence of an event and the response of an instrument or circuit to that event.
Return Channel
A return channel refers to the communications mechanism that provides connection between OpenCable and a remote server.
Return Loss
The parameter describing the attenuation of a guided wave signal (e.g., via a coaxial cable) returned to a source by a device or medium resulting from reflections of the signal generated by the source.
Return Path
The term used to describe traffic and paths that go from the subscriber to the headend. Also known as Upstream, or Reverse Path.
Reuse/Frequency Reuse
The utilization of frequency (channels) more than once in a wireless network; equated primarily with the basic cellular grid design, where each cell uses each channel once within its boundaries and is insulated from other cells using that frequency to allow for anticipated interference; due to the shortcomings of conventional transmission techniques, frequency reuse in adjacent cells has been largely implausible until the recent development of spatial processing technology, which can enable same-cell frequency reuse.
Revenue Generating Unit (RGU)
Commonly referred to one additional cable subscription unit. For example, a customer who signs up for digital video and high-speed Internet access is counted as two RGUs, because the customer is signing up for two subscriptions.
Reverse Channel
The direction of signal flow toward the headend, away from the subscriber; equivalent to upstream.
Reverse Path Forwarding
A technique where a router receives a packet, then floods the packet out on all paths, except the path on which it received the packet.
R-F Pattern
A term sometimes applied to describe a fine herringbone pattern in a picture. May also cause a slight horizontal displacement of scanning lines resulting in a rough or ragged vertical edge of the picture. Caused by high-frequency interference.
Using the secondary mouse button (usually the right button) to open context menus.
A network topology in which the nodes are connected in a closed loop. Data is transmitted from node to node around the loop, always in the same direction.
An oscillatory transient occurring in the output of a system as a result of a sudden change in input. Results in close-spaced multiple reflections, particularly noticeable when observing test patterns, equivalent square waves, sine-squared signal, or any fixed objects whose reproduction requires frequency components approximating the cutoff frequency of the system.
Rivest Cipher 4 (RC4)
A variable length stream cipher. Optionally used to encrypt the media traffic in PacketCable.
RJ-11 Jack/Connector
An RJ-11 connector is the small, modular plug used for most analog telephones. It has six pin slots in the head, but usually only two or four of them are used.
RJ-45 Jack/Connector
An RJ-45 connector is similar in appearance to a modular RJ-11 connector, but is wider and has eight-pin slot positions instead of six. RJ-45 connectors are used to connect ISDN S/T Interfaces and for 10-Base-T, 100Base-T, or 1000Base-T Ethernet cabling.
The practice of stripping commercials in designated time periods across multiple cable channels. Can be an effective method for catching channel surfers.
A gradual attenuation of gain-frequency response at either or both ends of the transmission pass band.
Root Private Key
The private signing key of the highest-level Certification Authority. It is normally used to sign public key certificates for lower-level Certification Authorities or other entities.
Root Public Key
The public key of the highest level Certification Authority, normally used to verify digital signatures generated with the corresponding root private key.
Routers are special network devices used to connect one recognized computer network to another. Routers work like a postal worker; they examine the To addresses of network messages they are given and use part of the address like a zip code to figure out which computer network to send it to. Once a router has figured out which network the message should go to, it sends the message to another router, which repeats the process until the last router in the chain sends it directly to the computer listed in the destination address. Most WANs use routers to connect one LAN location to another.
Routing Information Protocol (RIP)
A protocol of the Internet Engineering Task Force (IETF) for exchanging routing information about Internet Protocol (IP) networks and subnets.
A public-key, or asymmetric, cryptographic algorithm that is used to provide the services of authentication and encryption. RSA stands for the three inventors of the algorithm; Rivest, Shamir, Adleman.
RSA Key Pair
A public/private key pair created for use with the RSA cryptographic algorithm.
S/T Interface
The eight-pin RJ-45 connector on the "back side" of an NT-1 or ISDN adapter that connects one or more ISDN adapters to the NT-1. Of the eight pins on the RJ-45 connector, the outside two pins on each side provide power, and the center four form a "transmit" and "receive" pairs. ISDN adapters with built-in NT-1s do not have an S/T Interface.
In analog to digital signal processing, a sample is taken at regular intervals to establish the electrical potential (voltage) present in an analog system at a given point in time. Each sample is then assigned a digital value. In telephony, sample values are established by a codex, and range from zero to 255. (Though, for most "voice grade" connections the actual range of codex values is between zero and 127.) Each sample value is transmitted across the digital phone network and used to re-create a facsimile of the original analog signal at the other end of a phone connection.
Sample Rate
In analog to digital signal processing, the sample rate is the interval at which samples of an analog signal are taken. The sample rate for digital telephony, for example, is 8000 per second.
Unsigned applications and signed applications without a permission file have access to all the APIs for which there is no permission signaling defined. This is commonly called the sandbox.
Device located in geostationary orbit above the earth which receives transmissions from separate points and retransmits them to cable systems, DBS and others over a wide area.
Satellite Dish Antenna
A system for concentrating the weak signals sent from a satellite.
Satellite Downlink
A data service that broadcasts data from an orbital satellite to terrestrial receivers. Used by some satellite TV vendors to provide a high-speed feed for receiving data from the Internet. Data sent to the Internet (Web page requests, outbound e-mail, etc.) must be sent by more conventional means, such as a dial-up modem connections to a local ISP.
Satellite Master Antenna Television System (SMATV)
Systems that serve a concentration of TV sets such as an apartment building, hotel, etc., utilizing one central antenna to pick up broadcast and/or satellite signals. Or RF distribution of satellite and antenna signals.
Scanning Line
A single continuous narrow strip of the picture area containing highlights, shadows, and halftones, determined by the process of scanning.
