100Base-T
One of the more common types of Ethernet LAN cabling. Specifies 100 Mbps (baseband) carried over twisted pair. Also known as Fast Ethernet.

1000Base-T
One of the more common types of Ethernet LAN cabling. Specifies 1000 Mbps (baseband) carried over twisted pair. Also known as Gigabit Ethernet or GigE.

2B1Q
Short for 2 Binary, 1 Quaternary. 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, quaternary voltage that indicates both ends of the data connection are sending the same binary value.

56 Kbps Modems
More appropriately called PCM 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 33.6 Kbps. 56Kbps modems are built against the ITU-T V.90 or V.92 standards.

AAFES
Army and Air Force Exchange Service - TKS partner and main shopping outlet for U.S. Military service and family members.

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

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

Acceptance Test Plan (ATP)
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 for 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 MAC protocol for access onto the Access Network; separating or classifying traffic prior to multiplexing onto the Transport Network-such as differentiating traffic that is subject to QoS guarantees from traffic that receives best-effort support; enforcing signaling; handling passive operations such as splitting and filtering.

Activation fee
One-time charge. This may be seen as administrative or start-up cost. Also see, Initial fee.

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

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

Active Service Flow
An admitted Service Flow from the CM to the CMTS which is available for packet transmission.

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

Adaptive smart antenna
Combines multiple antenna elements with signal processing algorithms to optimize its radiation and/or reception pattern automatically in response to the signal environment.

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

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

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

Adjacent Channel
Any of two TV channels are considered adjacent when their view carriers, either off-air or on a cable system, are 6 MHz apart. FM signals on a cable system, two channels apart are adjacent when their carriers are 400 to 600 kHz apart.

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

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

Adaptive Timeout
Retry with exponential timeout. First attempt - 1 second and the last attempt - 16 seconds.

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

AktivPlus
Add on tariff for discount calling rates.

A-link
A-Links are SS7 links that interconnect STPs and either SSPs or SCPs. 'A' stands for "Access."

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

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.

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

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

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

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

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

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

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

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

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

Antenna Stack
Antenna tower with multiple antennas and supports.

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

Application form
The actual form to be filled out to request service.

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

Asymmetric Digital Subscriber Line (ADSL)
ADSL is a data communications technology that can "piggyback" a standard voice telephone connection and a high-speed (up to 8Mbps) digital data link on to a single pair local loop connections to a customer premises. ADSL technology is an asymmetric technology, meaning that the speed of the digital link to a customer premises is generally not the same speed as the connection coming back. With ADSL, for example, a customer may have only 128Kbps of outbound bandwidth, but may be able to receive data at speeds of 8Mbps. See DSLAM, NID, and xDSL, cable modem.

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

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

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

Asynchronous Transmission Protocol
A method of encoding a data transmission that places start and stop sequences at the beginning and end of each byte, instead of at the beginning and end of each larger block of data sent. This increases the "overhead" required to transmit each byte and decreases throughput. See also Synchronous Transmission Protocol.

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

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

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

Automatic Debit Transfer (Direct Debit)
Customer allows TKS to extract owed moneys from customer bank account. Customer is protected by law from possible misuse. Customer may recall any outgoing moneys up to 6 weeks after transaction without any accruing financial penalties.

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.

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.

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

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

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

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

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

Availability
In cable television systems, availability is the long-term ratio of the actual radio frequency (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.

Backus Naur Form (BNF)
A formal notation used to define the syntax of a language.

Backbone
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.

Bandwidth
(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 30,720,000 bits-per-second (30.72 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 CMTS uses to allocate transmission opportunities to CMs.

Basic monthly fee
Standard monthly charge owed for service received, or to be received.

Baseband
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.

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.

Basic Cable
The basic program services distributed by a cable provider 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.

Binder
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 fun 4, 6, or 8 pair cables to each desktop to provide telephone and computer network connections.

Bit
(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. This is the smallest stored unit of data.

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.

Bonding/Bundling
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.

Bookmarks
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 messages as defined in [ISO/IEC10038].

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.

Broadband
A transmission medium which 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.

Broadcaster's Service Area
Geographical area encompassed by a station's signal.

Broadcasting
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.

Broadcast
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 head end 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.

Brouter
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.

Browser
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.

Building Number
Facility number assigned to building on-base/post.

Bundling/Bonding
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.

Burst Error Second
Any errored second containing at least 100 errors.

Bus
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.

Byte
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. TKS customer needs this piece of actual hardware for TKS Internet access via TKS CableModem Service.

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 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 Network
TKS Cable Network has a frequency range 47-862 MHz. It has a network capability of more than 60 analog channels and significantly greater potential for digital programs.

