Telecommunications Glossary from “A Technical Guide to Teleconferencing and Distance Learning,” 3rd edition


A fee charged subscribers or other telephone companies by a local exchange carrier for the use of its local exchange networks.
A signaling method that uses continuous changes in the amplitude or frequency of a radio transmission to convey information.

Access Channels Dedicated channels giving nondiscriminatory access to a local
cable system by the public, government agencies or educational institutions
ACCUNET Switched Digital Services High-speed dial-up digital data services offered
by AT&T for full duplex digital transmission at speeds of 56, 64, 384 and 1536 kbps.
Uses include data, voice and video services
Acoustic Coupler A device that allows a conventional telephone handset to feed its
signal into a modem, as opposed to direct couplers, which feed the
modulated/demodulated signal directly into the phone line
Acoustic Echo Canceller All speakerphones have some form of adaptive echo
canceller that produces a synthetic replica of the potential echo to subtract from the
transmit audio. Most units have a center clipping echo suppresser to remove the
residual echo from the transmit signal. The goal of the acoustic echo canceller is to
reduce the amount of direct and reverberant loudspeaker coupling to the microphone to
prevent echo. To achieve this, the algorithms used in today's devices require an audio
system that is feedback stable
Acoustic Echo Return Loss - AERL The minimum loss experienced by a sound in
traveling from the loudspeaker to the microphone in a conference room. It is expressed
in dB or decibels. A 0 dB loss corresponds to a perfectly reflective room or to very close
coupling between loudspeaker and microphone. In practice, AERL figures can range
from 0 to -30 dB, with a poor room having the former figure
Acoustic Echo Return Loss Enhancement - AERLE The maximum echo
cancellation provided by the acoustic canceller. Typical figures will vary from 6 to 18 dB.
The larger the number the better. It is important to note whether the figure is quoted with
the center clipper enabled or disabled. If quoted with center clipper disabled, it is a true
measure of the cancellation provided by the echo canceller rather than the attenuation
provided by the center clipper.
Acoustic ModemA modulator-demodulator unit that converts data signals to
telephone tones and back again
Active Satellite A satellite that transmits a signal, in contrast to a passive satellite that
only reflects a signal. The signal received by the active satellite is usually amplified and
translated to a different frequency before it is retransmitted
Ad Hoc Teleconferencing technology and sites assembled for an event; equipment
may be rented or permanently installed; sites are not always part of the network
Addressable The ability to signal from the headend or hub site in such a way that only
the desired subscriber's receiving equipment is affected. This makes it possible to send
a signal to a subscriber and effect changes in the subscriber's level of service such as
the ability to receive a program
ADPCM - Adaptive differential pulse code modulation A method of compressing audio data by recording the differences between successive digital samples rather than full value of the samples. There are many different types of ADPCM standards; this refers to the standard as defined in the CD-ROM XA and CD-I standards
ADSL - Asymmetric Digital Subscriber LoopADSL uses a regular phone line
(twisted pair) without a dial tone (a dry pair) to allow transfer speeds of up to 7Mb
downstream with slower speeds going back up (faster than a T1). The Telcos are using
ADSL to maintain market share rather than allowing the cable industry to deploy cable
modems. Pacific Bells says that 45 percent of its customers will be able to have access
to ADSL by the end of 1997
Affiliate Network Group with their own satellite receive equipment; routinely receive same programming
AgentSee knowbot
Algorithm 1. Rule of thumb for doing something with a semblance of intelligence. For example, a descrambling algorithm will yield a clear, unscrambled message from an apparently meaningless one. 2. The procedure used for performing a task
America Online - AOLCommercial information service with a graphical interface
Amplifier A device used to increase the strength of video and audio electronic signals
Amplitude The size or magnitude of a voltage or current waveform; the strength of a signal
AnalogInformation represented by a continuous electromagnetic wave encoded so that its power varies continuously with the power of a signal received from a sound or light source
Analog-to-Digital - A/D ConversionThe conversion of an analog signal into a digital
equivalent. An A/D converter samples or measures an input voltage and outputs a
digitally encoded number corresponding to that voltage
Analog TransmissionTransmission of a continuously variable signal as opposed to a discrete signal. Physical quantities such as temperature are described as analog while
data characters are coded in discrete pulses and are referred to as digital.
AnimateTo effect motion of any sort; e.g. to animate a person's presentation
AnimationA video, film, and computer production technique utilizing cartoon-type artwork to create the illusion of movement
ANSI - American National Standards Institute ANSI is one of these "terminal
emulation" methods. Although most popular on PC-based bulletin-board systems, it can
also be found on some Internet sites. To use it properly, you will first have to turn it on,
or enable it, in your communications software
AnswerbackThe response of a terminal to remote control signals. Antenna (dish) The
device that sends and/or receives signals (electromagnetic) from the satellite
Antenna PowerThe product of the square of the broadcast antenna current and the antenna resistance where the current is measured
ApertureA cross section of the antenna exposed to the satellite signal
Application The use of a technology to achieve a specific objective
Application Software In computers, programs used to interact with and accomplish
work for the user. Application software is usually written in a higher computer language
such as Basic, COBOL, FORTRAN or Pascal, and may be written by the user or
supplied by the manufacturer or a software company
Applications ProgramA computer program dedicated to a specific purpose or task. Applications programs which produce discernible results and can sometimes be machine-independent, are distinct from systems programs, which are designed to drive particular electronic devices and are always machine dependent
Archie A system which allows searching of indexes of files available on public servers on the Internet
ArchivalA medium that is readable and/or writable for an extended period
Armored Cable Coaxial cable that can be direct buried without protective conduit, or used in underwater applications
ARPANet A predecessor of the Internet. Started in 1969 with funds from the Defense Department's Advanced Research Projects Agency
ASCII American Standard Code for Information Interchange; pronounced "Askee." An eight-level code for data transfer adopted by the American Standards Association to achieve compatibility between data services
Aspect RatioThe ratio of picture width to height (4 to 3 for North American NTSC broadcast video)
Asynchronous CommunicationTakes place in different time frames and accessed at the user's convenience. Synchronous communication takes place in the same time frame such as a live teleconference
Asynchronous Time-Division Multiplexing An asynchronous signal transmission mode that makes use of time-division multiplexing
Asynchronous Transmission A technique in which the time interval between
characters may be of unequal length. Transmission is controlled by start and stop elements at the end of each character. Used for low-speed terminal links
ATM - Asynchronous Transfer ModeATM switching protocol can handle all types of
traffic - voice, data, image, and video
AttenuationThe difference between transmitted and received power due to loss through equipment, lines, or other transmission devices; usually expressed in decibels. The loss in power of electromagnetic signals between transmission and reception points
Attenuator A device for reducing the amplitude of a signal
ATSCAdvanced Television Systems Committee
ATV - Advanced TelevisionAn agglomeration of techniques, based largely on digital signal processing and transmission, that permits far more program material to be carried through channels than existing analog systems can manage. In this sense, HDTV (high definition television) is a subset of ATV. ATV does not automatically signify improved picture or sound performance. Those are things that can be accomplished with ATV in systems designed for such purposes, but it can also carry ten somewhat
lower- quality signals where only one could exist previously, or permit ghost cancellation for ordinary NTSC signals. In each case, the new features derive from the use of digital techniques of one form or another
Audio Bridge An audio bridge connects the telephones at remote sites, equalizes the noise distortion and background noise for a live audio teleconference
Audio FrequencyA frequency lying within the audible spectrum (the band of frequencies extending from about 20 Hz to 20 kHz)
Audio PresentationOften overlooked, but just as important as the video (perhaps more so) is the sound portion of the program. Without the audio, nothing is understood while a video failure could be tolerated if the sound portion is not affected. Use a good audio system to augment the video display. Do not use the built-in speaker of the TV monitor or room PA system. Rather, employ a high quality stand-alone system, with the speakers positioned adjacent to the TV screen. This affords the best audio experience. The audio quality coming off the satellite signal is true high fidelity, and its reproduction further enhances program presentation
Audio TeleconferencingTwo-way electronic voice communication between two or more groups, or three or more individuals, who are in separate locations
AudiographicTeleconference system which uses narrow band telecommunications
channels (telephone lines or subcarriers); transmits audio and graphics. Graphics can
be transmitted by facsimile transceivers (transmitter-receiver), computers (text or
graphic display), or electronic drawing systems (such as electronic blackboard) which
allow a participant to draw or write on an electronic screen which is transmitted to a remote site where participants can see it
Audio Response A form of output that uses verbal replies to inquiries. The computer is programmed to seek answers to inquiries made on a time-shared on-line system and then to utilize a special audio response unit which elicits the appropriate prerecorded response to the inquiry
Audio Response Unit Device that provides a spoken response to digital inquiries from
a telephone or other device. The response is composed from a prerecorded vocabulary
of words and can be transmitted over telecommunication lines to the location from which the inquiry originated
Audio-SubcarrierFrequency which transmits audio for an ccompanying video signal or independent audio (such as a radio program). Audio is sent along with the video signal, but on a different frequency
Aural CableServices providing FM-only original programming to cable systems on a lease basis
Authoring System Computer software that allows one to develop the framework for an
interactive multimedia presentation. Authoring software enables the use of multiple data
types as well as the controls needed to play-back information on the computer from devices such as CD-ROMs, computer hard disks and videodiscs
Automatic Number Identification - ANIThe automatic identification of a calling
station, usually for automatic message accounting. Also used in pay-per-view
automated telephone order entry to identify a customer for billing and program
authorization purposes
Azimuth Angle between an antenna beam and the meridian plane, measured along a horizontal plane. How far east or west in the southerly sky the satellite is located in relation to the local meridian, or north-south plane. It is measured in degrees, clockwise from true north