A signal security technique for rendering a TV picture unviewable, while permitting full restoration with a properly authorized decoder or descrambler.
Second Audio Program (SAP)
In a BTSC-encoded television sound carrier, a monaural audio subcarrier that can be used to transmit supplemental foreign language translation audio or other information.
Second Harmonic
A second order beat whose two beating carriers have the same frequency.
Second Order Beat
An unwanted carrier created by two separate carriers beating against each other. These beating carriers may have the same or different frequencies.
Secret Key
The cryptographic key used in a symmetric key algorithm, which results in the secrecy of the encrypted data that depends solely on keeping the key a secret; also known as a symmetric key.
Secure Hash Algorithm 1 (SHA-1)
A standards-based method for computing a condensed representation of a message or a data file.
Secured Socket Layer (SSL)
Used to define standard encryption software to pass sensitive information over an unsecured Internet connection. SSL works on encryption of sensitive data using complex techniques and converting them back to original data using keys on the receiving side. Or a public key encryption based protocol for secure communications between client and server.
Security Association (SA)
A one-way relationship between sender and receiver offering security services on the communication flow.
Security Association Identifier (SAID)
Uniquely identifies Security Associations in the DOCSIS Baseline Privacy Plus Interface (BPI+) security protocol.
Selective Reception
A characteristic of spatial processing that monitors incoming signals and distinguishes between desirable information and interference; by filtering out interfering signals and appropriately combining the reception from all the antennas in the array, this approach provides significant improvement in signal quality.
A computer and/or software that provides and controls resources for clients on a network. These resources can include hardware devices such as printers and storage systems, or files as in the case of a Web server.
A service is a sequence of programs under the control of a broadcaster which can be broadcast as part of a schedule.
Service Access Point (SAP)
The point at which services are provided by one layer, or sublayer to the layer immediately above it.
Service Application
An application is service-bound if, and only if, it is associated with one or more broadcast services.
Service Class
A set of queuing and scheduling attributes that is named and that is configured at the cable modem termination system (CMTS). A Service Class is identified by a Service Class Name. A Service Class has an associated QoS Parameter Set.
Service Class Name
An ASCII string by which a Service Class may be referenced in modem configuration files and protocol exchanges.
Service Control Point (SCP)
A SCP is a node within a signaling system number 7 (SS7) network that provides centralized service logic and data, such as call routing information.
Service Data Unit (SDU)
The information that is delivered as a unit between peer service access points (SAPs).
Service Flow (SF)
A unidirectional flow of packets on the RF interface of a DOCSIS system. Or a MAC-layer transport service which provides unidirectional transport of packets from the upper layer service entity to the RF. It also shapes, polices and prioritizes traffic according to QoS traffic parameters defined for the Flow.
Service Flow Identifier (SFID)
A 32-bit integer assigned by the CMTS to each DOCSIS Service Flow defined within a DOCSIS RF MAC domain. Any 32-bit SFID must not conflict with a zero- extended 14-bit SID. SFIDs are considered to be in either the upstream direction (USFID) or downstream direction (DSFID). USFIDs and DSFIDs are allocated from the same SFID number space.
Service Identifier (SID)
An identifier appearing in the DOCSIS media access control (MAC) allocation map message, which identifies the entities which may make use of a particular upstream bandwidth assignment. A cable modem may have one or more unicast SIDs. A group of cable modems may share a multicast SID.
Service Information (SI)
That information that describes the broadcast services available on the network.
Service Profile Identifier (SPID)
A number that the telephone company switching equipment uses to keep track of configuration information for each terminal adapter connected to an ISDN telephone line. The telephone company should give you your SPIDs at the time they assign you your ISDN directory numbers.
Session Description Protocol (SDP)
A DDE-1 protocol that defines a multicast session that may or may not be concurrent with a TV program. Or IETF protocol that describes multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation.
Session Initiation Protocol (SIP)
An Internet protocol used for negotiating multimedia sessions across the network.
Session Key
A cryptographic key intended to encrypt data for a limited period of time, typically between a pair of entities.
Set-Top Box
Any of several different electronic devices that may be used in a customer's home to enable services to be on that customer's TV. If the "set-top" device is used only for extending the channels available, it is called a converter. If it restores scrambled or otherwise protected signals, it is a descrambler.
Shannon's Law
An arithmetic proof that defines the maximum data rate an analog device can achieve when sending information over a sampled, analog-to-digital connection when the analog device has no control over the timing of each individual sample. For the North American telephone system, which has a sample rate of 8,000 samples per second with a range of up to 128 sample values, Shannon's Law shows the maximum data rate that can be achieved over voice grade lines to be about 36Kbps.
The percent of television households tuned to a particular program or category of programming.
Shared Wired Network
A topology where multiple households connect to a common piece of wire.
Programs allowing customers to view products and/or order them by cable TV, including catalogues, shopping shows, etc.
Signal Leakage
Undesired emission of signals out of a cable television system.
Signal Switching Point (SSP)
SSPs are points within the signaling system number 7 (SS7) network that terminate SS7 signaling links and also originate, terminate, or tandem switch calls.
Signal Transfer Point (STP)
A STP is a node within signaling system number 7 (SS7) network that routes signaling messages based on their destination address. It is essentially a packet switch for SS7. It may also perform additional routing services such as Global Title Translation.
The process by which an end system notifies a network that it wants service.
Signaling Connection Control Part (SCCP)
This is a protocol within the signaling system number 7 (SS7) suite of protocols that provides two functions: (1) The ability to address applications within a signaling point. (2) Global Title Translation.
Signaling Gateway (SG)
A signaling agent that receives/sends switched circuit network (SCN) native signaling at the edge of the Internet protocol (IP) network. In particular the signaling system number 7 (SS7) SG function translates variants ISUP and TCAP in an SS7-Internet Gateway to a common version of ISUP and TCAP.