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 (CATV) 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 band 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.

Cablecasting
To originate programming over a cable system. Includes public access programming.

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.

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.

Cancellation/s
Termination of service at customer's request

Carriage
A cable system's procedure of carrying the signals of television stations on its various channels.

Carrier
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-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.)

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.

Cartridge
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. colour, 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).

CashCards
Coded cards for uploading money/credit to pre-paid phone.

Cassette
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.

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

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

CCI
See Copy Control Information

CCCM
See CPE Controlled Cable Modem

CM
Cable Modem

CMTS
Cable Modem Termination System

CNT
Coaxial Network Terminal

Cell
ATM layer protocol data unit.

Cellular
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.

Channel
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.

Cipher
An algorithm that transforms data between plaintext and ciphertext.

Ciphertext
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 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.

Classifier
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.

Cleartext
The original (unencrypted) state of a message or data. Also called plaintext.

Clipping
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.

Cluster
The group of homes passed by a single fiber node.

Clustering
Grouping together of independent cable systems into a larger, more efficient single system that utilizes some of the same infrastructure.

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.

Coaxial Network Terminal (CNT)

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 Codec.

Collision
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 3.6 MHz 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)

Combiner
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.

Commanders Info Channel
Channel provided by TKS for local U.S. Military commanders to issue information to their communities, usually administered by local PR office

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 company (ALT). 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-linearity's in cable system equipment.

Composite Triple Beat (CTB)
The peak of the average level of distortion components due to third-order non-linearity's 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.

Compression
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.

Confidentiality
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.

Consolidated Mail Room
U.S. Military mail room open to all service and family members

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
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.

Contract
Legal document accepted and signed by 2 parties.

Contract Application
Request for services, signed only by applicant. This becomes a contract when service is actually connected (considered just as a 2 party signature)

Contrast
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.

Converter
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.

Cookies
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.

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.

Crosstalk
Noise passed between communications cables or device elements.

Cryptanalysis
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.

CSR
Customer service representative.

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.

CTAN
Cable Telephony Access Note

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.

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 their 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.

DTAG (Deutsche Telekom AG)
Largest Telecommunications provider in Germany.

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.

DAVE tap
Acronym: Daten Verwaltungs Einheit - a remate device to control connections and disconnections of Cable TV service.

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.

Decipherment
A procedure applied to ciphertext to translate it into plain text.

Decryption
A procedure applied to ciphertext to translate it into plaintext.

Decryption key
The key in the cryptographic algorithm to translate the ciphertext to plaintext.

Delay
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.

Demographics
Breakdown of television viewers by such factors as age, sex, income levels, education and race.

Demodulation
The extraction of the modulation or information from a radio-frequency current.

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.

Descrambler
An electronic circuit that restores a scrambled video signal to its standard form.

Detector
The photodiode in optical receivers.

Deutsche Industrie Norm (DIN)
German Industrial Standards

Deutsche Telekom AG (DTAG)
Largest telecommunication provider in Germany.

Dial-up
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.

Digital
(1) In communications and computer technology, digital refers to a method of encoding information using a binary system made up of zeroes and ones. In communications technology this takes the form of two very different electrical voltages, several volts positive and negative, to represent the two values. This substantial difference in voltages for each state makes it unlikely that minor fluctuations in voltage due to electro-magnetic interference will change the way a signal is interpreted when received. (2) 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 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 pan European 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 MPEG program (typically a commercial) into another based on digital 'cues' within the MPEG transport stream.

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

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 PVR.

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-multi-point" 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.

DirectX
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.

Disconnection/s
Refers to disconnection of customer(s) due to non-payment for cable TV service.

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.

Distortion
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.

DOCSIS 1.0
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.

DOCSIS 1.1
The second version of the DOCSIS protocol standard. 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.

DOCSIS 2.0
The third version of the DOCSIS protocol standard, 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.

DOCSIS Radio Frequency Interface (RFI) Specification
Radio-frequency interface specifications for high-speed data-over-cable systems.

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.

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 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 signalling indicates which services can load an application and which services allow an already active application to continue.

Domain Name Server (DNS)
A server that relates an internet domain name (such as www.tkscable.com) to an IP address.

Double-Click
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.

Downlink
Transmission of signals from a satellite to a dish or earth station.

Download
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.

Downstream
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.

Drop
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.

Duplex
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
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
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.

Easement
The right to use land for a specific purpose, such as laying cable.

EBITDA
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.

EBITA
Earnings before interest, taxes and amortization. Similar to EBITDA, but is reduced to give effect to periodic depreciation expenses.