BANDWIDTHThe capacity of a telecom line to carry signals. The necessary bandwidth is the amount of spectrum required to transmit the signal without distortion or loss of information. FCC rules require suppression of the signal outside the band to prevent interference.
Broadband is a descriptive term for evolving digital technologies that provide consumers a signal switched facility offering integrated access to voice, high-speed data service, video-demand services, and interactive delivery services.
B-Mac A method of transmitting and scrambling television signals where MAC (multiplexed analog component) signals are time-multiplexed with a digital burst containing digitized sound, video synchronizing, authorization, and information.
BackboneA high-speed network that connects several powerful computers. In the
U.S., the backbone of the Internet is often the NSFNet, a government funded link
between a handful of supercomputer sites across the country.
Backbone Microwave SystemA series of directional microwave paths carrying common information to be relayed between remote points. The backbone microwave system is engineered to allow the insertion of signals, the dropping off of signals and the switching of signals along its length at designated relay points. In order to maintain the signals in the highest possible quality, the equipment used in the backbone microwave system is normally of a higher technical performance level than other microwave electronics in the network. Antennas are always directional.
Backhaul A term used for the transmission of a signal (normally video) from the ends of transmission systems such as microwave to a central point. For a satellite videoconference, a backhaul refers to a signal brought in from a secondary site to the origination site, mixed with the primary signal, and sent out over the program out
Bandwidth Determines the rate at which information can be transmitted across that a
medium. The rates are measured in bits (bps), kilobits (kbps), megabits (Mbps), or
gigabits per second (Gbps). Typical transmission services are 64 kbps, 1.544 mbps (T1), and 45 Mbps (T3). The space between the top and bottom limit of airwave frequencies that are transmitted over a communications channel. The maximum frequency (range), measured in Hertz, between the two limiting frequencies of a transmission channel; the range of frequencies that can be carried by a transmission medium without undue distortion. Narrowband uses lower frequency signals such as telephone frequencies of about 3,000 Hertz and radio subcarrier signals of about 15,000 Hertz. Broadband uses a wide range of frequencies (broadcast and cable TV, microwave and satellite; carries a great deal of information in a short time; more expensive to use. C band is in the 4 to 6 giga-Hertz (gHz) Ku Band is 12 and 14 gHz .14.0 and 14.5 gHz are used to uplink; 11.7 and 12.2 gHz are used to downlink. A receiver with dual band capability can receive C and Ku band signals.
Base BandThe unmodulated signal that is delivered from a satellite receiver
Base Band Distribution SystemsUsually used when the viewing areas are close together, and when TV monitors are used for viewing. The base band audio/video output from the satellite receivers is fed directly into the monitor. This form of wiring uses several twisted pair wires which can be very expensive when wiring more than 50 feet because of the need for many amplifiers and splitters. The picture quality is much sharper using a base band system, than with any other system
Basic Rate Interface - BRIThe basic subscriber loop for one or two users, which delivers two 64 kpbs B channels and one 16 kbps D channel over a standard twisted pair loop. Each circuit-switched B channel can transmit voice or data simultaneously. The D channel transmits call control messages and user packet data
Batched Communication The sending of a large body of data from one station to another station network, without intervening responses from the receiving unit.
Baud A unit of digital transmission signaling speed derived from the duration of the shortest code element. Speed in bauds is the number of code elements per second.
300 Baud is low, 2400 Baud and 9600 Baud are much faster and common for
transmitting data by computer
BBS - Bulletin Board System/ServiceThe BBS is an area within a network where
users can "post" information for public display, in much the same way one posts
information on a regular bulletin board. Most networks dedicate a bulletin board to
special interest areas, such as education or computer care
Beyond the Horizon RegionThat physical region beyond the optical horizon with which line-of- sight radio communications is not normally possible, but can occur if atmospheric conditions are such to cause beam bending or forward scattering of the radio signal.
Bicycle TapesThe process whereby video tape material is distributed by sending or "bicycling" the tape after presentation to the next site for its scheduled presentation
Bidirectional FlowA pathway allocating two-way data or communication exchange; flow in either direction represented on the same flow line in a flowchart
BinaryNumbering system with two possible states, on or off as designated by 0 and 1
BISDN - Broadband ISDNIs expected to offer dedicated circuits, switched circuits and packet services at rates of 155 Mbps and above.BISDN is currently in the conceptual stage, and the term refers to a family of services being defined by the standards organizations. The goal of BISDN is to take advantage of the immense amount of raw bandwidth being made available due to the proliferation of fiber cable plant, and to enable customers to send data, voice, and video at high speeds and in an integrated manner. BISDN is expected to be fully defined in 1993-95, and deployment will take place in the latter half of the decade. SONET-based fiber will serve as the delivery vehicle for BISDN services. BISDN will employ the concept of cell relay (Asynchronous Transfer Mode - ATM), which uses a transmission scheme based on small, fixed-sized (53-byte) cells. These cells carry address and raw information, and the carrier networks will use address information to route the cells to the appropriate destination. As discussed above, frame relay is an interface; in contrast, cell relay is broader in scope and defines the size of the packets and the process for carrying packets across a network. BISDN is expected to encompass different types of services, including datagram service, switched circuits and permanent circuits, and to run at speeds ranging from 155 to 622 mbps. Some services, like SMDS and frame relay, will be in operation before BISDN is introduced, and the BISDN specs are expected to
incorporate these preexisting services.
Binary FilesThose containing information that is not represented in the file by ASCII characters. These may be graphics, formatted files, or even executable programs. In order to send these files, special up- and downloading protocols must be used. Base Two, a number system comprised of zeros and ones, which represent off and on, absence or presence of a pulse. Used to store data
BitA contraction of the words "binary digit," the smallest unit of information. A code element of digital transmission. One bit per second equals one baud "binary digit" single unit of information 0 or 1. See kbps or mbps
Bit DensityA measure of the number of bits received per unit of length or area
Bit Error RateFraction of a sequence of message bits that are in error. A bit error rate of 10-6 means that there is an average of one error per million bits
Bit RateSpeed at which bit positions are transmitted, normally expressed in bits per second (see Baud.)
Bit StreamA continuous string of bit positions occurring serially in time
BITNETAnother, academically oriented, international computer network, which uses a different set of computer instructions to move data. It is easily accessible to Internet users through e-mail, and provides a large number of conferences and databases. Its name comes from "Because It's Time." BITNET is linked to Net North, the Canadian equivalent, and EARN, the European Academic and Research Network, as well as Internet/NREN
Blanking (picture)The portion of the composite video signal whose instantaneous
amplitude makes the vertical and horizontal retrace invisible
Blanking LevelThe level of the front and back porches of the composite video signal
Blanking Pulse1. A signal used to cut off the electron beam and thus remove the spot
of light on the face of a television picture tube or image tube. 2. A signal used to
suppress the picture signal at a given time for a required period
Blanking SignalA specified series of blanking pulses
Block A group of bits, or characters, transmitted as a unit. An encoding procedure is
generally applied to the group of bits or characters for error control purposes
Block Downconverter - BDC Located at the antenna. The multi-conversion process of converting the entire band to an intermediate frequency (4 GHz to 1 GHz) for transmission to multiple receivers, where the next conversion takes place. The BDC receives the signals from the Low Noise Amplifier (LNA) and converts them from the extremely high 4 GHz range to a much lower range, usually around 1 GHz. This range is less critical to signal loss, and permits the use of inexpensive long-run cable to
interconnect with the receiver. Perhaps the biggest advantage of the BDC is the manner
in which it handles the "block" of signals. It can be thought of as a passive device,
converting and passing on to the receiver all of the channels on the satellite (of the
selected polarity). This allows for the installation of multiple receivers through signal splitters, and simultaneous program viewing or taping. Older installations used
downconverters that operated on only one channel, tuned by the receiver. These
downconverters converted the LNA signals to 70 MHz, which provided considerable
flexibility in quality and length of the connecting cables. The BDC method is used by KuBand systems and is also compatible with C-Band receivers
Block-Error RateThe ratio of the number of blocks incorrectly received to the total
number of blocks sent
BounceWhat your e-mail does when it cannot get to its recipient - it bounces back to you - unless it goes off into the ether, never to be found again
Branch Cable A cable that diverges from a main cable to reach some secondary point
Branching A computer operation, such as switching, where a choice is made between two or more possible courses of action depending upon some related fact or condition
BridgeDevice which interconnects three or more telecommunication channels, such as telephone lines. A telephone conference audio bridge links three or more telephones
(usually operated assisted). Usually a meet-me audio bridge or provides a teleconference direct dial access number. Both connect remote sites and equalize noise distortion.
Bridges, Gateway, RoutersDevices that convert LANs to other LANs, computers and WANs by allowing systems running on different media (copper wire, fiber optics, etc.) and protocols (rules to communicate)
Bridging AmplifierAn amplifier connected directly into the main trunk of the CATV system. It serves as a sophisticated tap, providing isolation from the main trunk, and has multiple high level outputs that provide signal to the feeder portion of the distribution network. Synonymous with bridger and distribution amplifier
BroadbandCommunications channels that are capable of carrying a wide range of frequencies. Broadcast television, cable television, microwave and satellite are examples of broadband technologies. These technologies are capable of carrying a
great deal of information in a short amount of time, but are more expensive to use than technologies like telephone which require less band width. Broadband (Wideband) distribution systems. A telecommunications medium that carries high frequency signals;
includes television frequencies of 3 to 6 megahertz. Broadband distribution systems work like cable TV, in that up to twenty channels are available from a single coaxial cable. A main trunk cable will originate at the control room, and run down the hallways of the viewing area. Smaller cables can tie into the main cable at any point along its length. Any room that is near the main cable run can have access to all of the channels on the system. Normal television sets are used, and a variety of channels can be
received by simply changing channels on the television set
Broadband NetworkA local area network (LAN) residing on coaxial cable capable of
transporting multiple data, voice and video channels
BroadcastingThe dissemination of any form of radio electric communications by means of Hertzian waves intended to be received by the public. Transmission through space, utilizing preassigned radio frequencies, which are capable of being received aurally or visually by an audience. The one-way transmission of information
BrokersOrganizations which maintain primary leases or ownership of communications satellite time and provide subleases to teleconference originators
BufferTemporary storage facility used as an interface between system elements whose data rates are different; Memory area in computer or peripheral device used for temporary storage of information that has just been received. The information is held in the buffer until the computer or device is ready to process it. Hence, a computer or device with memory designated as a buffer area can process one set of data while more sets are arriving
Bug A system or programming problem. Also refers to the cause of any hardware or software malfunction. May be random or non-random
Bundle A package that includes several products for one price. For example, a CDROM drive, with controller card, cable, software, and one or more CD-ROMs
Bus Interface An electronic pathway between CPUs and input/output devices. A bus interface for a CD-ROM drive consists of a controller card and cable
Business Television - BTVCorporate use of video transmission for meetings/training
via satellite
Burst 1. In data communication, a sequence of signals counted as one unit in accordance with some specific criterion or measure. 2. A color burst
Burst Modem In satellite communications, an electronic device used at each station that sends high-speed bursts of data which are interleaved with one another. These bursts must be precisely timed to avoid data collisions with multiple stations
Burst TransmissionData transmission at a specific data signaling rate during
controlled intermittent fiintervals
BusA circuit or group of circuits which provide an electronic pathway between two or more central processing units (CPUs) or input/output devices.
Bus ControllerThe unit in charge of generating bus commands and control signals
ByteA group of bits treated as a unit used to represent a character in some coding systems. The values of the bits can be varied to form as many as 256 permutations. Hence, one byte of memory can represent an integer from 0 to 255 or from -127 to +128. The unit of computer memory typically consists of eight bits; 64K, 64,000 bytes or 64 kilobytes
BytePrimary and secondary memory (RAM and magnetic media) are measured in kilobytes (1,024, or 210 bytes) and megabytes (one million bytes)


CALLING PARTY PAYSA billing method in which a wireless phone caller pays only for making calls and not for receiving them. The standard American billing system requires wireless phone customers to pay for all calls made and received on a wireless phone.
CELLULAR TECHNOLOGYThis term, often used for all wireless phones regardless of the technology they use, derives from cellular base stations that receive and transmit calls. Both cellular and PCS phones use cellular technology.
CLOSED CAPTIONINGA service for persons with hearing disabilities that translates television program dialog into written words on the television screen.
COMMERCIAL LEASED ACCESSManner through which independent video producers can access cable capacity for a fee.
COMMON CARRIERIn the telecommunications arena, the term used to describe a telephone company.
COMMUNICATIONS ASSISTANTA person who facilitates telephone conversation between text telephone users, users of sign language or individuals with speech disabilities through a Telecommunications Relay Service (TRS). This service allows a person with hearing or speech disabilities to communicate with anyone else via telephone at no additional cost.
COMMUNITY ANTENNA TELEVISION (CATV)A service through which subscribers pay to have local television stations and additional programs brought into their homes from an antenna via a coaxial cable.
CRAMMINGA practice in which customers are billed for enhanced features such as voice mail, caller-ID and call-waiting that they have not ordered.
C-BandA category of satellite transmissions which transmit from earth at 4.0 to 6.0 GHz and receive from the satellite at between 3.7 and 4.2 GHz which are also shared with terrestrial line-of-sight microwave users. This band of transmissions has less path loss than the other standard used for satellites (Ku-Band) but must have a large antenna for the same receiver input power level due to its use of longer wavelength frequencies. Other problems relating to the use of C-Band include the shared use of these frequencies with terrestrial microwave transmission which cause interference with the weaker satellite signals in certain areas
Cable/Cable Television A broadband communications technology in which multiple
television channels as well as audio and data signals are transmitted either one way or bidirectionally through a distribution system to single or multiple specified locations. Uses coaxial cable to transmit programs. Direct-by-wire transmission to homes from a common antenna to which these homes are linked. Cable companies provide the service in most cases. Distinguished from television reception through a roof-top antenna that picks up the broadcast signal. The only acronym was CATV, denoting community antenna television
Cable Communications Policy Act of 1984This act, passed by Congress in 1984, updated the original Communications Act of 1934. The primary changes dealt with cable television regulation, theft of service, equal employment opportunity (EEO) an various licensing procedure changes.
Cable CompatibleGenerally refers to consumer devices, such as television sets and videocassette recorders, that are designed and constructed to allow direct connection of a CATV subscriber drop to the device. Frequently, they have a tuner capable of receiving cable channels other than 2-13 (e.g., midband, superband, and hyperband channels). Even though a device may be cable compatible, it may still require an external descrambler to receive scrambled channels such as the premium pay channels or pay-per-view channels
CacheIn a processing unit, a high-speed buffer storage that is continually updated to contain recently accessed contents of main storage. Its purpose is to reduce access time. A holding area for data within the CD-ROM drive itself or on its interface board, that allows the system a method for matching data transfer rates and presentation speed requirements
CADComputer Aided Design
CAIComputer Assisted Instruction
CameraIn television, an electronic device utilizing an optical system and a lightsensitive pick-up tube to convert visual images into electrical impulses. Camera Control Unit # CCU: An electronic device that provides all the operating voltages and signals for the proper set up, adjustment and operation of a television camera.
Candle PowerA measure of intensity of a light source in a specific direction
Carrier-to-Noise RatioIn cable television, the ratio of peak carrier power to root mean square (RMS) noise power in a 4 MHz bandwidth
CATV- Community Antenna TelevisionA broadband communications system capable of delivering multiple channels of entertainment programming and nonentertainment information from a set of centralized antennas, generally by coaxial cable, to a community. Many cable television designs integrate microwave and satellite links into their overall design, and some now include fiber optics
Carrier Vendor of transmission services operating under terms defined by the FCC as a common carrier. Owns a transmission medium and rents, leases or sells portions for a set tariff to the public via shared circuits
CAV - Constant Angular VelocityA disk that rotates at a constant rate of speed. Examples are hard drives, floppy disks, magneto-optical discs and some videodiscs. A CAV videodisc permits access to video within seconds, allows for up to 54,000 still frames, or may contain up to 30 minutes of full motion video (or any combination of stills and video). (See CLV)
CBT - Computer Based TrainingThe use of interactive computer or video programs
for instructional purposes
CCITTConsultative Committee on International Telephony and Telegraphy; An international standards group
CCITT StandardTransmission rate of Px64 or multiples
CCL - Connection Control LanguageA scripting language that allows the user to
control a modem
CCTVClosed-Circuit Television. The system for sending cable signals to subscribers or designated locations
CD-Audio Also called CD-DA for Compact Disc-Digital Audio. The use of CDs to record music in digital audio format. The disc holds a sequence of audio tracks. Each can be a very high-fidelity stereo recording. These discs can be played on conventional
CD players, CD-I systems and at least some CD-ROM drives. Standards for this are called the Red Book
CD audio jackAn outlet on a CD-ROM drive that provides audio playback through speakers or headphones. Only Red Book, or true CD-Audio sound can be heard from the audio jack on a CD-ROM drive
CD-ROM Compact Disc - Read Only MemoryCD-ROM discs can store a variety of
data types including text, color graphics, sound, animation and digitized video that can
be accessed and read through a computer. A disc can store up to 600 megabytes of
data, much more information that can be stored on a 3.5 inch compute disk, which hold
up to 1.4 megabytes. This makes CD-ROM an inexpensive medium for storing large amounts of data. Because CD-ROM was not designed to store digitized, full-motion video, compression technology is important in compressing data to fit on a disc as well as decompressing data for playback
CD-I1. Compact Disc-Interactive. Stores text, audio, video, images and animation. Requires a CD-I player and will not work on a regular CD-ROM player. 2. This interactive multimedia system, developed by Philips and Sony, connects to a television and stereo audio system. The standards for this are called the Green Book.
CD-RCD-Recordable Term used to describe special players and media which enable the creation of a single CD-ROM, written from the PC as if it were a magnetic disk drive. The end product, however, is a read-only disc: it cannot be erased or written over. Therefore, this technology is also known as "write-once CD." See CD-WO
CD-ROMA laser-encoded optical memory storage medium, defined by the Yellow Book standard
CD-ROM Drive A computer peripheral that plays CD-ROMs
CD-ROM XACD-ROM Extended Architecture: A compact disc standard that permits the interleaving of compressed audio and video tracks for sound and animation synchronization. Based on the Yellow Book, it also uses some elements of the Green Book (CD-I)
CD-WO - Compact Disc-Write OnceA term that describes compact discs that can be
written to directly (rather than mass produced) with a laser recorder. Recent developments allow the CD-WO to be appendable. CD-WO media is physically defined by the Orange Book standard, Part II, and a proposal for the logical format has been submitted to ECMA by the Frankfort Group
Center ClipperVariable attenuator which is used to eliminate any residual echo left by the echo canceller. A key difference between one canceller and another is the manner in which this center clipper operates. In a high quality canceller, the center clipper will operate very rapidly and smoothly, resulting in no residual echo during double-talk and no clipping of syllables. The center clipper is in essence a level- activated switch.
Signals above the threshold level are passed unaltered and signals below the threshold are blocked. When speech is present in both directions, the center clipper tends to
mutilate the speech signal, adding audible amounts of harmonic and intermodulation distortion. This distortion is often referred to as "glitch" and sounds remarkably like its
name when it occurs. The transmit signal can be totally chopped out if the level of the transmit signal drops below the estimated level of returning echo
Central OfficeThe physical location where communications carriers terminate customer lines and locate the switching equipment that interconnects those lines
Central Processing Unit - CPUThe unit of a computer that includes circuits controlling the interpretation and execution of instructions
ChannelA signal path of specified bandwidth for conveying information. 1. A halfcircuit; 2. A radio frequency assignment (which is dependent upon the frequency band and the geographic location). Channel capacity in a cable television system is the number of channels that can be simultaneously carried on the system. Generally defined in terms of the number of 6 MHz (television bandwidth) channels.
CFDA - Catalog of Federal Domestic AssistanceThe CFDA is a government-wide compilation of federal programs, projects, services and activities that provide assistance or benefits to the American public. The primary purpose of the CFDA is to assist users in identifying programs that meet specific objectives of a potential applicant, and to obtain general information on federal assistance programs. The catalog is published once yearly, usually in June. An update occurs around December
CFR - Code of Federal RegulationsThe CFR is the "book" of federal laws and regulations. Usually referenced like this, 34 CFR 74.137. The "34" indicates that the subject of the regulation is education
Character GeneratorAn alphanumeric text generator, a typewriter like device,
commonly used to display messages on a television set. Chyron is a brand name for a character generator which is often mistakenly used to cover all character generators
generically. Some sophisticated models also include color, graphics, and mass memory for text storage
Charge-Coupled Device - CCDA solid-state device used in many television cameras
to convert optical images into electronic signals. These imagers are organized into rows and columns called pixels. The charge pattern formed in the CCD pixels when light strikes them forms the electronic representation of the image
ChipA thin silicon wafer on which electronic components are deposited in the form of integrated circuits; the basis of digital systems
Chip SetsApplication-specific integrated circuits (ASICs) are being developed for use in video application products such as codecs, desktop video, and home satellite entertainment. ASICs operate more like computer hardware. Programmable chips operate much like computer software. The chip sets meet the CCITT H.261 compression standard and will be the driving force in the widespread use of video communications technology because they will lower the cost and open up the
technology to a much larger group of users
Chroma Key In color television, an electronic matting process of inserting one image over a background. Used very commonly with weathercasters who are standing in front of a blank wall painted process blue. The electronics remove the blue and insert the weather map so that on the television screen the two images merge and the weathercaster appears to be standing in front of a large map painted on the wall.
Chrominance SignalThe color signal component in color television that represents
the hue and saturation levels of the colors in the picture
Circuit Means of two-way communication between two or more points. 1. In communication systems, an electronic, electrical, or electromagnetic path between two or more points capable of providing a number of channels. 2. Electric or electronic part. 3. Optical or electrical component that serves a specific function or functions. Circular Polarization: A mode of transmission in which signals are downlinked in a rotating corkscrew pattern. A satellite's transmission-capacity can be doubled by using both right-hand and left-hand circular polarization
Closed Circuit Television - CCTVA private television system in which signals are sent usually via cable, to selected viewing points throughout the distribution system but are not broadcast to the public. The signal does not have to meet FCC commercial specifications
CLV - Constant Linear VelocityA disc that rotates at a varying rate of speed. Examples are CD-Audio, CD-ROM, CD-I, CD-ROM XA, and some videodiscs. CLV
videodiscs may contain up to one hour of full motion video, but still frames and quick access time are forfeited. (See CAV.)
CMCComputer mediated communication
C/N - C/NR - Carrier to Noise RatioRefers to the ratio of the satellite carrier (or signal) to noise level in a given channel. Usually measured in dB at the LNA output. Coaxial Cable - Coax: A type of metal cable used for broadband data and cable systems. It has excellent broadband frequency characteristics, noise immunity and physical durability. Consisting of a center conductor in the form of a tube which carries broadband signals by guiding high frequency electromagnetic radiation, insulating dielectric, conductive shield, and optional protective covering.
Co-Channel InterferenceInterference on a channel caused by another signal
operating on the same fichannel.
CodecA COder-DECoder converts analog signals, (voice or video), into digital form (1 or 0) for transmission over a digital medium and, upon reception at a second codec, reconverts the signals to the original analog form. Two codecs are needed - one at each end of the channel
Collaborative Learning Collaborative learning involves a group working together
through technology to delve into content. Students can electronically access other students, the instructor and resources
Color Bars and ToneA color standard test pattern used by the television industry toadjust equipment to standard levels. The tone is generated at a certain preset frequency so that audio levels can be set
Color Burst In NTSC terminology, refers to a burst of approximately nine cycles of 3.58 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 SignalAny signal at any point in a color television system for wholly or partially controlling the chromaticity values of a color television picture
Color Subcarrier In NTSC color, the 3.58 MHz subcarrier whose modulation
sidebands are interleaved with the video luminance signal to convey color information
Color TransmissionA method of transmitting color television signals which can
reproduce the different values of hue, saturation, and luminance which together make up a color picture
Combining NetworkA passive network which permits the combining of several
signals into one output with a high degree of isolation between individual inputs; commonly used in CATV headends to combine the outputs of all processors and modulators into a single coaxial cable input. Synonymous with combiner
Command LineOn Unix host systems, this is where you tell the machine what you want it to do, by entering commands
Common CarrierUsually a telecommunications company that owns a transmission medium and rents, leases or sells portions for a set tariff to the general public via shared circuits through published and nondiscriminatory rates. In the U.S., common
carriers are regulated by the FCC or various state public utility commissions. Communications Satellite Corporation - COMSAT: A common carrier service that provides commercial communications services
Communications Satellite Relay system in orbit above earth for telecommunications
signals (voice, video, data); require earth stations to transmit and receive signals at the ground locations. Commonly called a "bird."
Communications SoftwareA program that tells a modem how to work
CompatibleDescribes different hardware devices that can use the same software or programs without modification, or with appropriate software
CompressionThe application of any of several techniques that reduce the amount of information required to represent that information in data transmission. This method reduces the required bandwidth and/or memory
Compressed VideoProcesses video images; transmits changes fro one frame to the next which reduces the bandwidth to send them over a telecommunications channel; reduces cost. Also called bandwidth compression, data compression or bit rate
reduction. The most publicized compression techniques are proposed by two expert groups, that of JPEG (Joint Photographic Expert Group) and MPEG (Moving Picture Expert Group), who are defining methods for image compression in still frame and realtime video. The algorithm used by these two groups is called discrete cosine transform(DCT). DCT transforms a block of pixels into a matrix of coefficients and estimates redundancy in the matrix. The advantage of JPEG and MPEG is that the algorithms are
symmetrical; that is, the same amount of processing is required for the encode and decode functions. These are ideal for two-way applications such as videoconferencing
CompuServe - CompuServe Information Service - CISOne of the oldest and largest commercial computer network services
ComputerA functional unit that can perform substantial computations, including numerous arithmetic operations or logic operations, often without intervention by a human operator
Computer-Aided Design - CADA computer system whereby engineers create a design and see the proposed product in front of them on a graphics screen or in the form of a computer printout
Computer ConferencingAllows individuals at different locations to communicate with each other through computers. This could be through a chat room, e-mail, a classroom environment created by software. It might include text, audio, video, or shared work spaces on which all participants can type or draw
ConferencingA term used to indicate when several network users communicate on a particular subject. Conferences can be "live" or conducted via a BBS
Connect TimeTime period during which a user is utilizing a computer on-line - or directly connected with the computer
Connect Time ChargesMost networks charge users for the time they spend on-line.
These are referred to as connect time charges. The amount charged depends on the network's fee schedule. Users must also pay a separate fee if the call to connect is toll
Control RoomA room separate from a studio in which the director, the technical director (TD), the audio engineer, and other technical and program assistants control program production
CONUSContiguous United States
ConsortiumVoluntary group affiliated for a purpose. Consortia is plural
Continuous Presence VideoSimultaneous and continuous pictures of participants
Convergence - Digital FusionThe merging of video, audio, and data communications
through digitization of the media. The equipment to receive the signals is projected to be a telecomputer
Cooperative LearningThis learning model is based on specific group rewards for
team members' learning and task specialization. Students work together to solve problems and locate information
CoursewareSoftware used in teaching. Often used to describe computer programs designed for the classroom
CrashAn abrupt, unplanned computer system shutdown caused by a hardware or software malfunction
CrawlA visual technique; electronically generated words or graphics that move horizontally or crawl across the screen, usually at the bottom
Crawl Space Space for textual messages usually at the bottom of the television screen
Credits The names of people on whom the production can be blamed. Electronically generated words that usually move horizontally up the screen like a scroll, or inserted a page at a time
CRENCorporation for Research and Educational Networking
Crosstalk1. Undesired transfer of signals from one circuit to another circuit. 2. The phenomenon whereby a signal transmitted on one circuit or channel of a communications system is detectable or creates an undesirable effect in another circuit or channel
CueSignal to start, pace, or stop any type of production activity or talent action
CursorA symbol on the display of an editing or display terminal that can be moved up, down, or sideways and indicates where the next character is to be located or where "home" or beginning is located
CutA command that stops all action in actual production; or a visual technique for changing abruptly from one picture to an entirely different one; for example, quick cuts in which many different visuals appear rapidly one after another on the screen
CyberphobicA person who is fearful of working in cyperspace
CyberspaceCoined by science fiction writer William Gibson in the 1970s, it describes
the virtual place of computer memory, networks, and multimedia