Signaling System Number 7 (SS7)
SS7 is an architecture and set of protocols for performing out-of-band call signaling with a telephone network.
Signal-to-Noise Ratio (SNR)
The sensitivity of a communications receiver is generally specified in terms of the audio signal-to-noise ratio that results from an input signal of a certain number of microvolts.
Signed and Sealed
An "envelope" of information which has been signed with a digital signature and sealed using encryption.
Simple Gateway Control Protocol (SGCP)
A call signaling protocol used for controlling media gateways from a call agent (or Call Management Server) within the network. SGCP was the precursor to the PacketCable Network-based Call Signaling (NCS) protocol.
Simple Mail Transfer Protocol (SMTP)
A TCP/IP protocol used to send e-mail on a network or to route e-mail on the Internet.
Simple Network Management Protocol (SNMP)
SNMP allows a TCP/IP host running an SNMP application to query other nodes for network-related statistics and error conditions. The other hosts, which provide SNMP agents, respond to these queries and allow a single host to gather network statistics from many other network nodes.
Skin Effect
The behavior whereby electricity migrates to the outside wall of a wire.
Difference in amplifier gain, or change in cable attenuation, between lowest and highest frequency present.
The action of a slope-compensated gain control, whereby slope of amplifier equalization is simultaneously changed with the gain so as to provide the correct cable equalization for different lengths of cable; normally specified by range and tolerance.
Small Office/Home Office (SOHO)
An industry term used to refer to a telecommunications market segment comprised of people working out of their homes or small offices.
A term used to describe a picture condition in which objects appear to be extended horizontally beyond their normal boundaries in a blurred or "smeared" manner.
Heavy random noise.
Society for Cable Telecommunications Engineers (SCTE)
A non-profit professional organization serving the cable industry by providing training, certification and standards.
Society for Motion Picture and TV Engineers (SMPTE)
A professional society for motion picture and TV engineers with more than 9,000 members worldwide. It prepares standards and documentation for TV production. SMPTE time code records hours, minutes, seconds and frames on audio or videotape for synchronization purposes.
Programming and programming materials such as films, videotapes, and slides.
Solid State
A term taken from physics, used interchangeably with the word transistorized; also includes other semiconductor elements, such as diodes. Generally refers to tubeless equipment.
Length of cable between amplifiers expressed as dB loss at the highest TV channel provided for in a system, equal to amplifier gain in main trunks.
Distance between line extenders or distribution amplifiers; also, distance between taps.
Spatial Diversity
An antenna configuration of two or more elements that are physically spaced (spatially diverse) to combat signal fading and improve signal quality; the desired spacing depends on the degree of multipath angle spread.
Spatial Division Multiple Access (SDMA)
A complement (not an alternative) to CDMA and TDMA, this technology increases the number of users that can access an existing wireless phone or data system by exploiting the spatial characteristics of the channel itself through highly developed implementation of an intelligent antenna system's capabilities for receiving and transmitting.
Special Effects Generator
A device permitting combinations of images on a television screen supplied by one or more video inputs.
Special Keycodes
Keycodes other than the Mandatory Ordinary Keycodes that have been reserved for special purposes by special applications such as the monitor application, or some other implementation-dependent application with special privileges, such that they will not be treated the same as the Mandatory Ordinary Keycodes and may not be available to the application that has focus.
Spectrum Management System (SMS)
A system for managing the radio frequency (RF) cable spectrum.
SPID Guessing
A process that can greatly simplify the process of installing an ISDN adapter. Given the regular 10-digit telephone number(s) assigned to an ISDN line, a SPID guessing algorithm tries combining the seven and 10-digit phone numbers with various prefixes and suffixes until it finds it can communicate with the phone company's central office switch. Once it discovers the right combination, the algorithm also can figure out the kind of central office switching system to which the adapter is connected.
A passive device (one with no active electronic components) which distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.
Sports Blackout
Federal law requires cable systems and television stations to delete coverage of local sports events to protect gate receipts.
Spot Revenue
Revenue gained from advertising that is placed on a cable system by a local or national advertiser.
Spread Spectrum
Enables the successful transmission to hostile transmission environments.
This term is used to designate the interval of time, in NVOD; that is, the time between the beginning of a movie or program, on one channel and the beginning of the same program on another channel. (Ex: A movie starts at 7:00 on channel 50, at 7:15 on channel 51, at 7:30 on channel 52-the movie is staggercast 15 minutes.)
Standalone MTA (S-MTA)
A single node that contains an MTA and a non-DOCSIS MAC (e.g., Ethernet).
Start Bits
A sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock, which dictates the intervals at which individual bits are expected to be sent and received.
Stop Bits
A sequence of bits sent by a device transmitting data so that the device receiving the data can synchronize its clock, which dictates the intervals at which individual bits are expected to be sent and received.
Store and Forward
Technique for examining incoming packets on an Ethernet switch or bridge whereby the whole packet is read before forwarding or filtering takes place. Store and forward is a slightly slower process than cut-through, but it does insure that all bad or misaligned packets are eliminated from the network by the switching device.
A term used to describe a picture condition in which objects appear to be extended horizontally beyond their normal boundaries.
Stream Control Transmission Protocol (SCTP)
IETF protocol that supports reliable data exchange between two endpoints.
Streaming Media
Digital Video, Audio, and Data Services that are selectively delivered to individual users, either in response to a user request or based upon a user profile. These services are delivered over a data transport stream, either via real-time transmission to the user, or via off-peak data-carousel transmission to a storage device at or near the user's location for subsequent retrieval.
Subscriber; a cable customer.
Sub Band
The frequency band from 6 MHz to 54 MHz, which may be used for two-way data transmission.