Echo
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. 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 Frequency.

Electronic Commerce (E-Commerce)
Used to describe commerce that occurs electronically over the Internet.

Element Management System (EMS)
That contains software applications used for configuration, performance, and faults from one or more network elements. The EMS 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.

Email
The electronic exchange of messages and files between computers on a network, email is the abbreviated form of electronic mail. An e-mail client is usually integrated with popular browsers.

Embedded-Client
A synonym for, and equivalent with, "Embedded Subscriber Media Gateway."

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).

EN
European Norms. Prefix for certain ETSI documents.

Encipherment
A method used to translate plaintext into ciphertext.

Encryption
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.

Ending Termination of Service
Date of out processing of U.S. military service.

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.

Endpoint
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.

Equal Access
The offering of access to local exchange facilities on a non-discriminatory basis.

Equalization
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.

Ethernet
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.

Euro
European currency accepted throughout European Community including Germany

European Community
All European countries. European Community (EC), established-8 April 1965 . The aim of this union was to integrate the European Atomic. This took effect July of 1967 . Former members of this community consisting of the following 12 members: Belgium, Denmark, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, UK. This community is known known as the European Unit.

ETS
European Telecommunications Standard. Prefix for certain 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.

Exclusivity
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.

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.

F-Connector
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.

F-Link
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."

Facsimile
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.

Fading
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.

Favorites
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.

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.

Field
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").

Filter
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.

Flat Outputs
Operation of a cable television system with equal levels of all TV signals at the output of each amplifier.

Flat Rate
Standard charge (monthly) without user limitations.

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 Error Correction (FEC)-FEC enables the receiver to detect and fix errors to packets without the need for the transmitter to retransmit packets.

Forward Channel
The direction of radio frequency (RF) signal flow away from the headend toward the end user; equivalent to downstream.

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.

Fragmentation
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.

Frame
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.

Franchise
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.

Frequency
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.

Frequently Asked Questions (FAQ)
These are frequently asked questions usually assembled as inquiries in a quick-reference list

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 Half Duplex.

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.

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.

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 also is admirably suited to the fully automated cable television system concept.

Function
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.

Gain
A measure of amplification expressed in dB. Gain of an amplifier is usually specified at the highest frequency of operation.

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.

Ghost
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.

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

Half Duplex
Two-way transmission, one way at a time.

Halo
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.

Handy
German slang and widely accepted business term for describing the American cell phone service and wireless mobile communication.

Hardware
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

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.

Headend Station
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.

Header
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.

Heterodyne
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-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 LDC 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 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.

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 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.

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.

House Drop
The coaxial cable that connects each building or home to the nearest feeder line of the cable network.

House Number
Designates off-base/post address (German address)

Hub
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.

Hue
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.

IEEE-1394
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.

IC
A communications common carrier that provides telecommunications services between LATAs or between exchanges within the same LATA.

Impedance
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.

Independent
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.

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

Inductor
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.

Infomercial
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.

InfoKabel
Commanders Info Channel

Initial fee
One-time charge. This may be for administrative expenses or start-up cost.

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.

Installation Fee
One-time charge for installed equipment in customer's quarters

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.

Integrity
A way to ensure that information is not modified except by those who are authorized to do so.

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 email 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."

Interchangeability
The ability to exchange tapes between different manufacturers' videotape recorders with no appreciable degradation of playback image.

Interconnect
Two or more cable systems distributing a programming or commercial signal simultaneously.

Interdiction
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.

Interference
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.

Interlacing
The television display format, where horizontal lines of pixels are illuminated in an alternating pattern rather than sequentially.

Intermodulation
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.

Internet
Also known as the World Wide Web. 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.

Interval Usage Code
A field in MAPs and UCDs to link burst profiles to grants.

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., 24.64.231.1). 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).

IPCONFIG
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.

ISDN
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 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. Jitter-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.

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

Keys
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.

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 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.

Keyspace
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
A unit of measurement ; 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."

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

Laser
A device that generates coherent electromagnetic radiation in, or near, the visible part of the spectrum.

Latency
The time taken for a signal element to pass through a device or system.

Layer
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.

Leaseback
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.

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 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 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 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 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 email. 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 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.

Locator
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 schemed 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 (FTP, others?) may use the return channel. This version of the specification does not include a scheme for transport 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 sub layer 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 Logical Link Control Procedure.

Logical Link Control (LLC) 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.

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.

Luminance Signal
That portion of the NTSC color television signal which contains the luminance or brightness information.

Mahnung
Bill reminder

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.

Man-Machine Interface (MMI)
Another term for User Interface.

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.

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 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 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 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.