DIAL AROUNDLong distance services that require consumers to dial a long-distance provider’s access code (or "10-10" number) before dialing a long-distance number to bypass or "dial around" the consumer’s chosen long-distance carrier in order to get a better rate.
DIGITAL TELEVISION (DTV)A new technology for transmitting and receiving broadcast television signals. DTV provides clearer resolution and improved sound quality.
DIRECT BROADCAST SATELLITE (DBS/DISH)A high-powered satellite that transmits or retransmits signals which are intended for direct reception by the public. The signal is transmitted to a small earth station or dish (usually the size of an 18-inch pizza pan) mounted on homes or other buildings.
D1 and D2Digital tape component and composite formats (respectively) used for professional video recording. D1 is costlier than D2. Both can go through many generations of dubbing without visible loss of picture quality
DaemonAn otherwise harmless Unix program that normally works out of sight of the user. On the Internet, you'll most likely encounter it only when your e-mail is notdelivered to your recipient - you'll get back your original message plus an ugly message from a "mailer daemon" saying the message was undeliverable
Daisy ChainA way to connect computers - one after another along a single line
DARPADefense Advanced Research Projects Agency of the Pentagon. Replaced ARPA
DataAny and all information, facts, numbers, letters, symbols, etc. which can be acted on or produced by the computer
DatabaseOrganized collection of files and information stored on a computer disk/drive available for update and retrieval
Data Communications1. The movement of encoded information by means of electrical or electronic transmission systems. 2. The transmission of data from one point to another over communications channels
Data CompressionA technique that saves storage space by eliminating gaps, empty
fields, redundancies, or unnecessary data to shorten the length of records or blocks
DBS - Direct Broadcast SatelliteService uses high powered satellites to broadcast
multiple channels of TV programming to inexpensive, small-dish antennas at homes for direct on-site reception of signals
DCT - Discrete Cosine TransformCompression algorithm
DebugTo detect, trace, and eliminate mistakes in computer programs or in other software
Dedicated LinesLeased telecommunications circuits that are devoted to a specific
application; a circuit designated for exclusive use by two users; i.e., for interactive portion of a teleconference
Dedicated System Videoconferencing equipment, transmission circuits, and
teleconferencing facilities that are permanent and used on a regularly scheduled basis as opposed to rented for a one-time or ad hoc event
DefaultA standard setting or action taken by hardware or software if the user has not specified otherwise
DefinitionAlso called resolution. The fidelity with which detail is reproduced by a television system ranging from a fuzzy to a sharp appearance
Degausser1. Demagnetizer. 2. A device for bulk erasing magnetic tape
DelayTime it takes for a signal to go from sending station through the satellite to receiving station
Demodulate To retrieve an information carrying signal from a modulated carrier. A demodulator is a device that removes the modulation from a carrier signal
Dial up - DialupTo call another computer via modem. A connection or line reached by modem, as in "a dialup line
Dial-Up TeleconferencingUsing public phone line to connect with a teleconference, either with or without operator assistance
Dielectric A non-conductive insulator material between the center conductor and shield of coaxial cable. The dielectric constant determines the propagation velocity
Digirati Literati who do everything digitally
DigitalDiscrete bits of information in numerical steps. A form of information that is represented by signals encoded as a series of discrete numbers, intervals or steps, as contrasted to continuous or analog circuits. Digital signals can be sent through wire or
over the air. The method allows simultaneous transmission of voice and data. All digital technology is emerging as the primary transmission mode for voice, video, data and
facsimile; Information represented by signals encoded as a series of discrete numbers, intervals or steps. Can be sent through wire or over the air. Allows simultaneous transmission of voice, video and data
Digital ComputerA computer that operates on discrete data by performing arithmetic and logic processes on these data
Digital MediaRefers to any type of information in digital form including computer generated text, graphics and animations, as well as photographs, animation, sound, and video
Digital TransmissionThe transmission of information in the form of "1s" and "0s." Information customarily sent in this form is related to computer data traffic which isalready in digital form. Other communications include audio and video
Digital Video Effects - DVEVideo effects accomplished through digital devices that manipulate the video; e.g., page turns, revolves, boxes that zoom into and out of the picture, images that turn into pixels, etc
Digitized AudioAllows the incorporation of audio materials with other media to
present information over a computer network or through the Internet. With this method,the audio is contained.Various software programs "stream" the audio signal so that it
can be heard as it is being said
DigitizerA device that converts an analog signal (either images or sound) into a digital signal that can be manipulated on the computer. Video capture boards convert video images from video sources such as the VCR or video camera, while sound digitizers take any sounds, the spoken word as well as music off of a cassette or CD player, and turn them into digital data. That data can be edited using sound editing and multimedia software
DiodeAn electronic device used to permit current flow in one direction and to inhibit current flow in the other
Directional MicrophoneA microphone that detects and transmits sound from only a
certain direction. Useful in preventing unwanted sound from being transmitted
Direct Read After Write - DRAWA laser based technology for recording data on a video disk
DiscPreferred usage (spelling) of the term for reference to optical storage media, such as CD-Audio, CD-I, CD-ROM, videodisc, or WORM
DiskPreferred usage (spelling) of the term for reference to magnetic media, such as floppy and hard disks
Disk - DiscA record-like magnetic-coated piece of material that can store digital information; may be a hard disk or pliable floppy disk
Disk DriveA computer data storage device in which data is stored on the magnetic coating (similar to that on magnetic tape) of a rotating disk
DishParabolic antenna. Primary element of a satellite earth station; sends and/or receives satellite signals. Usually bowl-shaped; concentrates signals to a single focal point. The antenna cross section exposed to the signal is the aperture
DisplayThe visual presentation on the indicating device of an instrument
DissolveGradual transition from one television picture to the next by fading out one picture and simultaneously fading in another
Distance LearningEducational situations which use telecommunications devices to deliver content, exchange information, allow student interaction, and other educational activities. Technologies might include one, all, or some of the following technologies; satellite, DBS, compressed video, broadcast television, cable, fiber optics, computer, classroom created in a computer environment, telephone, computer chat rooms, audio conferencing, e-mail, listservs, audio tapes, video tapes, CD-ROMs, simulations, textbooks, worksheets/workbooks, Internet access to resources, fax machine, instructor/facilitators at one or all sites. Learners could be in age groups for early childhood, K-12, higher education, or training. Courses might be for credit, continuing education credit, or required by an employer. There has been an effort to limit the number of technologies included in this definition. This counter-productive effort minimizes the overall impact of distance learning and grants "status" to a few. Because the use of multiple technologies meets the learning style needs of all students, the inclusion of many technologies represents the student-centered approach that we endorse
DistortionAn undesired change in wave form of a signal in the course of its passage through a transmission system
Distributed Data ProcessingData processing in which some or all of the processing, storage, and control functions, in addition to input-output functions, are situated in different places and connected by transmission facilities
Distributed FunctionThe use of programmable terminals, controllers, and other devices to perform operations that were previously done by the processing unit, such as managing data links, controlling devices, and formatting data
Distribution A way to limit where your Usenet postings go. Handy for such things as "for sale" messages or discussions of regional politics
Distribution SystemsAny program that can be received by the satellite antenna, can be distributed into several viewing areas. The distribution system is one or more wires that run from the earth station control room, into several classrooms or conference rooms. Broadband wiring systems use a single coaxial cable, while baseband systems use several twisted-pair wires. Both systems must be custom designed for each location, using high output amplifiers and exact cable lengths
DomainThe last part of an Internet address, such as "" The zones include:
mil-military site
com-commercial organizations
gov-government body or department
net-networking organization
int-international organization (mostly NATO)
org-anything that doesn't fit elsewhere, such as a professional society
Domestic SatelliteA satellite that provides communication services primarily to one
DOSDisk Operating System
DotTo impress the Net veterans encountered, parties say "dot" instead of "period." For example: "My address is john at site dot domain dot com."
Dot fileA file on a Unix public-access system that alters the way the user or the messages interact with that system. For example, a user's .login file contains various parameters for such things as the text editor used when a message is sent. When an ls command is done, these files do not appear in the directory listing; do ls -a to list them
Double speed driveRefers to a CD-ROM drive that will read certain kinds of data faster than the standard requires (155KB/sec). Many drives now have 300KB/sectransfer rates (also known as twice the standard, or 2X); at least one claims 600KB/sec (4X)
Double-TalkThe situation where parties at both ends of a conference are speaking simultaneously. A quality echo canceller will provide a continuous speech path in both directions during double-talk
DownWhen a public-access site runs into technical trouble, and you can no longer gain access to it, it's down
DownconverterA device used to lower the frequency of any signal
DownlinkTransmission of radio frequency signals from a satellite to an earth station (verb). A satellite receiving station (noun)
Download 1. Transfer data from a main computer or memory to a remote computer or terminal. 2. There are several different methods, or protocols, for downloading files, most of which periodically check the file as it is being copied to ensure no information is inadvertently destroyed or damaged during the process. Some, such as XMODEM, only let you download one file at a time. Others, such as batch-YMODEM and ZMODEM, let you type in the names of several files at once, which are then automatically downloaded
DownstreamAn audio or video signal traveling from the cable TV headend to a
subscriber point in the community
Drive bayThe opening in a computer chassis designed to hold a floppy drive, hard drive, CD-ROM drive, tape drive or other device. May be half-height or full-height, exposed or internal
Drop-OutsBlack or white lines or spots appearing in a television picture originating from the playback of a video tape recording
DS1Digital signal level 1; a digital transmission format in which 24 voice channels are
multiplexed into one T1 channel
DS3Digital signal level 3; a telephony term describing the 45 mbps signal carried on a T3 facility. It is most often associated with broadcast video transmission. Although the broadcast purest will rightfully point out that as a digital signal it is not a true broadcast quality RS-250B standard signal, it is the nearest approximation to a broadcast signal in a digital environment
DSPDigital signal processing
DTMF - Dual Tone Multiple FrequenciesStandard telephone signaling technique
which can be used through any transmission medium of voice grade or better. He technique is often used for remote switching control functions
Dual Band CapabilityMany receivers are capable of both C and Kuband operation
Dub - Dupe - DuplicateThe duplication of an electronic recording. Dubs can be made from tape to tape in video, or from record to tape in audio. In video, one generation of quality is usually lost between each duplicate except when using high grade broadcast equipment and one inch wide tape. Usually a video tape that appears fuzzy and the colors have lost clarity, it is a 3rd, 4th, or 5th generation tape - in other words, a copy, of a copy, of a copy, of a copy, of a copy
DuplexIn a communications channel the ability to transmit in both directions
DVI - Digital Video InteractiveDVI is a programmable (variable bit and frame rate) compression and decompression technology developed by Intel offering two distinct
levels and qualities of compression and decompression for motion video. Both PLV and RTV use variable compression rates. Production Level Video (PLV), a proprietary asymmetrical compression technique that is well suited for encoding full motion, color video requires compression to be performed by Intel at its facilities or licensed encoding facilities set up by Intel. PLV emulates MPEG. It has a very high image quality. Real Time Video (RTV) provides comparable image quality to frame-rate (motion) JPEG and uses a symmetrical variable rate compression. To provide expanded still image editing features, future versions of Intel's DVI will be JPEG compliant.