A unidirectional flow of IP packets characterized by a single source and destination IP address and single source and destination UDP/TCP port.
A subdivision of a layer in the Open System Interconnection (OSI) reference model.
Subnetworks are formed by connecting adjacent nodes physically with transmission links.
Subnetwork Access Protocol (SNAP)
An extension of the LLC header to accommodate the use of 802-type networks as Internet Protocol (IP) networks.
A household or business that legally receives and pays for cable and/or pay television service for its own use. Alternate definition is: The entity that is the subject of, and has been issued, a Certificate. The Subscriber is capable of using, and is authorized to use, the private key that corresponds to the public key listed in the Certificate.
Subscriber Media Gateway (SMG)
A media gateway located within the subscriber's network which "bridges" calls between the Internet Protocol (IP) network and the subscribers' telephones (or telephony-type devices). Typically such a media gateway provides an external interface to one or more 2500-type telephony handsets and also supports common standard add-on devices such as caller-id display units and message-waiting lights.
Subscriber Unit
The fixed, typically wall-mounted equipment used by the subscriber in a wireless local-loop system to send and receive messages; a standard telephone is attached to it by wire to complete the connection to the user.
A frequency-division scheme that allows bi-directional traffic on a single cable. Reverse path signals come to the headend from 5 to 30 (up to 42 on extended subsplit systems) MHz. Forward path signals go from the headend from 50 or 54 MHz to the upper frequency limit of the cable network.
An element in a hierarchical division of an open system that interacts directly with elements in the next higher division or the next lower division of that open system.
The band of cable television channels J through W lying between 216 MHz and 300 MHz.
Originally referred to television station WTBS in Atlanta; now generally used to describe any broadcast TV station that has its signal distributed nationally by satellite.
Supplemental Ordinary Keycodes
Keycodes other than the Mandatory Ordinary Keycodes that have not been reserved for special purposes, and thus will be treated the same as the Mandatory Ordinary Keycodes, i.e., will be available to the application that has focus.
A mechanical or electrical device that is used to deliberately interrupt or alter the path of the current through the circuit. Also could be used to refer to a switched hub, a device used for connecting Ethernet LANs.
Switched Circuit Network (SCN)
Synonym for the Public Switched Telephone Network.
Switched Network
Any network in which switching is present and is used to direct messages form the sender to the ultimate recipient. Usually switching is accomplished by disconnecting and reconnecting lines in different configurations in order to set up a continuous pathway between the sender and the recipient.
Switched Service
A cable communications service in which each subscriber has a terminal and may communicate with any other subscriber.
Switched Virtual Circuit (SVC)
Allow an end-user to establish on-demand data connections between two end points on an ATM, Frame Relay, or X.25 network. See also Permanent Virtual Circuit (PVC).
A control which permits the selection of one image from any of several cameras to be fed into the television display or recording system.
A device permitting gradual, overlapping transition from the image of one camera to another. Sometimes incorporated as part of a special effects generator.
Symmetric Key
The cryptographic key used in a symmetric key algorithm—an algorithm for cryptography that uses the same cryptographic key to encrypt and decrypt messages.
An abbreviation for the words "synchronization", "synchronizing", etc. Applies to the synchronization signals, or timing pulses, which lock the electron beam of the picture monitors in step, both horizontally and vertically, with the electronic beam of the pickup tube. The color sync signal (NTSC) is know as the color burst.
Sync Compression
The reduction in the amplitude of the sync signal, with respect to the picture signal, occurring between two points of a circuit.
Sync Generator
A device used to supply a common or master sync signal to a system of several cameras. This ensures that their scanning pulses will be in phase. Scanning pulses out of phase produce distortion or rolling, sometimes called "sync loss."
Sync Level
The level of the tips of the synchronizing pulses.
Synchronous Code Division Multiple Access (S-CDMA)
A multiple access physical layer technology in which different transmitters can share a channel simultaneously. The individual transmissions are kept distinct by assigning each transmission an orthogonal "code." Orthogonality is maintained by all transmitters being precisely synchronized with one another. S-CDMA is one of the physical layer technologies included in DOCSIS 2.0.
Synchronous Optical NETwork (SONET)
SONET is an optical interface standard to transport digital signals that allows inter- working of transmission products from multiple vendors. Among other things, it defines optical line rates known as optical carrier (OC) signals; the base rate is 51.84Mbps (OC-1), with higher rates being direct multiples of the base rate. (For example, OC-3 runs at 155.52 Mbps, or three times the rate of OC-1.)
Synchronous Transmission Protocol
A method of encoding a data transmission that does not use start and stop bits at the beginning and end of each byte to synchronize the data time clocks at each end of a connection. Instead it sets its timing signal at the beginning and end of each connection, and corrects discrepancies that arise over time by using the changing values each device on the connection sends and receives to keep their clocks "in sync." Eliminating the start and stop bits reduces the "overhead" required to transmit each byte, and allows for increased throughput.
Syndicated Exclusivity
Requirement by which cable systems must black out significant portions of their distant signals in order to protect syndicated programming offered by local television broadcasters under an exclusive contract. The FCC eliminated this requirement in 1980 and re-imposed it in 1990.
System Integrators (SI)
Companies that provide installation of networking equipment and possibly other services such as training or network management.
System Level
The level of signal in a cable television system at the output of each amplifier. Must be carefully chosen and maintained for least distortion and noise.
System Loss
Cable TV distribution systems are designed to compensate the cable and device losses. The spacing between cable amplifiers can increase as system losses are minimized through the proper choice of connectors, cable and related hardware. System losses are referred to as a "dB of cable" without reference to specific cable size or device losses. Generally these losses are understood to be at the highest operating frequency of the system.
System Noise
Refers to the random energy generated by thermal and shot effects in the system. It is specified in terms of its rms level as measured in a 4-MHz bandwidth centered within a 6-MHz cable television channel.