E-MAILAlso called electronic mail, refers to messages sent over the Internet. E-mail can be sent and received via newer types of wireless phones, but you generally need to have a specific e-mail account.
ENHANCED SERVICE PROVIDERSA for-profit business that offers to transmit voice and data messages and simultaneously adds value to the messages it transmits. Examples include telephone answering services, alarm/security companies and transaction processing companies.
EN BANCAn informal meeting held by the Commission to hear presentations on specific topics by diverse parties. The Commissioners, or other officials, question presenters and use their comments in considering FCC rules and policies on the subject matter under consideration.
E-LayerA heavily ionized signal-reflecting region location 50-70 miles above the surface of the earth, within the ionosphere
E-mail - Electronic mailThe term for private messages sent as files from one
computer to another, either over a local area network (LAN), or via modem over the phone lines. E-mail is like having your own private mail box on a network. Used as both a noun and verb. Mail can be sent between Internet and commercial services such as American On Line
Earth StationThe location antenna used to send or receive signals to satellites normally located in the geostationary orbit. A parabolic antenna and associated electronics for receiving or transmitting satellite signals
EchoThe reflections of signal energy that cause it to return to the transmitter or to the receiver
Echo CancellerEliminates audio transmission echo. A telephone line echo canceller produces a synthetic replica of the echo it expects to see returning and subtracts it from the transmitted speech. The replica it creates is based on the transmission
characteristics of the telephone cable between the echo canceller and the telephone set
Echo ReductionA newer method of echo control, developed in 1988, uses attenuation in a new way to subjectively reduce the returned echo without the mutilation (choppiness, level drops, distortion) found in suppressers or center clippers. It rapidly and momentarily applies a variable amount of attenuation in between transmitted speech peaks (where the echo would be audible). It compares the transmit and receive signals to determine the likelihood of objectionable echo in the transmit signal, then calculates and inserts the appropriate amount of attenuation for that instant to control the echo. During outgoing speech peaks, the echo is masked by the strong local speech and rendered inaudible to the listener so that no attenuation is required
EditorA computer program used to edit (prepare for processing) text or data
Educational Access ChannelA cable television channel specifically designated for
use by local education authorities
EdutainmentMultimedia designed for teaching. It's based on the theory that learning doesn't have to be boring
EFMEight to fourteen modulation
Electrically Alterable Read Only Memory - EAROMA type of memory that is nonvolatile, like ROM, but can be altered, or have data written into it, like RAM
Electromagnetic InterferenceAny electromagnetic energy, natural or man-made, which may adversely affect performance of the system
Electromagnetic Spectrum The frequency range of electromagnetic radiation that
includes radio waves, light and X-rays. At the low frequency end are sub-audible frequencies (e.g., 10 Hz) and at the other end, extremely high frequencies (e.g., X-rays, cosmic rays)
Electronic Blackboard or WhiteboardA device that looks like an ordinary blackboard or whiteboard, but has a special conductive surface for producing free-hand information that can be sent over a telecommunications channel, usually a telephone line
Electronic EditingThe process by which audio and/or video material is added to a previously recorded tape in such a manner that continuous audio and/or video signals result
Electro-Mechanical PenA device that has an electronic pen with a mechanical arm for producing free-hand information that can be sent over a telecommunication channel, usually a telephone line
Electronic Editing In videotapes, a process by which picture and sound elements (live or pre- recorded) are joined together without physically cutting the tape. In sophisticated
editing suites, this is done by computer
Electronic Mail - E-MailA system of electronic communication whereby an individual sends a message to another individual or group of people; includes computer mail and facsimile (FAX)
ElevationThe location of the satellite in the sky from your viewing site. How high above the horizon the satellite is, which is called elevation or altitude which is measured in degrees
EMACSA standard Unix text editor preferred by Unix types that beginners tend to hate
EMIElectronic mediated instruction
EmoticonSee "Smiley"
EncoderA device that electronically alters a signal (encrypts) so that it can be clearly seen only by recipients that have a decoder which reverses the encryption process
EncryptionAn encoder electronically alters a signal so that it can be clearly seen only by recipients who have a decoder to reverse encryption. Selective addressability/scrambling designates receivers to descramble a signal. Each decoder has a unique "address."
End of Tape SensingA form of sensing (optically or mechanically) that automatically stops the tape transport at the end of tape or upon breakage of tape
End UserThe ultimate last user of a telecommunications system whether or not it is a student within a school, business or a subscriber on a cable television system
ENGElectronic news gathering
EnterTo place on the line a message to be transmitted from a terminal to the computer
EPROMErasable-Programmable Read-Only Memory
EPS - Electronic Performance Support SystemA computer supported just-in-time information system that might hold instruction manuals and other information on how to perform the tasks at hand
EROM - Erasable Read-Only MemoryIn a computer, the read-only memory (ROM) that can be erased and reprogrammed. Synonymous with erasable-programmable readonly memory (EPROM)
ESEAElementary and Secondary Education Act of 1965. This acronym is used mainly when referring to programs by their legislative authorization. The most common example is the "Chapter 1" series of programs
EthernetBaseband protocol and technology developed by Xerox and widely supported by manufacturers; a packet technology that operates at 10 mbps over coaxial cable and allows terminals, concentrators, work stations and hosts to communicate with each other
ETVEducational television
EudoraE-mail program
ExecuteTo perform the operations required by an instruction, command or program


FREQUENCY MODULATION (FM)A signaling method that varies the carrier frequency in proportion to the amplitude of the modulating signal.
F2F - Face to FaceWhen you actually meet those people you been corresponding with/flaming
FacilitatorIn adult education (androgogy), the person responsible for a class who acts as a guide and resource to the students. The person responsible for the local component of a video teleconference site is normally called a facilitator
Facsimile - FAXA devce which uses a form of electronic transmission allowing movement of hard-copy documents from widely separated geographic areas via a telecommunications channel, usually a telephone line. Usually called a FAX machine now but previously was called a telecopier
FAQ - Frequently Asked Questions A compilation of answers to these. Many Usenet newsgroups have these files, which are posted once a month or so for beginners
FDDI - Fiber Distributed Data Interface1. Transports data up to speeds of 100 Mbps.
2. FDDI is a high-speed (100Mb) token ring LAN
FDMA - Frequency Division Multiple AccessRefers to the use of multiple carriers within the same satellite transponder where each uplink has an assigned frequency slot and bandwidth
Federal Communications Commission (FCC)An independent government agency established by the Communications Act of 1934 to regulate the broadcasting industry. The Commission later assumed authority over cable. The FCC is administered by seven commissioners and reports to Congress. The FCC assigns broadcasting frequencies, licenses stations, and oversees interstate communications
FEC - Forward Error CorrectionAdds unique codes to the digital signal at the source
so errors can be detected and corrected at the receiver
FeedbackIn video; wild streaks and flashes on the monitor screen caused by re-entry of a video signal into the switcher and subsequent over-amplification. In audio, piercing squeal from the loudspeaker caused by the accidental re-entry of the loudspeaker sound into the microphone and is over-amplified. Feedback can also occur when using a conference telephone while the TV volume is too loud
Feeder CablesThe coaxial cables that take signals from the trunk line to the subscriber area and to which subscriber taps are attached. Synonymous with feeder line
FetchMacintosh program for retrieving files via FTP
Fiber OpticsCommunications medium based on a laser transmission that uses a glass or plastic fiber which carries light to transmit video, audio, or data signals. Each fiber can carry from 90 to 150 megabits of digital information per second or 1,000 voice Telecommunications Glossary/32 channels. Transmission can be simplex (one-way) or duplex (two-way) voice, data, and video service
FieldOne-half of a video frame two fields equal one frame or a full video screen. One field will contain all of the odd or even scanning lines of the picture
Field Blanking IntervalThe period provided at the end of the field picture signals primarily to allow time for the vertical sweep circuits in receivers to return the electron beam completely to the top of the raster before the picture information of the next field begins
FileAn organized collection (in or out of sequence) of records related by a common format, data source or application
File ServerA component of a local area network, or LAN, which stores information for use by clients, or workstations
Filename ExtensionA three-letter (usually) code at the end of a filename that give some indication as to the type of file in non-Macintosh environments that lack icons or other methods of identifying files. Common extensions include .txt for text files, .hqx for BinHexed files, .sea for a self-extracting file, and .sit for Stuffit files
Film at 11One reaction to an overwrought argument: "Imminent death of the Net predicted. Film at 11
Film ChainAlso called film island, or telecine. Consists of one or two film projectors, a slide projector, a multiplexer, and a television camera. Converts film and slides to television signals
FingerAn Internet program that lets you get some bit of information about another user or computer, provided they have first created a .plan file
FIPSFederal Information Processing Standard
Fixed Satellite Service - FSSThe earth stations are not mobile. This service generally
provides telephone and TV distribution
Fixed SystemA permanent satellite receive and transmit system. The fixed system is put in place for regular use and broadcasts are made to the same sites repeatedly. The fixed systems are used for employee training, product introduction, meetings and other needs. Most fixed networks are owned by corporations such as Merrill Lynch, HewlettPackard, Sears, J. C. Penney, and General Motors and are not available to outsiders for videoconference use. However, they can receive teleconferences which are of interest to them
FlameOn-line yelling and/or ranting directed at somebody else. Often results in flame wars, which occasionally turn into holy wars
Floppy Disk - FDOut-of-use term for diskette
FM Microwave RadioUltra-high frequency often used to provide the return link in fully interactive systems (simplex). It can also be used in duplex to provide two-way fullmotion video and audio interactivity
FM Broadcast BandThe band of frequencies extending from 88 to 108 MHz
FM-TVFrequency modulated TV
Follow-upA Usenet posting that is a response to an earlier message
FontA complete set of characters for one style of one typeface (and traditionally, in metal type, in one size), including upper and lowercase letters, numerals, punctuation marks, and special characters. Often used to mean the software that renders a particular typeface. Sometimes used interchangeably with typeface
Foo/foobarA sort of on-line algebraic place holder, for example: "If you want to know when another site is run by a for-profit company, look for an address in the form of [email protected]."
FormatAn established system standard in which data is stored
FootcandleThe unit of illumination equal to 1 lumen per square foot
FootprintEarth area covered by a satellite's signal or beam
Format - VideotapeDesignated by the width of tape and method of recording e.g., 2- inch Quad, 3/4-inch U-Matic, 1/2-inch VHS, 1/2-inch Beta, 1/2-inch BetaCam
Format - ProgrammingType of program (drama, documentary, newscast, interview, etc.)
Fortune CookieAn inane/witty/profound comment that can be found around the Internet
Four-Wire CircuitA circuit that has two pairs of conductors (four wires), one pair for the send channel and one pair for the receive channel; allows two parties to talk and be heard simultaneously
Fractal CompressionCompression technique which uses real-time adaption of the numbers of bits allocated to different colors based upon the present scene
FragmentationStoring parts of a file in disparate available space on a disk, rather than contiguously
Frame Full screen or frame of video is made up of two fields. Thirty frames is one second of video
Frame RelayA high speed interface between switches and T1 or T3 multiplexers. Frame relay is a connection-oriented interface that initially will be incorporated into private T1 and T3 multiplexers. While some carriers have committed to offer public frame relay service, others consider frame relay to be an "interim technology" and are focusing on cell relay (see BISDN below). T1 and T3 multiplexers equipped with frame relay will provide a packet-oriented, HDLC-framed interface to routers and X.25 packet switches. The packets will be routed to the proper destination by the multiplexers. Minimal protocol processing enables frame relay multiplexers to achieve high throughput. Initially, permanent virtual circuits will be supported; later, it is likely that switched virtual circuits services may also be provided by frame relay. The major advantage of frame-relay-equipped multiplexers is that only a single connection is required from the customer premises equipment (routers or X.25 packet switches) to the multiplexer. Also, with frame relay support in multiplexers, users contend for bandwidth
provided via the multiplexer, and thus line cost efficiencies can be improved
Frame StoreA video storage and display technique where a single frame of video is digitized and stored in memory for retrieval and subsequent display or processing. An
electronic device used to store still pictures; a highly sophisticated slide projector used to insert pre-produced still materials into a live production for visual enhancement. The graphic material can be words, graphs, quotes, or photographs
Frame to Frame DifferencingCompression technique which encodes only the information that represents the difference between successive frames
FranchiseAuthorization issued by a municipal, county, or state government entity which allows the construction and operation of a cable television system within the bounds of its governmental authority. The franchise area is the geographical area specified by a franchise where a cable operator is permitted to provide CATV service
Freenet An organization whose goal it is to provide free Internet access in a specific area, often by working with local schools and libraries. The first and preeminent example is the Cleveland Freenet. Freenet also refers to the specific Freenet software and the information services that use it
Freeze Frame VideoFreeze frame video is one frame of video, saved as an electronic slide. It can be transmitted by video over a network or saved in a video effects generator to display when it is needed to illustrate a concept
FreewareSoftware that doesn't cost anything. It can be distributed freely. However, the author still holds the copyright which means that the software can't be modified.
Freeze FrameRepeating or holding one frame so that it appears that the action has stopped
FrequencyThe 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 Modulation: The range of frequencies within which an audio device will function
FTP - File-transfer ProtocolA system for transferring files across the Internet. Anonymous FTP is a conventional way of allowing you to sign on to a computer on the Internet and copy specified public files from it. Some sites offer anonymous FTP to
distribute software and various kinds of information. You use it like any FTP, but the username is "anonymous". Many systems will allow any password and request that the password you choose is your userid. If this fails, the generic password is usually "guest
Full Duplex Audio ChannelAn audio channel which allows conversation to take place interactively and simultaneously between the various parties, without electronically cutting off one or more participants if someone else is speaking. With a Half Duplex Audio Channel, only one party can speak at a time without cutting off the other end. Full-motion Video: Not compressed. A standard video signal of 30 frames per second, 525 horizontal lines per frame, capable of complete action
Fully Interactive Audio/VideoTwo or more video conferencing sites can interact with
one another via audio and video signals. Two sites may be fully interactive without necessarily being full-motion sites