System Operator
The individual, organization, company or other entity that operates a cable TV system.
System Test Plan (STP)
A plan or policy for verifying system function, performance and/or compliance to a specification.
Systems Management
Functions in the application layer related to the management of various Open Systems Interconnection (OSI) resources and their status across all layers of the OSI architecture.
Systems Network Architecture (SNA)
IBM's layered protocols for mainframe communications.
A type of high-speed digital data connection that operates at 1.54Mbps and requires a two-pair (four-wire) connection between the telephone company Central Office and the customer premises. See also Fractional T-1.
Take Rate
The ratio of homes that pay for a cable service to homes passed.
A tap is a device which splits off a portion of the feeder line signal for the subscriber.
A set rate and service schedule established by agreement between the phone company and a government-run regulatory agency, called the Public Utilities Commission.
T-carrier System
A digital transmission system that takes analog voice circuits and converts them to digital form for transmission using time division multiplexing. The T-0carrier system was designed to operate at different rates, known as T1 (1.544 Mbps, equivalent to 24 channels); T2 (6.312 Mbps, equivalent to 96 channels); T3 (44.736 Mbps, equivalent to 672 channels); and T4 (274.176 Mbps, equivalent to 4,032 channels). (Without compression, a 64-Kpbs channel carries a single voice conversation.) Carrier systems are not always channelized; the entire system can be used to carry high-bandwidth communications.
Television commerce, an interactive television application which enables electronic transactions between businesses and consumers via television.
A term used to describe a picture condition in which groups of horizontal lines are displaced in an irregular manner. Caused by lack of horizontal synchronization.
A local exchange telephone carrier.
Communicating over a distance through wire, radio, optical or other electromagnetic means.
Telecommunications & Internet Protocol Harmonization Over Network (TIPHON)
A project within the European Telecommunications Standards Institute (ETSI) aimed at enabling systems level interoperability for Voice Over IP technologies. ETSI has historically been focused primarily on H.323-based systems; however, they recently have become interested in MGCP-based technologies, such as PacketCable NCS.
Telecommunications Management Network (TMN)
A management concept that defines the relationship between basic network functional building blocks (operations systems, data communications networks, and network elements) in terms of standard interfaces.
Teledensity refers to the number of telephone lines (including wired residential and business lines) per 100 people, a rough measure of the ubiquity of the public switched telephone network (PSTN) in a country.
Telephone Number (TN)
A 10-digit number that specifies the location of a particular telephone and consists of a 3-digit area code, 3-digit central office code, and 4-digit station number.
Broadcast service using several otherwise unused scanning lines (vertical blanking intervals) between frames of TV pictures to transmit information from a central database to receiving television sets.
The electronic transmission and presentation of pictures and sounds.
Television Households
A household having one or more television sets. Estimates for each county are based on an updating of ARB (American Research Bureau) TV penetration estimates. The number of households that watch television in any locality during prime-time hours determines the top 100 markets for FCC cable rules.
Television Market
A city or complex of closely associated cities served by commercial television broadcast signals from one or more TV stations located within the area. The FCC uses television markets for designating what kind of cable services an operator should provide in terms of signal carriage and non-broadcast channel use.
Television Receiver-Only (TVRO)
The receiving antenna dish, or complete package or dish receiver.
A TCP/IP protocol which allows terminal-type login access to computers on the Internet for the purpose of entering remote commands. The protocol name is capitalized; when used in the form "telnet," it refers to the client software that implements the protocol, or the act of using the protocol.
Generally, connection point of equipment, power or signal. Any "terminating" piece of equipment such as computer terminal.
Terminal Endpoint Identifier (TEI)
An unique number that the telephone company switching equipment assigns to each ISDN adapter when it is turned on or connected to a telephone line.
A resistive load for an open coaxial line to eliminate reflections; usually capacitively coupled to avoid shorts in cable-powered systems.
Test Execution Package (TEP)
The actual set of instructions, scripts, results tables, and any other document used to test and report compliance with certain specifications.
Half-inch diameter coax cable.
Thin coaxial cable similar to that used for television/video hookups.
Third Harmonic
A third order beat whose three beating carriers all have the same frequency.
Third Order Beat
An unwanted carrier created by three separate carriers beating against each other. These beating carriers may have the same or different frequencies.
The minimum level at which a signal of any kind can be detected, either by the human senses or by using any electronic instrument.
The speed at which the data is received. Throughput can be increased by compressing data before it is transmitted, then decompressed when it is received, or by using a more efficient transmission protocol.
The 6.25-microsecond time intervals that are the reference for upstream mini-slot definition and upstream transmission times in the DOCSIS protocol.
Ticket Granting Server (TGS)
A sub-system of the KDC used to grant Kerberos tickets.
Tiered Programming
A group of programs for which the customer is charged a fee. For example, most cable systems offer a satellite programming tier.
Supplying cable subscribers with one or more program services beyond the basic offerings at an extra charge. Each additional price increment is called a tier.
Maximum difference in transmission gain of a cable television system over a given bandwidth (typically the entire forward operating frequency range).
Time Division Duplex (TDD)
The method of multiplexing transmit/ receive (uplink/downlink) parts of a wireless communications link together; the exchange of uplink and downlink information takes place on the same frequency, but is distinguished by time-slot characteristics. See also Frequency Division Duplex.
Time Division Multiplexing Access (TDMA)
A multiple access physical layer technology that enables a large number of users to access, in sequence, a single channel without interference by allocating unique time slots to each user within each channel. DOCSIS 1.0, 1.1, and 2.0 use TDMA technology.
Time of Day (ToD)
An internet protocol used by a device to learn the current time from a ToD server.
The character sequence or frame, passed in sequence from node to node, to indicate that the node controlling it has the right to transmit for a given amount of time.
Token Ring
Developed by IBM, this 4 or 16 Mbps network uses a ring topology and a token- passing access method.
Top 100 Market
Ranking of largest television broadcast areas by size of market; i.e., number of viewers and TV households. Used in FCC rulemaking and in selling of airtime to advertisers.
The arrangement of the nodes and connecting hardware that comprises the network. Types include ring, bus, star and tree.
Total Activity Report (TAR)
A quarterly Nielsen report which lists all the television activity during a sweep including broadcast stations, basic cable, pay cable, and superstations. It shows household rating and share delivery by daypart in both the DMA (total market) and cable household universe for all program sources.
A command-prompt utility in MS-DOS and UNIX that reports the gateways, or hops, that your data travels through on the Internet to reach its destination.
Traffic Parameter
A parameter for specifying a particular traffic aspect of a connection.
Transaction Capabilities Application Part (TCAP)
TCAP is a protocol within the signaling system number 7 (SS7) suite of protocols that is used to perform database queries across the SS7 network.
Transaction Language 1 (TL/1 or TL-1)
A management interface protocol defined to configure and manage Telco systems. Telco operations systems support (OSS) providers define this language. The TL-1 provides a specific syntax and it varies from one network element to another vendor.
A combination of a transmitter and a receiver having a common frequency control and usually enclosed in a single package. Extensively used in two-way radio communications at all frequencies.
A device that converts one form of energy or disturbance into another. Transducers convert AC and DC into sound, radio waves, or other forms.
Transient Application
A transient application is an application that must be downloaded before it can be run and may be deleted afterward. Transient applications, such as a program enhancement, are typically delivered via the broadcast system or by request if 2- way functionality is present.
The transfer function of a TIA, the output voltage divided by the input current.
A semiconductor device consisting of three or four layers used for switching or amplification at frequencies ranging from direct current to ultra-high.
Transit Delays
The time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary.
Relay system that picks up distant television signals, converts the signals to another channel to avoid interference, and retransmits them into areas that the original television signal could not reach.
Transmission Amplifier (TIA)
A device used to convert input currents to output voltages.
Transmission Control Protocol (TCP)
A transport-layer Internet protocol which ensures successful end-to-end delivery of data packets without error.
Transmission Control Protocol/Internet Protocol (TCP/IP)
The most common protocol used for communication between computers on a network. Originally developed by the US Department of Defense for a worldwide communications network that eventually developed into the Internet.
Transmission Convergence Sublayer
A sublayer of the physical layer that provides an interface between the data link layer and the physical media dependent (PMD) Sublayer.
Transmission Link
The physical unit of a subnetwork that provides the transmission connection between adjacent nodes.
Transmission Medium
The material on which information signals may be carried; e.g., optical fiber, coaxial cable, and twisted-wire pairs.
Transmission System
The interface and transmission medium through which peer physical layer entities transfer bits.
Transmit Delay
The time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary.
Transmit On/Off Ratio
In multiple-access systems, the ratio between the signal powers sent to line when transmitting and when not transmitting.
The part of a satellite that receives and transmits a signal.
Transport Layer Security (TLS)
An Internet security protocol based on SSL.
Transport Stream
In MPEG-2, a packet-based method of multiplexing one or more digital video and audio streams having one or more independent time bases into a single stream.
A trigger is an event that may cause a change in the behavior of a DVB-HTML application that registers interest in such events. Triggers may come from many sources (for example, the broadcast stream) or may be generated from other data (such as the system clock), or may be generated as a result of user interaction. The trigger may include a reference to time, which may be absolute (UTC), relative to some other event, relative to the NPT of a media stream. It also can carry some semantically significant payload in order to affect changes in an application based on information not available at the time an application was written.
Triple Beat
A third order beat whose three beating carriers all have different frequencies, but are spaced at equal frequency separations.
Trivial File-Transfer Protocol (TFTP)
An Internet protocol for transferring files without the requirement for user names and passwords that is typically used for automatic downloads of data and software.
Tru2way is a CableLabs brand name for an interactive television technology platform. Tru2way includes hardware and software specifications that enable cable hybrid fiber/coax networks to deliver interactive applications such as electronic program guides, interactive ads, games, chat, web browsing, and t-commerce. The brand also appears as <tru2way> and is used to market cable services, applications, and devices that support the tru2way architecture. A cable television subscriber who has an integrated digital television (DTV) that supports tru2way can enjoy the same features as those delivered by way of the cable provider's leased set-top box (STB), without the STB.
An analog or digital connection from a circuit switch which carries user media content and may carry telephony signaling (MF, R2, etc.). Digital trunks may be transported and may appear at the Media Gateway as channels within a framed bit stream. Trunks are typically provisioned in groups, each member of which provides equivalent routing and service.
Trunk Amplifiers
The amplifiers along the trunk line responsible for maintaining signal strength must have low distortion, low noise, and moderate gain. Degradation of the signal along the trunk cannot be corrected downstream, in fact, cascade amplifiers with similar faults simply amplify the fault too. Trunk amplifiers compensate for cable losses with automatic slope control (ASC) and automatic gain control (AGC).
Trunk Cable
Cables that carry the signal from the headend to groups of subscribers. The cables can be either coaxial or fiber depending on the design of the system.
Trunk Circuit
A circuit, part of a switching system, associated with the connection of a trunk to the switching system. It serves to convert between the signal formats used internally in the switching system and those used in the transmission circuit, and it performs logic and sometimes memory functions associated with supervisors.
Trunk Line
The major distribution cable used in cable television. It divides into feeder lines which are tapped for service to subscribers.
Transporting signals from one point (an antenna site for instance) to another point (such as a headend), usually without serving customers directly. Trunking can be accomplished using coaxial cable, fiber optics or microwave radio.