GLOBAL POSITIONING SYSTEM (GPS)A US satellite system that lets those on the ground, on the water or in the air determine their position with extreme accuracy using GPS receivers.
GainAn increase in signal power in transmission from one point to another; usually expressed in decibels
GatewayA machine that exists on two networks, such as the Internet and BITNET, and that can transfer mail between them
GatewayA network element (node) that performs conversions between different coding and transmission formats. The gateway does this by having many types of commonly used transmission equipment to provide a means for interconnection
GB - GigabyteA unit of data storage size which represents 2^30 (over 1 billion) characters of information
Gb - Gigabit2^30 bits of information (usually used to express a data transfer rate; as in, 1 gigabit/second = 1Gbps)
Generational LossReduction in picture quality resulting from copying video signals for
editing and distribution
GenlockAbility of a device that handles video signals to synchronize itself to an external signal, as for overlaying graphics onto the incoming signal
Geostationary Orbit - Geosynchronous - Clarke BeltAn orbital path approximately 22,300 miles above the earth. This unique satellite orbit has the characteristic that objects located in it rotate at the same relative speed as the surface of the earth. Objects placed in this orbit such as communications satellites can be considered fixed with respect to antennas located on the surface of the earth which are oriented towards
them. Satellites in this orbit are always positioned above the same spot on the earth and
from the earth, they appear fixed in space. Microwave transmission from these earth
located antennas can be sent to the relatively fixed satellites in this orbit which serve as microwave repeaters back to the surface of the earth. British physicist and science fiction writer, Sir Arthur C. Clarke, invented satellite communication in his 1954 paper Wireless World, which explained this east-west orbit, 22,300 miles above the equator; three satellites based in this orbit could provide world-wide communications
Get a lifeWhat to say to somebody who has spent too much time in front of acomputer
Ghz - GigaHertzSee Hz - Hertz
Glass MasterA highly polished glass disc, coated with photoresist and etched by a laser beam, that is used at the start of the compact disc manufacturing process
GIF - Graphic Interchange FormatA format developed in the mid-1980s by CompuServe for use in photo-quality graphics images. Now commonly used everywhere on-line. The filename extension generally given to GIF files is .gif
Glitch1. A narrow horizontal bar moving vertically through a television picture. 2. A short duration pulse moving through the video signal at approximately reference black level on a wave-form monitor. 3. A random error in a computer program. 4. Any random, usually short, unexplained malfunction
GNU - Gnu's Not UnixA project of the Free Software Foundation to write a free version of the Unix operating system
Gopher and Gopher ServerAn Internet information retrieval system. Software following a simple protocol for tunneling through a TCP/IP Internet, and running errands, especially the retrieval of "documents." This information system is technically known as
a Gopher Server and is part of an international network of Gopher Servers. The Gopher concept was created and initially implemented at the University of Minnesota. The software they created has migrated around the Internet and is now serving the public at large. Since its initial conception, many other organizations have contributed software to this effort
Graphics Visual data. This includes photographs, line drawings, computer-generated artwork, and graphs. Graphics can be entered into the computer using scanners, drawing programs, cameras, and graphics tablets
Green BookThe specification for the CD-I standard. See CD-I
GroupwareGroupware is an interactive collaboration of workers or students via networked applications on the computer. It provides audio, video conferencing and data sharing among a group of users using the network at the same time. Examples of programs/equipment that foster the concept of groupware is CLI's Cameo, Northern
Telecom's Visit, and IBM's Person-to-Person
GUI - Graphical user interfaceThe underlying principle of client/server computing is empowerment of the end-user through the delivery of information services to the desktop. Services are delivered across the network to a graphical user interface where data is massaged, merged, and maximized. GUIs are designed to juggle multiple applications in windows, through icon-driven commands that standardize application usage and optimize the underlying flow of information across the network


HIGH DEFINITION TELEVISION (HDTV)An improved television system which provides approximately twice the vertical and horizontal resolution of existing television standards. It also provides audio quality approaching that of compact discs.
H.261CCITT standard for video compression. It is used to transmit video at rates between 64 Kilobits per second and T1 speeds. It is also referred to as Px64. Px64 supports intra-coded frames (JPEG-like compression techniques) or "p-frames" (predictive frames, typical of temporal compression and decompression techniques like MPEG). Px64 is an evolving multi-dimensional video telephone conferencing standard that defines compression of audio and motion video images at resolutions of 288 lines by 360 pixels or 144 lines by 180 pixels. Complying with the CCITT's recommendation H.261 Px64 incorporates multiplexing, demultiplexing and framing of multimedia data, as well as transmission protocol and bandwidth congruence, and call setup and teardown. Px64 supports intra-coded frames (JPEG-like compression techniques) or "pframes (predictive frames, typical temporal compression and decompression techniques like MPEG)
H.323 Series StandardThe H.323 standard provides a foundation for audio, video, and data communications across IP-based networks, including the Internet. By complying to H.323, multimedia products and applications from multiple vendors can interoperate, allowing users to communicate without concern for compatibility. H.323 is the keystone for LAN-based products for consumer, business, entertainment, and professional applications. These networks dominate corporate desktops and include
packet-switched TCP/IP and IPX over Ethernet, Fast Ethernet and Token Ring network technologies. The standard is broad in scope and includes both stand-alone devices and embedded personal computer technology as well as point-to-point and multipoint conferences. H.323 is part of a larger series of communications standards that enable videoconferencing across a range of networks. Known as H.32X, this series includes H.320 and H.324, which address ISDN and PSTN communications, respectively. H.323 applications include desktop videoconferencing, Internet telephony and video telephony, collaborative computing, network gaming, business conference calling, distance learning, support and help desk applications and interactive shopping
Hacker On the NetUnlike among the general public, this is not a bad person; it is simply somebody who enjoys stretching hardware and software to their limits, seeing just what they can get their computers to do. What many people call hackers,
net.denizens refer to as crackers
Half-DuplexA communications channel over which both transmission and reception are possible but only in one direction at one time; e.g., a two-wire circuit
HandshakeTwo modems trying to connect first do this to agree on how to transfer data
HandshakingExchange of predetermined signals when a connection is established between two data-set devices
HangWhen a modem fails to hang up
Hard Copy1. Any physical document. 2. Computer printout on permanent media such as paper
Hard-WiredThe direct local wiring of a terminal to a computer system
HardwareCollectively, electronic circuits, components and associated fitting and attachments. The physical parts, components and machinery associated with computation
Hayes CompatibleDescribes modems that are compatible because they respond to the same set of commands as a modem manufactured by Hayes Microcomputer Products. This has become the standard for microcomputer modems
HDSL - High-Bit-Rate Digital Subscriber LineA method of providing high-speed data services over unconditioned copper wires at a top speed of 1.544 mbit/s. VHDSL (for very high-bit-rate digital subscriber line) is double that at 3 mbit/s. The key advantage of HDSL and VHDSL is that they allow telcos to provide services like frame relay, SMDS, and high-quality compressed video over existing telephone lines which is much less expensive than pulling fiber or installing additional repeaters. VHDSL is based on carrierless amplitude/phase modulation (CAP) and has applications beyond HDSL and VHDSL such as a video-on-demand service (being tested by Bell Atlantic) using CAP in which subscribers can interactively request videos, which are then transmitted over high-speed lines
HDTVHigher (than normal) definition TV. HDTV is generally defined as a system that offers, as a minimum, certain specific features and characteristics. These are Wide aspect ratio (now agreed as 19:9 or 1.778:1.; effectively doubled horizontal and vertical resolution (compared to existing systems); absence of encoding/decoding artifacts (requires component operation); and compact disc quality stereo sound. The technology applied to make HDTV transmittable in existing 6 MHz channels is essentially the same as the technology necessary for multichannel operation in those same channels
HeadendElectronic control center that receives and re-transmits broadcast TV signals or original signals to receiving locations in a cable system or satellite network. A system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors and other related equipment
HeaderThe part of an e-mail message or Usenet posting that contains information about the message such as who its from, when it was sent, etc. Helical Recording Format: A recording format in which the tape is unwrapped around a cylindrical scanning assembly with one or more recording heads
HFS - Hierarchical File SystemUsed on the Macintosh platform for directory structure. The hierarchical directory structure allows a volume to be divided into smaller units known as directories and, in turn, sub-directories. The hierarchical directory structure uses a graphical metaphor of folders containing files or additional folders. Macintosh interface elements, like color icons, are embedded with file structure information
High BandThat portion of the electromagnetic spectrum from 174 to 216 MHz, where television channels 7 through 13 are located
High Sierra FormatThe original format proposed by the High Sierra Group for organizing files and directories on CD-ROM. A revised version of this format was adopted by the International Standards Organization as ISO 9660
High Sierra GroupAn ad hoc group of CD-ROM researchers and developers who first gathered at the High Sierra Hotel in Lake Tahoe, CA, to propose a standard CD-ROM file format. This proposal was later amended and approved as the ISO 9660 standard for CD-ROM
Hollywood SyndromeTendency to base ones video behavior on a model that includes a highly polished presentation rather than interaction and the use of fast-paced visuals for effect rather than substance
Holy WarArguments on the Internet that involve certain basic tenets of faith, about which one cannot disagree without setting one of these off. For example: IBM PCs are inherently superior to Macintoshes or Macs are inherently superior to IBMs
Homes PassedThe number of living units (single residential homes, apartments, condominium units) passed by cable television distribution facilities in a given cable system service area
Homogeneous NetworkA network of similar host computers such as those of one model of one manufacturer
Horizontal BlankingThe blanking signal at the end of each scanning line that permits the return of the electron beam from the right to the left side of the raster after the scanning of one line
Horizontal ResolutionThe maximum number of black and white vertical lines that can be resolved within a horizontal expanse of raster equal to one picture height. NTSC television pictures normally have 300 lines of resolution or less
Horizontal RetraceThe return of the electron beam from the right to the left side of the raster after the scanning of one line
Host SystemA public-access site; provides Internet access to people outside the research and government community
HostsComputers (not terminals) that process data, act as data sources or destinations in a communications network
.hqxThe filename extension used for BinHex files
HTML - HyperText Markup LanguageThe language used to mark up text files with links for use with World Wide Web browsers. This is a file format, based on SGML, for hypertext documents on the Internet. It is very simple and allows for the embedding of images, sounds, video streams, form fields and simple text formatting. References to other objects are embedded using uniform resource locators (URLs)
HTTP - Hypertext Transfer ProtocolThe Internet protocol, based on TCP/IP, used to
fetch hypertext objects from remote hosts. See also TCP/IP
Hub1. A signal distribution point for part of an overall system. 2. The master station through which all communications to, from and between micro terminals must flow
HueThe attribute of color perception that determines whether the color is red, yellow, green, blue, purple, etc
HyperbandThe band of cable television channels above 300 MHz
HypermediaSoftware that allows the user to interactively manipulate text, images, animation, graphics, sounds, digitized voice, and video
HYTELNETStands for HyperTelnet. HYTELNET is essentially a database of Telnet sites and other Internet resources that can link to other programs when you want to connect to a site you've found. Not as useful as Gopher. A system that provides access to libraries around the world through the Internet
Hz - HertzBasic measure of frequency with which an electromagnetic wave completes a full cycle from its positive to its negative pole and back again. Hertz is a unit of frequency equal to one cycle per second. Normal house current is 60 Hertz (60 cycles per second). kHz - Kilohertz: 1,000 Hertz MHz - Megahertz: 1,000 kHz-one million Hertz GHz - Gigahertz: 1,000 MHz-one billion Hertz


INTERACTIVE VIDEO DATA SERVICE (IVDS)A communication system, operating over a short distance, that allows nearly instantaneous two-way responses by using a hand-held device at a fixed location. Viewer participation in game shows, distance learning and e-mail on computer networks are examples.
INSTRUCTIONAL TELEVISION FIXED SERVICE (ITFS)A service provided by one or more fixed microwave stations operated by an educational organization and used to transmit instructional information to fixed locations.
IAB - Internet Architecture BoardThe coordinating committee for Internet design, engineering and management
ICNIowa Communications Network
IconA pictorial, symbolic representation of a function or task. Used in GUIs (Graphical User Interfaces) such as Windows and Apple Macintosh Finder. See GUI
IEEEInstitute of Electrical and Electronic Engineers
IETFInternet Engineering Task Force
IHE - Institution of Higher EducationA postsecondary educational institution college, university, and other such schools
IMIntermodulation distortion occurs when two or more signals are passed through a nonlinear device such as an amplifier
IMAPA new protocol for the storage and retrieval of e-mail. Much like POP - the Post Office Protocol
InboundThe direction of a signal relative to the hub of a local area network (LAN) or other telecommunications system. Inbound signals would be traveling from originating points other than the primary hub in the reverse direction to the hub. Information Agent: A software program (currently only an interface to frequently updated databases) that can search numerous databases for information that interests you without your having to know what it is searching. Archie and Veronica are current examples of information agents
InfraredThat portion of the electromagnetic spectrum just below visible light; infrared radiation has a wavelength from 800 nm to about 1mm. Fiber-optic transmission is predominantly in the near-infrared region, about 800 to 1600 nm. Initialization: The process carried out at the commencement of a program to test that all indicators and constants are set to prescribed conditions
IntelsatThe International Telecommunications Satellite Organization operates a network of satellites for international transmissions. The stated purpose is the design, development, construction, establishment, maintenance, and operation of the space segment of the global communications satellite system
InteractiveAny application that allows the participants at distant locations to communicate with each other; may indicate two-way video and two-way audio; one-way video and two-way audio through a normal telephone call placed to the origination site; asynchronously (not in real time) as through computer conferencing such as an electronic mail system; or through interaction with a teaching machine such as a Telecommunications Glossary/43 computer which is programmed to respond to the user with messages on the screen, voice or other sounds to indicate that an answer is right or wrong
Interactive TechnologyInteractive Technology
Interactive TelevisionLets owners of ordinary TVs order movies, home shopping, mutimedia packages and other digitized products from electronic jukeboxes
IMHOInternet shorthand for "In my humble opinion
Instructional DesignThe methodology used to deliver information in a manner that achieves learning
Integrated Circuit - ICAn electronic circuit made by manipulating layers of semiconductive materials
Integrated SystemA system in which all components including the various types of amplifiers and taps have been designed from a well-founded overall engineering concept, to be fully compatible with each other. Interactive: The active participation of the user in directing the flow of the computer or video program
Interactive videoThe capability to transmit and receive two-way video transmissions between two or more sites
Interactive Cable SystemA two-way cable system that has the capability to provide a subscriber with the ability to enter commands or responses on an in-home terminal and generate responses or stimuli at a remote location. An example of an interactive system would be order entry for Pay-Per-View the order information is transmitted upstream on the cable from the subscriber's terminal to the headend, processed by a billing/authorization computer, and authorization to view a specific Pay-Per-View event is sent downstream to the subscriber's terminal
Interactive MultimediaA multi-level multimedia presentation that allows you to access information randomly and nonsequentially
InterconnectThe connection of two or more cable systems. 2. The connection of a headend to its hubs
Inter-Exchange Carrier - IXCCarriers that can carry inter-LATA traffic. Long distance telephone companies such as AT&T, MCI, and US Sprint
InterfaceThe link between two pieces of disparate equipment, such as a CPU and a peripheral device. Also, a method of translating data from computer to user. For Internet, the user interface is difficult for the uninitiated to use. Software programs have been written which change the look of the screen by provide pull-down menus, buttons, hierarchical files folders or hypertext to use and move around the Internet. Software program names include Mosaic, Lynx, Internet in a Box and GINA
InterferenceA scrambling of the content of signals by the reception of desired signals
Interlaced VideoProcess of scanning video frames in two passes, with each pass painting every other line of the frame onto the screen. NTSC's 525-line frame scans in two fields of 262.5 lines each that take 1/60 second to paint; a frame takes 1/30 second to paint. Noninterlaced video scans complete video frames in one pass usually producing a higher image quality
InterleaveA method of storing information in an alternating sequence of frames
International Telecommunication Union - ITUOrganization composed of the telecommunications administrations of the participating nations. Focus is the maintenance and extension of international cooperation for improving telecommunications development and applications
InternetA worldwide system for linking smaller computer networks together - governmental institutions, military branches, educational institutions, and commercial companies. Networks connected through the Internet use a particular set of communications standards to communicate, known as TCP/IP. Internet is the name given to the overall connectivity of all its various sub-networks, including USENET, APRAnet, CSnet, BITNET, etc. There is no surcharge to send or receive messages through Internet. Only ASCII messages up to 50,000 characters can be sent through this system. With a lowercase "i", an internet is a group of connected networks
InterSLIPA free program provided to the Macintosh Internet community by InterCon Systems. In conjunction with MacTP, InterSLIP enables users with modem and a SLIP account to use excellent software like Fetch and TurboGopher
IntranetIntranets differ from the Internet because they are private networks, set off from the rest of the world by firewalls. They can often connect disparate corporate networks. They often access corporate resources and databases that were built with non-Internet technology in mind
IP - Internet ProtocolThe main protocol used on the Internet
IRC - Internet Relay ChatA service where users can "talk" via typing to people around the world
IridiumMotorola's $3 billion worldwide direct cellular project which will enable users to have one worldwide number. This will be accomplished by a system of low earth orbiting satellites (LEOs)
ISDN - Integrated Services Digital NetworkA set of standards provide a common architecture for the development and deployment of digitally integrated communications services. A set of standardized customer interfaces and signaling protocols for delivering digital circuit-switched voice/data and packet-switched data services. ISDN is designed to provide standard interfaces to custom premises equipment such as computers, telephones, and facsimile machines through basic rate interface (BRI) to PBXs, host computers, and LANs through primary rate interface (PRI); to the pubic Telecommunications Glossary/45 switched network through SS7; and to local packet data terminals and the public packet-switched network through X.25 and X.75/X.75' packet services. The key to ISDN is out-of-band signaling which permits the users' equipment and the network to exchange control and signaling information over a separate channel from that which carries user information. A digital telecommunications channel that allows integrated transmission of voice, video and data. ISDN lines used to access network services are divided into bearer, or "B" channels, and a supervisory, or "D" channel, for out-of-band signaling. B Channels carry digitally encoded customer information such as voice and data traffic, while the D channel provides the information required to set up, route and disconnect calls on B Channels. D channels can also carry other information such as caller identification. Twenty-three B channels and one D channel form a Primary Rate Interface or "23B+D". PRI B channels can be used for any combination of voice, data, and image transmission at 64 kpbs. In addition, B channels can be grouped together to create wider bandwidths for applications like video transmission.
ISOInternational Standards Organization
ISO 9660The international standard for directory structures and file layout on CDROMs, a logical, structural standard compared to the physical standards for manufacturing called the "Yellow Book." This standard specifies, for single sessions, exactly how information is stored on a CD-ROM to be accessible in any CD-ROM drive running on a variety of common operating systems
ISOC - Internet SocietyISOC is a membership organization that supports the Internet and is the governing body to which IAB reports
ITFS Antenna System - Instructional Television Fixed ServiceLocal (up to 25-mile radius) one-way, over-the-air block of TV channels operating at microwave (very high) frequencies reserved for educational purposes; can be received only by TV installations equipped with a converter to change signals back to those used by a TV set. One-way audio and full motion video. The antenna may be omnidirectional or shaped to cover a specific geographic area. In rare instances the ITFS antenna system can be found to be very directional for special repeater applications or to serve a series of co-linear receive sites. The ITFS television transmission system was first authorized in 1963 by the FCC for educational television in the 2.5 to 2.686 GHz band. The ITFS band has subsequently been re-allocated for shared operation among multipoint distribution services, multichannel multipoint distribution services, operational fixed services, and ITFS users
IVDS - Interactive Video and Data ServicesName for license which will be granted by the FCC to devices called Interactive TV Appliances (ITAs). ITAs include TVAnswer, a two-way television service for consumers for game shows, sporting events and respond instantly to news polls and interactive advertising as well as participate in distance learning. The system will also let viewers shop, bank, pay bills, organize TV programming and order a pizza
IVRThe IVR unit answers the call, greets the caller, and guides the caller through possible responses with a series of voice prompts. The desired information is provided via prerecorded voice fragments (words) or computer-generated speech


JackA connecting device to which a wire or wires of a circuit may be attached and which is arranged for the insertion of a plug
JANET - Joint Academic NetworkJANET is Great Britain's national network. JANET addresses work backwards from normal Internet addresses (largest domain to the smallest). Mot gateways to JANET perform the necessary translations automatically
Janus discA CD-ROM that contains data tracks in two or more different formats, such as ISO 9660 and HFS (Macintosh Hierarchical File Structure)
JavaJava is similar to the C++ computer language that is already used by many programmers, and it is object-oriented so that new applications can be built from preexisting components. It is a compiled language, so that after it is written, it must be run through a compiler to allow computers to understand it. But - only one compiled version is created which can run on many different platforms (where other languages require a different version for each platform). Java can be used to tap into and "mine" databases or create interactive multimedia applications. A common use of Java is to create a news ticker broadcasting the latest news that people can click on to get more details
Java AppletA program written in Java to run within a Java-compatible web browser, such as HotJava or Netscape Navigator
Java PlatformThe Java Virtual Machine and the Java core classes make up the Java Platform. The Java Platform provides a uniform programming interface to a 100 percent pure Java program regardless of the underlying operating system. When implemented on a particular operating system, the Java Platform is said to be Java Compatible if it passes the Java Compatibility Kit suite of tests
JPEG - Joint Photographic Expert GroupJPEG is an industry standard for stillimage compression that is moving into full-motion video. Storing the video signal is a problem as it takes a 300 megabyte hard disk to store just 10 seconds of digital video. Compression is the answer to storage problems. JPEG is a compression technique based upon intraframe encoding technology. It allows full restoration of symmetrically compressed images. Symmetrical compression means that the image takes an equally long time to be compressed as it does to be decompressed. An asymmetrical scheme takes longer to compress an image than to decompress it and typically compresses the image on a computer other than the one to be used for decompression. Relying on a newly adopted format to encode and decode digital images based on independent, nontemporal (intraframe) data, JPEG typically divides an image into 8 by 8 pixel blocks. These 64 square pixel matrices, called a "search range," enable the aggregate quantization of the image and color data store by the pixels within each of the blocks. Advanced JPEG algorithms that use larger search ranges, up to as much as 32 by 32 pixels, called "super blocks," enable significantly faster encoding and decoding (up to 40 to 1 compression at about 4MB per second) but demand exponentially more processing power to maintain the same degree of image quality as the smaller pixel block. Originally, JPEG was intended to compress only still images. However, video is nothing more than a quick presentation of successive still images. Thus, a form of JPEG, known Telecommunications Glossary/47 commonly as motion JPEG, is being used to compress motion images, particularly in applications like video editing where it is necessary to access individual frames of video and to scrub forward and backwards through source material. JPEG, MPEG and Px64 specifications use a Discrete Cosine Transform (DCT), an encoding algorithm that quantifies the human eye's ability to detect color and image distortion. DCT parses color content data thereby enabling the use of a higher pixel depth sampling rate (typically 24 or 32 bits) than non-DCT compression techniques. JPEG typically controls 24 bits per RGB pixel, retaining a high quantization of luminance and color resolution
JPEG System HighlightsUsed to encode still images. It compresses about 20 to 1 ratio before visible image degradation occurs. Compression ratios exceeding 100 to 1 attainable but image degrades excessively. At very low compression ratios of 5 to 1 maximum JPEG maintains absolute resolution. It excludes audio compression. Symmetrical (compresses at same rate as it decompresses,) uses the same hardware to encode and decode. It compresses redundant data occurring within each frame (intraframe). Compresses comparatively slow, depending on computer speed, about 1 to 3 seconds for a 1 MByte image. Decompresses a full sized image in .5 to 1 second or reduced sized image in real time. It has good quality at maximum compression. Jukebox: CD-ROM drive with a disc changing mechanism, capable of playing multiple discs


Ka-BandA satellite transmission in the 20 and 30 gigahertz frequency spectrum. Kbps, kb/s - Kilobits per Second: A unit of measure of data of 1,000 bits per second or 1,000 Baud
KermitA file transfer protocol named after Kermit the Frog. Kermit is generally slower than XMODEM, YMODEM, and ZMODEM
KerningReducing the horizontal space between characters of type. Originally, casting a letter so that part of it (e.g., the top of the f) extends beyond the body of the letter, into the space occupied by the next letter. Sometimes used to mean adding or removing space between letters
KeyboardAn alphanumeric, input/output, peripheral device used to communicate with a computer
KillfileA file that lets you filter Usenet postings to some extent, by excluding messages on certain topics or from certain people
KilobaudThe measure of data transmission speed a thousand bits per second
KilobyteA unit of measurement equal to 1024 bytes
Kine RecordingThe technique of converting a video image to motion picture film
KnowbotShort for knowledge robot. Embedded machine intelligence capable of automatically and regularly searching for new information on parameters set by the user. At its extreme, the knowbot becomes an intelligent partner in mediating human communication. Sometimes called an agent
Knowledge NavigatorAn information agent popularized by an Apple video about working with computers in the future
Ku BandA category of satellite transmissions higher in frequency than those used as "c band" which are being transmitted from satellites placed in the geostationary orbit. The group of microwave frequencies from 12 to 18 GHz and the band of satellite downlink frequencies from 11.7 to 12.2 GHz. The higher frequencies (12 GHz versus 4 GHz) have created the possibility of smaller receive antennas and the realization of direct broadcast satellite (DBS) signals to the end user without the necessity of going through a cable television system or other shared use receive site due to the factors of size and cost