Tunnel Mode
An IPsec (ESP or AH) mode that is applied to an IP tunnel, where an outer IP packet header (of an intermediate destination) is added on top of the original, inner IP header. In this case, the ESP or AH transform treats the inner IP header as if it were part of the packet payload. When the packet reaches the intermediate destination, the tunnel terminates and both the outer IP packet header and the IPsec ESP or AH transform are taken out.
TV Penetration
The percentage of homes having one or more television sets at the time of the ARB (American Research Bureau) survey. The ARB surveys local markets from October through July; the number of surveys in a year depends on the size of the market.
Twisted Pair
A pair of wires used in transmission circuits and twisted about one another to minimize coupling with other circuits. Paired cable is made up of a few to several thousand twisted pairs.
Bidirectional communications over the same communication medium.
Two-way Capacity
A cable television system with two-way capacity can conduct signals to the headend as well as away from it. Two-way or bi-directional systems now carry data; they may eventually carry full audio and video television signals in either direction.
Two-way System
The ability to receive TV programming through the broadband network and send information back through the same network. This capability is used by customers to order movies and music and to interact in other manners with the Broadband network.
Type of Service (ToS or TOS)
A field within an IP packet that can be used to request priority treatment of the packet by the network. The ToS field and mechanism have been replaced by Differentiated Services (DiffServ) and DiffServ Codepoints (DSCPs).
Type/Length/Value (TLV)
An encoding of three fields, in which the first field indicates the type of element, the second the length of the element, and the third field the value.
Typical Operating Conditions
Optimum operating conditions for a stated number of channels.
Ultra High Frequency (UHF)
Channels above channel 13 (or from 470 MHz to 806 MHz).
Unbound application
An unbound application is not associated with a broadcast service.
The separation and discrete offering of the components of the local telephone service. Unbundling of network components facilitates the provision of pieces of the local network, such as local switching and transport, by telephone company competitors.
Unidirectional Hypertext Transport Protocol (UHTTP)
A broadcast transfer protocol, suitable for delivery of content using IP multicast.
Uniform Resource Locator (URL)
The address of an Internet site. The URL contains the protocol used for the site (e.g., http, ftp), the domain name or IP address of the site (e.g., and, optionally, the folder or page on the site where specific information is stored.
Universal Asynchronous Receiver Transmitter (UART)
A computer's UART chip dictates the maximum rate a computer can send and receive data over its serial ports.
Universal Serial Bus (USB)
A plug-n-play standard for connecting multiple (up to 127) input/output devices to a single high-bandwidth port. The design of the bus allows hot-swapping of the devices (disconnection and reconnection without powering the computer off) and automatic configuration. The USB peripheral bus standard was developed by Compaq, IBM, DEC, Intel, Microsoft, NEC, and Northern Telecom. The original version of USB (USB1.1) supports a data rate of 12Mbps, while the second version (USB2.0) supports a data rate of 480 Mbps.
Unspecified Bit Rate (UBR)
The UBR service class is intended for delay-tolerant or non-real-time applications, or those which do not require tightly constrained delay and delay variation.
A device used to add a lower frequency to a microwave frequency.
The return signal from the user to the base station.
The transfer of files from a local computer "up" to a remote computer.
The term used to describe traffic and paths that go from the subscriber to the headend. Also known as Reverse Path or Return Path.
Upstream Channel Descriptor (UCD)
The MAC Management Message used to communicate the characteristics of the upstream physical layer to the cable modems.
User Agent
A native or OCAP�-based application running on a set-top receiver that decodes and executes a binary-encoded enhanced television application.
User Datagram Protocol (UDP)
A protocol residing on top of IP that is used for end-to-end transmission of user messages. Unlike TCP, UDP is an unreliable protocol, which means that it does not contain any retransmission mechanisms. Thus, UDP packets are not guaranteed to make it through the network.
User Interface (UI)
A user interface is the sensory and behavioral aspects of a program that are presented to a user. The term is generally used to denote the menuing and navigational constructs of a program.
Value-Added Reseller (VAR)
Refers to distributors that also provide other services such as systems integration or network management.
Variable Bit Rate (VBR)
A type of telecommunications service characterized by a service bit rate specified by statistically expressed parameters that allow the bit rate to vary within defined limits.
Very high-speed digital subscriber line that utilizes existing copper infrastructure of the telephone companies. VDSL offers video and data transmission rates up to 52 Mbps up to 2,700 feet. See also DSL.
Velocity of Propagation
Velocity of signal transmission. In free space, electromagnetic waves travel with the speed of light. In coaxial cables, this speed is reduced. Commonly expressed as percentage of the speed in free space.
Vertical Blanking Interval (VBI)
A portion of the television signal that does not contain visual data. In NTSC, the VBI are lines 1 through 21 in each field.
Very High Frequency (VHF)
Channels 2-13 (54-88 MHz and 174-216 MHz).
Very Small Aperture Terminal (VSAT)
Small earth stations with a satellite dish usually 4-6 feet in diameter used to receive high speed data transmissions; can also transmit slow-speed data.
Vestigial Sideband Transmission
A system of transmission wherein the sideband on one side of the carrier is transmitted only in part.
A term pertaining to the bandwidth and spectrum of the signal which results from television scanning and which is used to produce a picture.
Video Band
The frequency band utilized to transmit a composite video signal.
Video Transmission
The original video signal before it is modulated and converted to radio-frequency and broadcast or cablecast. A home television set reconverts radio-frequencies to a video signal.
Video-on-Demand (VOD)
Allows the end-user subscriber to select at any time movies they wish to view from a large selection of titles and categories stored on a remote server. Service may also provide VCR functionality, (stop, pause, etc.) which allows the end-user subscriber to control the "play back" of the server from the remote control. Or a television service where viewers can select and watch video content for viewing at any time.