LANDLINETraditional wired phone service.
LAND MOBILE SERVICEA public or private radio service providing two-way communication, paging and radio signaling on land.
LOW POWER FM RADIO (LPFM)A broadcast service that permits the licensing of 50-100 watt FM radio stations within a service radius of up to 3.5 miles and 1-10 watt FM radio stations within a service radius of 1 to 2 miles.
LOW POWER TELEVISION (LPTV)A broadcast service that permits program origination, subscription service or both via low powered television translators. LPTV service includes the existing translator service and operates on a secondary basis to regular television stations. Transmitter output is limited to 1,000 watts for normal VHF stations and 100 watts when a VHF operation is on an allocated channel.
LAN - Local Area NetworkPrivate transmission network interconnecting offices within a building or group of buildings and usually designed to convey traffic; e.g., voice, data, facsimile, video. Usually associated now with a computer network made up of computers, printers, and mass storage units. MAN Metropolitan area network. WAN - Wide Area Network
Large-Scale Integration - LSIThe process of engraving many thousands of electrical circuits on a small chip of silicon
Laser - Light Amplification by Stimulated Emission of Radiation1. A device for generating coherent electromagnetic signals (e.g., light). Low powered lasers are frequently used to transmit light signals into optical fibers. 2. Laser light contains waves that have the same phase, as opposed to conventional light, whose individual wave phases are unrelated to the phases of the others
LATALocal access and transport area of a telephone company
LavaliereA small microphone that can be clipped onto clothing or suspended from neck cords and worn in front of the chest
LCD - Liquid Crystal DisplayA method of creating alphanumeric displays by reflecting light on a special crystalline substance. Frequently used in electronic games and watches, and in portable electronic instruments
LEA - Local Educational Agency(a) a public board of education or other public authority legally constituted within a state for either administrative control of, or direction of, or to perform service functions for, public elementary or secondary schools in a city, county, township, school district, or other political subdivisions of a State; or such combination of school districts or counties a State recognizes as an administrative agency for its public elementary or secondary schools; (b) any other public institution or agency that has administrative control and direction of a public elementary or secondary school; (c) as used in vocational education programs the term also includes any other public institution or agency that has administrative control and direction of a vocational education program
Leading (pronounced "ledding")Vertical space between lines of type, measured in points. In metal type, leading is the additional space (from inserting strips of lead between lines of metal type). In phototype and digital type, where there is no metal body determining the height of the type, leading has come to mean the total space from one line to the next, usually measured from baseline to baseline
Learning StylesA learner's learning style is as individual as a fingerprint. We all learn differently. The Canfield Learning Style instrument identifies styles in iconic, direct experience, listening, qualitative, numeric, and other modes. The student-centered approach to learning styles is to have the facilitator adapt his/her style to that which will meet the student's learning style. Since even a small class will present varied learning Telecommunications Glossary/50 styles, it is best to prepare materials that use a variety of technology delivery methods so that the needs of all learners are met
Leased LinesA term used to describe the leased or rented use of dedicated lines from point to point. Lines could include fiber optic cables, telephone cables, microwave or other transmission systems
LECLocal exchange carrier of a telephone company
LED - Light Emitting DiodeA semiconductor which emits light when a proper voltage is applied to its terminals
Light PenA pen-like device that contains a photosensitive cell and small aperture lens that produces or detects electronic signals; can be used to write free-hand directly on a TV screen or to enter, edit and position computer text or graphics
LinearVideo technology designed to be played from beginning to end without stops
LinksCommunication pathways between nodes
Lip SyncSynchronization of the sound portion with the visual portion of a television program
LISTSERVA powerful program for automating mailing lists
LNA - Low Noise AmplifierLocated at the antenna. Refers to electronic equipment, used in conjunction with satellite reception, intended to amplify extremely weak satellite signals without introduction of noise. They are rated in different noise temperatures, expressed in degrees Kelvin. The lower the noise temperature figure, the higher the carrier-to-noise ratio, and the better the picture
Local Exchange Carrier (LEC)Carriers that can carry only intra-LATA traffic. Local telephone companies such as US West, Contel, Centel etc
Local LoopThe local loop gets the signal from the receive site to the viewing room. Microwave, fiber optics, cable and sometimes broadcast are used to distribute the signal. Also referred to as the "Last Mile"
Location - RemoteProduction shooting site other than a studio
Log On/Log InConnect to a host system or public-access site
Log OffDisconnect from a host system
Low BandThat portion of the electromagnetic spectrum from 54 to 88 MHz, where television channels 2-6 are located
Low Earth Orbiting Satellite - LEOLow earth orbit satellites which require 77 small, smart satellites to provide linkage around the world. The satellites move overhead in Telecommunications Glossary/51 their low orbit. Motorola's Iridium (from the element Iridium which has 77 electrons) uses the concept to provide, digital, satellite-based personal communications via small, handheld transportable receivers. With the system, voice, fax, or data calls can be made or received anywhere. The user will have one universal telephone number for the phone. Local gateways will store customer billing information, keep track of user locations, and interconnect with terrestrial carriers worldwide. The dual-mode phone will access customers' regular cellular service first, switching to Iridium only when there is no terrestrial signal, to assure least-cost routing. The system is planned to be launched in 1994 with service by the end of 1996. Inmarsat's Project 21 will provide similar services.
LPTV - Low Power TelevisionBroadcast medium that is similar to commercial TV but limited in broadcast coverage area by its low power signal. Can air one class per time frame which can be received at multiple sites
LumenUnit of light flux
Luminance1. Luminous flux emitted, rejected, or transmitted per unit of solid angle per projected area of the source. 2. The photometric equivalent of brightness. 3. The brightness part of a television picture
Luminance SignalThat portion of the television signal which conveys the luminance or brightness information
Lurk - Lurkers - LurkingPeople who read messages in a Usenet newsgroup or other public system without ever responding or contributing to the topic
LuxUnit of n equal to 1 lumen per square meter or approximately 0.1 candle power


MUST-CARRY (Retransmission)A 1992 Cable Act term requiring a cable system to carry signals of both commercial and noncommercial television broadcast stations that are "local" to the area served by the cable system.
MacBinaryA file format that combines the three parts of a Macintosh file; the data fork, the resource fork, and the Finder information block. No other computers understand the normal Macintosh file format, but they can transmit the MacBinary format without losing data. When you download a binary Macintosh file from another computer using the MacBinary format, your communications program automatically reassemble the file into a normal Macintosh file
Machine LanguageBinary code that can be directly executed by the processor, as opposed to assembly or high-level language
MacTCPA Control Panel from Apple that implements TCP on the Macintosh. MacTCP is required to use programs such as Fetch and TurboGopher
Magnetic MediaAny medium on which data is stored as variations in magnetic polarity. Usually floppy disks, hard disks, and tape
Magnetic TapeA mylar tape, coated with magnetic particles, on which audio, video or data can be stored
Mailing ListEssentially a conference in which messages are delivered right to your mailbox, instead of to a Usenet newsgroup. You get on these by sending a message to a specific e- mail address, which is often that of a computer that automates the process
Magneto-opticalAn information storage medium that is magnetically-sensitive only at high temperatures. A laser heats a small spot, which allows a magnet to change its polarity. The medium is stable at normal temperatures. Magneto-optical discs can be erased and re-recorded
MasterThe original video tape, audio tape or film of a finished product. Usually stored in a vault or area protected from the environment. Dubs are made from the master. Once the master is worn out, it can not be replicated
Master Antenna Television System - MATVAn antenna and distribution system which serves multiple dwelling complexes such as motels, hotels, and apartments. It is, in effect, a miniature cable system
Mastering FacilityA manufacturing plant where compact disc "masters" are created for the mass production or replication of the actual compact discs. Metal Master: A metal disc created by plating an etched glass master disc with nickel. Used in a mastering facility to create metal stampers for the mass production of compact discs
MATV - Master Antenna TelevisionCentrally-located receiving system that distributes off-air signals and to multiple places in the cable transmission system
Master ControlNerve center for telecasts. Controls the program input, switching, and retrieval for on-the-air telecasts. Also oversees technical quality of programs
MatteThe keying of two scenes; the electronic laying in of a background image behind a foreground scene, such as a picture of a town meeting behind the newscaster reporting on the meeting
Matte KeyKeyed (electronically cut-in) title whose letters are filled with shades of gray or a specific color
MBONE - Multicast BackboneInternet. An outgrowth of the first two IETF "audiocast" experiments in which live audio and video were multicast from the IETF meeting site to destinations around the world. The idea is to construct a semi-permanent IP multicast testbed to carry the IETF transmissions and support continued experimentation between meetings. The MBONE is a virtual network. It is layered on top of portions of the physical Internet to support routing of IP multicast packets since that function has not yet been integrated into many production routers. The network is composed of islands that can directly support IP multicast, such as multicast LANs like Ethernet, linked by virtual point-to-point links called "tunnels". The tunnel endpoints are typically workstation-class machines having operating system support for IP multicast and running the "mrouted" multicast routing daemon
mbps, MB/s - Megabits per SecondA unit of measure of data of 1,000,000 bits per second or 1,000,000 Baud
MCC - Microelectronics and Computer Technology CorporationAn industry consortium that developed the MacWAIS software
MCU - Multipoint Control UnitMCU's have the ability to support multipoint videoconferences on codecs of the same brand and (in most cases) model
MDSPay television delivery service relayed by microwave to small dish antennas
Mean Time Between Failure - MTBFA statistical quantitative value for the time between episodes of equipment or component failure
Medium (Media)Any material substance(s) that can be used for the propagation of signals. Examples are copper, air, water, and fiber optics
Meet-Me Bridge - Meet-Me TeleconferencingA type of telephone bridge that can be accessed directly by calling a certain access number; provides dial-in teleconferencing. The term "meet-me bridging" refers to the use of this type of bridge
Mega1. Ten to the sixth power, 1,000,000 in decimal notation. 2. When referring to storage capacity, two to the twentieth power, 1,048,576 in decimal notation
MegabyteA unit of measurement equal to 1024 x 1024 bytes, or 1024 kilobytes; 8 million bits
MegaHertz - MHzOne million cycles per second
MemoryComputer's information storage capability. RAM - random access memory; ROM - read only memory
MenuA list of symbols and functions that can be selected on a computer system
MicrocomputerA relatively precise term for computers whose central processing units (CPUs) are microprocessor chips. By contrast, mainframes and most minicomputers have CPUs containing large circuitry. Microcomputers include personal computers, small business computers, desktop computers, and home computers
MicrofichA system of storing and retrieving information microforms, consisting of film in the form of separate sheets, that contain original text, pictures, data, or anything which has been reduced to micro- images for a greater storage efficiency and arranged in a grid pattern for location of those original images by means of Cartesian coordinates
MicrofilmA system of storing and retrieving information microforms, consisting of film as a data medium, usually in the form of a roll or strip, that contains micro-images of the original information. The images are generally in a sequential arrangement rather than in rows or columns as on microfiche
MicroprocessorThe heart of the computer. This is a silicon chip with the computer's central processing unit implemented on the chip
MicrosecondOne millionth of a second
Microsoft WindowsA GUI (graphic user interface) operating environment developed by Microsoft for use on PCs running under the MS-DOS operating system
MicrowaveThat portion of the electromagnetic spectrum from approximately 1,000 Megahertz to 100,000 Megahertz. The microwave energy is capable of being focused in concentrated beams in specific directions due to its short wavelength characteristics and sent over long distances. Point-to-point transmission system that transmit signals through the air using transmitters and antennas attached to tall towers. Provides program audio and video plus the capacity for additional voice and data material. It is also capable of being transmitted over wide areas from a central point or shaped into specific coverage areas with special antennas (ITFS). Extreme examples of long distance focused microwave transmissions are the signals sent from a satellite uplink earth station to a satellite 22,300 miles above the earth and from that satellite back to earth
MHz - MegahertzRefers to a frequency equal to one million Hertz, or cycles per second
MidbandThe band of cable television channels A through I, lying between 120 and 174 MHz
MIDI - Musical Instrument Digital Interface1. An industry-standard connection for computer control of musical instruments and devices. 2. Musical Instrument Digital Telecommunications Glossary/55 Interface. Industry standard for exchange of musical information between computers and musical instruments or music synthesizers
Midsplit SystemA cable-based communications system that enables signals to travel in two direction, forward and reverse simultaneously with upstream (reverse) transmission from 5 MHz to about 100 MHz and downstream (forward) transmission greater than about 150 MHz. Exact crossover frequencies vary from manufacturer to manufacturer
MIME - Multipurpose Internet Mail ExtensionsA new Internet standard for transferring non-textual data, such as audio messages or pictures, via e-mail
MinicomputerAn intermediate range computer, between full-size mainframes and 16- bit microcomputers. Historically, minicomputers have served dedicated uses, such as in scientific and laboratory work
MISManagement Information System
Mixed Mode DiscA CD-ROM that contains both CD-ROM (Yellow Book) and CDAudio(Red Book) tracks
MNPMicrocom Networking Protocol
Model1. A representation in mathematical terms of a process, device, or concept. 2. An academic model; a program with a certain set of procedures or elements which can be duplicated by others in their institutions
Modem - MOdulator/DEModulatorDevice that connects computer terminals and hosts through analog links by converting data signals to analog signals and back again. Transmission rate of 300 Baud is slow; 2400 is faster
Modem-Encryption DevicesBy placing encryption units at modem interfaces, some systems have all data on the link encrypted and decrypted in a manner that is transparent to the sending and receiving stations
ModularConstructed with standardized units or dimensions for flexibility and variety in use; allows for easy replacement, substitution, expansion or reconfiguration of modules or sub-assemblies
ModulatorA device which converts the video signal and audio signal onto a viewable TV channel. It takes the video and audio signals that are separated by the receiver and combines them into a signal that can be received by an ordinary TV set. This signal is called an "RF" signal, meaning radio frequency, and is usually set for either channel 3 or 4. The advantage of using a modulator is that it permits the use of standard TV receivers for displays, but the signal quality is not as good as using a direct video and audio feed to a monitor TV display. As with receivers, modulators should also be redundant
MonitorA television monitor is capable of projecting from an attached device such as a video tape recorder or camera; or from a cable such as that connected by cable companies or the cable from the satellite receiving unit. It is not equipped with receiver electronics which enable it to receive local broadcast channels. Studio monitors are usually high resolution so that the best possible picture is seen
MosaicA free graphical front end to the Internet that supports browsing of multimedia data that includes plain and formatted text, picture, video and sound. The data is based on the hypertext document format where text or pictures can act as links to other places in the same or different documents. Mosaic provides a simple graphical user interface (GUI) that enables easy access to the data stored on the Internet. These data may be simple files or hypertext documents. The document a user points to on the receiving desktop could be on the same machine or on another computer elsewhere on the Internet. Mosaic clients are currently available for Windows, Macintosh, the X Window System and many flavors of UNIX. Mosaic was developed by the National Center for Supercomputing (NCSA)
MOTSS - Members of the Same SexOriginally an acronym used in the 1980 federal census
MPC - Multimedia Personal ComputerA standard which describes a PC that can run Microsoft's Windows efficiently because the system software beneath multimedia would be "Windows with Multimedia Extension." The specification calls for added audio and CD-ROM hardware. MPC is a registered trademark of the MPC Marketing Council
MPEG - Moving Pictures Experts GroupMultimedia compression standard for professional and consumer applications - digital video, digital audio and systems compression. MPEG compression compresses similar frames of video, tracks elements which change between frames and discards the redundant information. This allows fullmotion video to be sent at CD-ROM data rates - around 160kbps. MPEG, which is now being called MPEG1 in some circles achieves increased compression through the use of a combination of interframe and intraframe (sometimes called MPEG 1-Frame) image and audio compression algorithms, including predictive and interpolated technologies. These techniques analyze the degree of motion present in a search range and predict the "temporal redundancy" (anticipated repetitive motion) occurring between adjacent frames. As in JPEG, pixel search blocks form the basis of the representative sampling unit. MPEG differs from motion JPEG (sometimes called "frame-rate" or motion JPEG). For frame rate JPEG to achieve the same data rates as MPEG, it must resort to bandwidth reduction strategies, such as chroma subsampling, reducing data rates either through an averaging of color information, or through decimation, which discards alternate lines or pixels of image information. The compression ratios obtainable with MPEG, which can be as high as 200 to 1 with decimation and chroma sampling, are directly dependent on the amount of data redundancy present in a given image. MPEG is designed to deliver data in the 1 to 2mbps range making it suitable for replaying full motion video stored on CD-ROMs. Telecommunications Glossary/57 MPEG2 , which is still under development, will define a compression and decompression technology suitable for delivering data at a 5 MB to 10 MB-per-second rate. It is envisioned as a data delivery system capable of delivering high-quality, high data content capacity images to computers and television. MPEG3 is projected to deliver data at a stunning (by today's standards) 60 mbps making it suitable for complex saturated color data signals, including HDTV. MPEG3 is several years away from finalization
MPEG System HighlightsUsed to encode motion images. Will deliver decompressed data in the 1.2 to 1.5 mbps range enabling CD-ROM to play back full motion color motion images at 30 frames/second. Compresses about 50 to 1 ratio before image degradation occurs. Compression ratios are as high as 200 to 1 attainable but with observable degradation, including audio compression. Asymmetrical (compresses slower than it decompresses), uses different hardware or techniques to encode and decode. Compresses redundant data appearing in sequential frames (temporal, interframe). Compression rate is fast. Decompresses in real time. Fair quality at maximum compression
MUD/MUSH/MOO/MUCK/DUM/MUSEThese are multi-user, text based, virtual reality games. A MUD (Multi-User Dungeon) is a computer program which users can log into and explore. Each user takes control of a computerized persona/avatar/incarnation/character. You can walk around, chat with other characters, explore dangerous monster-infested areas, solve puzzles, and even create your very own rooms, descriptions and items. There are an astounding number of variations on the MUD theme
Multiple System Operator - MSOAn organization that operates more than one cable television system
Multi-Link AudioAny application allowing viewers to be connected by phone (usually by audio bridge) to the spot where the broadcast originates
MultimediaThe combination of multiple digitized data types; text, sound, computergenerated graphics and animations, photographs and video. The merger of digital technologies based on the use of computers. The technologies that are converging are computing, television, printing and telecommunications
Multimedia ExtensionsAdds audio and video recording and playback capabilities to Microsoft Windows. Part of the MPC standard
MultisessionA drive that has the ability to read a CD-ROM on which data was recorded in at least two different recording sessions, or a disc that contains data recorded at different times
Multiple AccessThe ability of more than one user to use a transponder. Transponders have three basic resources frequency, time and space. The frequency domain is used in FDMA. Time domain multiple access is used in TDMA by time-sharing the transponder. Space domain multiple access makes use of either the polarization discrimination, orthogonal digital codes or through spread-spectrum techniques
Multiple Audio Subcarrier TuningEssential to take advantage of radio and data services riding piggy-back on video signals. Also, some programming may use nonstandard (6.8 and 6.2 MHz) frequencies
Multiplexor - MUXDevice that uses one of several techniques to combine multiple analog or digital signals onto a single path
MultiplexingTransmission of two or more information streams over a single physical medium at the same time such that each data source has its own channel. Allows a number of simultaneous transmissions over a single circuit. Common methods are frequency division multiplexing (FDM) where the frequency bands are split to constitute a distinct channel and time division multiplexing (TDM) where the common channel is allotted to several different information channels, one at a time
MultiprocessorA computer employing two or more processing units under integrated control
MultitaskingPertaining to the concurrent execution of two or more tasks by a computer
MANsee metropolitan area network
Mappable Geographic Informationa data file containing geocoded information in a format compatible with the MapInfo software package. French: information géographique mappable
Medium Businessn the context of business users of telecommunications services, a medium business is any commercial account whose telecom service charges generate at least $500 but less than $2500 in monthly revenue, which is equivalent to at least $6000 but less than $30 000 in annual revenue. Small businesses generate less than $500 monthly; large businesses generate at least $2500 monthly
MMS: (Multimedia Messaging Service)a wireless messaging service that adds images, text, audio clips and video clips to SMS (Short Message Service/text messaging)
Mobile Coveragethe geographic area in which a given service provider provides connectivity using a given wireless protocol such as AMPS, CDMA, CDMA 1xRTT, non-GSM TDMA, GSM, GPRS, or ESMR. Mobile coverage may be provided in one of two ways, either as an on-net service using the network managed by the service provider, or as a roaming service using a network managed by another service provider, usually due to a formal roaming agreement between the user's service provider and the mobile network operator.. Because mobile coverage often fluctuates in a given geographic zone according to climactic, architectural, and other conditions, the presence or absence of mobile coverage may be estimated according to geographic zones in which a customer might have reasonably expected outdoor coverage in at least 50 percent of the zone in question
Mobile Dataa wireless communications service involving the transmission and/or reception of data, such as SMS. Mobile data revenues include revenues accruing from Internet-based and non-Internet-based content and applications delivered as mobile data, except where those content and applications are broken out as a specific subcategory on a reporting form.
Mobile InterconnectThe linking of at least two telecommunications networks, managed separately, that allows traffic from one party's network segment to be transferred or terminated onto another party's network segment
Mobile Internet Servicea wireless communications service providing persistent or intermittent Internet access. It offers services such as news, travel, weather and entertainment using a wireless phone. Mobile Internet service revenues include flat-rate subscription revenues and recurring or volume-based usage revenues, but not revenues realized from equipment sales, nor revenues realized from the transmission of specific content or the use of specific Internet-based applications, on which see mobile data.
Mobile Switch Centre (MSC)Is a sophisticated telecommunications switch within a cellular network architecture which manages and handles circuit-switched calling and transmissions between base stations and mobile users.
Mobile Virtual Network Operator (MVNO)Is a mobile service provider who establishes arrangements with existing mobile service operator(s) to resell, pre-packaged or repacked mobile wireless service plans. The MVNO handles its own customer care, billing, marketing, and branding
ModemIs short for Modulator and Demodulator. This is a device that enables the transfer of analogue/digital signals to and from one computer device to another
Municipalityan incorporated city, county, metropolitan authority, town, village, township, district or rural municipality or other incorporated municipal body however designated. In the CRTC telecom monitoring process, Census Metropolitan Area (CMA) boundaries are preferred, but lower levels of aggregation are accepted as well. See also Census Metropolitan Area