Used to electronically record sight and sound for instant playback. Videotape comes in half-inch, three-quarters, one and two-inch widths and can be erased and re-recorded.
Videotape Recorder (VTR)
A device which allows the recording and playback of magnetic tape sound and picture recordings.
The generic term used to refer to a two-way interactive system for the delivery of computer-generated data into the home, usually using the television set as a display device. Some of the more often used specific terms are "viewdata" for telephone-based systems (narrowband interactive systems); "wideband broadcast" or "cabletext" for systems utilizing a full video channel for information transmission; and "wideband two-way teletext" for systems which could be implemented over two-way cable television systems. In addition, hybrids and other transmission technologies, such as satellite, could be used for delivery of videotex services on a national scale.
Viewers Per Viewing Household (VPVH)
A demographic percentage which indicates how many persons per 100 or per 1,000 households are viewing. For example, a VPVH of 80 K2-11 means that for every 100 households viewing, there are an estimated 80 children ages 2 to 11.
Violence Chip (V-Chip)
A term used to describe a microchip which will permit parental control over rated television programs.
Virtual Channel (VC)
The communication channel that provides for the sequential unidirectional transport of ATM cells.
Virtual Channel Table (VCT)
Data declared as part of the Service Information standard defined by SCTE.
Virtual Ccircuit
This term refers to a predefined path through a network that provides a connection-oriented session between two applications.
Virtual Private Network (VPN)
A term that is applied to either voice or data networking. In essence, a VPN is a portion of a public network that has been logically partitioned for private use.
Voice Activation Detection (VAD)
Allows a data network carrying voice traffic to detect the absence of audio and conserve bandwidth by preventing the transmission of "silent packets" over the network. Most conversations include about 50% silence. VAD is also called "silence suppression".
Voice-over-Internet Protocol (VoIP)
VoIP services are a provision of voice telephony via the use of packet-switched networks running Internet Protocol (IP) networks rather than traditional circuit switching. CableLabs has developed the PacketCable specifications for the delivery of IP-based multimedia services, including voice services, over the DOCSIS 1.1 access network.
Voice-Over-Net (VON)
A term that refers to various sets of technologies that are used to enable voice applications across the Internet.
A graphical representation of the rise and fall of the electrical potential (voltage) on a pair of wires or some other signal over time. A classic example of a waveform is the spiky line displayed on a cardiograph machine used to analyze the electrical activity created as the heart beats. In telephony, analog waveforms are translated into a series of binary values, called samples. These samples are taken 8,000 times a second, sent on to their destination, where they are translated back into a series of 8,000 changes in voltage that almost resembles the original analog signal.
Wavelength Division Multiplexing (WDM)
Technology that enables the capacity of fiber-optic lines to be increased exponentially through the use of different frequencies (or colors). As more colors are utilized, more unique communication paths are created.
Web Page
An HTML document accessible on the World Wide Web using a Web browser.
Wide Area Network (WAN)
A computer network which usually spans larger geographic area, such as cities, counties, states, nations and planets. WAN's usually employ telephone-type topologies, like T1, T2, T5, ATM, etc. The Internet is a WAN which is held together by LANs, which network computers.
Wide Area Telecommunications Service (WATS)
WATS permits customers to make (OUTWATS) or receive (INWATS) long distance voice or data calls and to have them billed on a bulk rather than individual call basis. The service is provided within selected service areas, or bands, by means of special private-access lines connected to the public telephone network via WATS-equipped central offices. A single access line permits inward or outward service, but not both.
Typically, the term wideband represents a medium intermediate between narrowband and broadband. Wideband is capable of transmitting at more than 64 Kbps and less than 1.5 Mbps.
Windows Media Digital Rights Management (WMDRM)
Microsoft's DRM solution.
Windshield Wiper Effect
Onset of overload in multichannel cable television systems caused by cross-modulation, where the horizontal sync pulses of one or more TV channels are superimposed on the desired channel carrier. Both black and white windshield wiping are observed and are caused by different mechanisms.
Wired City
The concept of television and other communications data, educational material, instructional television and information retrieval service that wired services can provide. Broadcast services must, of necessity, be limited by scarce spectrum space; wired services have theoretically unlimited channel capacity.
Wireless Cable
Uses microwaves frequencies to transmit programming to a small antenna at a subscriber's home.
Wireless Local Loop
In conventional wired systems, the local loop refers to the connection that runs from the subscriber's telephone set, PBX or telephone system to the telephone company's central office (CO). As the name implies, a WLL connects potential users to the CO by substituting a wireless base station for the local-loop connection. WLL service is the most advantageous alternative for parts of the world that can leapfrog expensive and time-consuming wire installations in establishing modern telecommunications systems.
World Wide Web (WWW)
The name given to all HTML documents which exist on all of the interconnected HTTP servers around the world. Originally developed in 1989 for the European Laboratory for Particle Physics to enable its users to share documents in a more graphical fashion.
X.509 Certificate
A public key certificate specification developed as part of the ITU-T X.500 standards directory.
Extended Application Information Table. Used for launching and managing the lifecycle of unbound applications.
The general term applied to a whole family of high-speed digital data products. The letters DSL stand for Digital Subscriber Line. The x is a place keeper for the term describing the type of DSL connection: A for Asymmetric, H for High Speed, I for ISDN, S for Symmetric. These new technologies, ADSL, HDSL, IDSL, and SDSL are expected to be the next-generation high-speed data products that will someday replace existing technologies like ISDN and Fractional T-1 lines.
Xlet is the interface used for execution engine application lifecycle control.
Zero Cells
A phenomenon common to local market cable television ratings. The Nielsen household meter indicates viewing, but the corresponding diary data shows no record of viewing.