NETWORKAny connection of two or more computers that enables them to communicate. Networks may include transmission devices, servers, cables, routers and satellites. The phone network is the total infrastructure for transmitting phone messages.
NUMBER PORTABILITYA term used to describe the capability of individuals, businesses and organizations to retain their existing telephone number(s) –– and the same quality of service –– when switching to a new local service provider.
N + 1Created by the FCC, this formula forms the basis by which the FCC regulates expansion of channel capacity for non-broadcast use. The FCC requires that if the government, education, public access, and leased channels are in use at least 80 percent of the Monday-through-Friday period for at least 80 percent of the time during any three-hour period for six consecutive weeks, then within six months the system's channel capacity must be expanded by the operator
Nanosecond - nsecOne billionth of a second
NarrowbandA telecommunications medium that carries lower frequency signals; includes telephone frequencies of about 3,000 Hertz and radio subcarrier signals of about 15,000 Hertz
NarrowcastTransmission of programs to a specifically defined audience normally using the newer technology delivery systems. Sometimes referred to as a target audience, a limited audience, or a "narrow" audience, hence the name "narrowcast."
National Cable Television Association - NCTAWashington, D.C. based trade association for the cable television industry; members are cable television system operators; associate members include cable hardware and program suppliers and distributors, law and brokerage firms, and financial institutions. NCTA represents the cable television industry before state and federal policy makers and legislators
NetThe Net-sanctioned way to refer to the Internet for the initiated
Net Computers - NCSmall computers with enough memory to navigate the Internet and download content. The Net Computers were created to close the educational gap between children in prosperous and low-income schools - usually called the haves and have-nots. Net computers will work in schools, homes, small business and other sites
Net.godOne who has been on-line since the beginning, who knows all and who has done it all
Net.personalitySomebody sufficiently opinionated/flaky/with plenty of time on his/her hands to regularly post in dozens of different Usenet newsgroups, whose presence is known to thousands of people
Net.policeDerogatory term for those who would impose their standards on other users of the Internet. Often used in vigorous flame wars (in which it occasionally mutates to net.nazis)
NetiquetteA set of common-sense guidelines for not annoying others
Network1. Two or more information sources or destinations (points or nodes) linked via communications media to exchange information. 2. It can be as simple as a cable strung between two computers a few feet apart or as complex as hundreds of Telecommunications Glossary/60 thousands of computers around the world linked through fiber optic cables, phone lines and satellites
Network ArchitectureA set of design principles, including the organization of functions and the description of data formats and procedures, used as the basis for design and implementation of a user- application network
Network Interface CardAlso known as NIC. Add-in circuit board that allows a PC to be connected to a local area network (LAN). Network License: A license from a software vendor that allows an application to be shared by many users over a network
NewbieSomeone who is new to the Internet. Sometimes used derogatorily by Net.veterans who have forgotten that, they, too, were once newbies who did not innately know the answer to everything. "Clueless newbie" is always derogatory
NewsgroupA Usenet conference
NewsreaderA program to read news and providing capabilities for following or deleting threads
NFS - Network File SystemA network service that lets a program running on one computer use data stored on a different computer on the same Internet as if it were on its own disk
NIC - Network Information CenterAn organization which provides network users with information about services provided by the network. As close as an Internet- style network gets to a hub; it's usually where you'll find information about that particular network
NII - National Information Infrastructure, Data Highway, Information HighwayAn interoperable linking of all networks for business, government, education and consumer uses. Much of the highway already exists in phone lines, coaxial cable, satellites, and cellular networks, and already functions as the Internet. The difference between the Internet and the future NII is primarily based on more bandwidth, faster operating systems, intelligence in data routing, security for all services which are conveyed through audio, data, and video modes
NNTP - Net News Transport ProtocolA transmission protocol for the transfer of Usenet news
NOC - Network Operations CenterAn organization that is responsible for maintaining a network
NodeAn addressable unit in a network, which can be a computer, work station or some type of communications control unit
Noise - AudioUnwanted sounds (static) that interfere with the intended sounds; or unwanted sound signals
Noise TemperatureThe amount of thermal noise present in a system, expressed in degrees Kelvin. The lower the noise temperature, the better
Noise - VideoUnwanted electronic interference that shows up as snow
Non-Composite Video SignalA signal which contains only the picture signal and the blanking pulses
NOSNetwork operating system
NREN - National Research and Education NetworkCreated by an act of Congress, this new network - still in interim stages - is replacing Internet as the national e-mail system connecting research, governmental, and high education networks and data bases. There is concern among some educators that K-12 will not have easy or immediate access to NREN as it's implemented
NSA line eaterThe more aware/paranoid Net users believe that the National Security Agency has a super-powerful computer assigned to reading everything posted on the Net. They will "jokingly" refer to this line eater in their postings. Goes back to the early days of the Net when the bottom lines of messages would sometimes disappear for no apparent reason
NSF - National Science FoundationFunds the NSFNet, a high-speed network that once formed the backbone of the Internet in the US
NTSCNational Television System Committee; defined the 52 5-line color video signal frequency spectrum which extends from 30 Hz to 4.2 MHz. NTSC video consists of 525 interlaced lines, with a horizontal scanning rate of 15,734 Hz, and a vertical (field) rate of 59.94 Hz. A color subcarrier at 3.579545 MHz contains color hue (phase) and saturation (amplitude) information. 30-frame-per-second color TV standard in use in U.S., Canada, Mexico, Japan and a few other countries
NASnetwork access service ; referring to the definition of NAS, a NAS-equivalent is also a wireline connection from a customer location to the PSTN. It also includes a telephone number and a connection to the PSTN but, access from the customer's location to the service provider's office utilizes a broadband Internet access. As the provider of NAS-equivalent does not inherently include the access with the service, this is also characterized as an access-independent service. NAS-equivalent is quantified by measuring the total primary telephone numbers in service counted in the exchange that is native to the primary telephone number
Network Layerlayer three in the OSI reference model. The network layer performs network routing and forwarding, flow control, segmentation/desegmentation, and error control functions, cobbling various data links together so as to enable data to be delivered between any two nodes on the interconnected data links. IP is an example of a network layer protocol
Network Segmenta network link connecting two interfaces, regardless as to whether the two interfaces interconnect switching equipment, transmission equipment, terminal equipment, or other facilities, and regardless as to whether the network link is achieved through a physical medium, through radio frequencies, or otherwise


OPEN VIDEO SYSTEMSAn alternative method to provide cable-like video service to subscribers.
OPERATOR SERVICE PROVIDER (OSP)A common carrier that provides services from public phones, including payphones and those in hotels/motels.
OEMOriginal equipment manufacturer
Off-LineMode of operation in which terminals, or other equipment, can operate while disconnected from a central processor. Contrast with "on-line" where there is a direct connection to a host computer
Off-Premises SystemRefers to a teleconferencing room or equipment located outside of a user organization's facility; e.g., a video teleconferencing room operated by a vendor and available to the public for a fee
On-Demand BandwidthDialable digital bandwidth access using the public switched telephone network instead of dedicated facilities
On-lineWhen a computer is connected to an on-line service, bulletin-board system or public-access site, it is on-line
Operating SystemA computer program that runs the computer and handles data traffic between the disks and memory
One-Way Video, Two-Way AudioPeople at originating location can be seen and heard by participants at other locations. The people at the originating location can hear, but cannot see participants at other locations. With two-way video, each group can see and hear other groups. Usually limited to point- to-point
Open Systems Interconnect - OSI:Generally open systems and networks are based on standards and the OSI model, providing applications and data portability, providing interoperability between systems, having common user interfaces, providing transparency below the application level, and provided by multiple sources, with multiple sources having input on development
Optical Character Recognition - OCRThe machine identification of printed characters through use of light-sensitive devices; often used as a method of entering data
Optical FiberAn extremely thin, flexible thread of pure glass able to carry one thousand times the information possible with traditional copper wire. See Fiber Optics
Orange BookColloquial name of the standard that describes CD-Recordable equipment, media and formats. An extension of the "Yellow Book" standard which includes specifications for incremental writes or multiple sessions. It specifies standards for CD-R and magneto-optical cartridge systems as well as Kodak's Photo CD. Most CD-ROM drives today can only read "single session" discs or the first session of a multisession disc
Origination SiteThe location from which video and/or audio is transmitted and uplinked in a teleconference. Other sites participating are receive sites
OutboundDirection of a signal relative to the hub of a local area network (LAN) or other telecommunications system. Outbound signals would be traveling away from the primary hub in the forward direction to the extremities of the system
Off-Net (mobile)not served, or not able to be served, using a given service provider's facilities. A call originating (or terminating) off-net has originated (or terminated), not on the network managed directly by the subscriber's service provider, but on another service provider's network. The latter provider usually bills the former provider for roaming or for service resale on a wholesale basis; the subscriber's provider, in turn, usually bills the end user on a retail basis
On-NetServed, or able to be served, using a given service provider's facilities. A call originating (or terminating) on-net has originated (or terminated) on the subscriber's service provider's managed network
On-Net Buildinga building containing switching equipment and/or an access interface allowing interconnection with a given service provider's network
Operating Expensescosts associated with sales and administrative functions, as distinct from those associated with production
Operating Revenuesincome earned from the provision of services and sale of goods during a given period
Optical Fibrethe medium and technology associated with the transmission of information as light pulses guided over a filament of transparent dielectric material, usually glass or plastic. An optical fibre usually has a cylindrical core surrounded by, and in intimate contact with, a cladding of similar geometry
Originating Calla call initiated by a subscriber
Originating Minuteone billed minute of conversation time on a call initiated by a subscriber
OSI reference modelOpen Systems Interconnect. A vertical, seven-layer model published by the ISO as a standard for data communication which has become a common reference point as to network protocols and services, ranging from the physical communications medium at the bottom to applications at the top. The CRTC's telecom monitoring process is based on a simplified, three-layer OSI model which retains the bottom-most layer one, calling it capacity; collapses layer two and layer three of the OSI model into connectivity; and collapse upper layers into applications


PAGING SYSTEMA one-way mobile radio service where a user carries a small, lightweight miniature radio receiver capable of responding to coded signals. These devices, called "pagers," emit an audible signal, vibrate or do both when activated by an incoming message.
PERSONAL COMMUNICATIONS SERVICE (PCS)Any of several types of wireless, voice and/or data communications systems, typically incorporating digital technology. PCS licenses are most often used to provide services similar to advanced cellular mobile or paging services. However, PCS can also be used to provide other wireless communications services, including services that allow people to place and receive communications while away from their home or office, as well as wireless communications to homes, office buildings and other fixed locations.
PRESCRIBED INTEREXCHANGE CHARGE (PICC)The charge the local exchange company assesses the long distance company when a consumer picks it as his or her long distance carrier.
PacketA unit of data formatted for transmission on a network. Data is broken up into packets for sending over a packet switching network. Each packet has a header containing its source and destination, a block of data content, and an error-checking code. All the data packets related to a message may not take the same route to get to their destination; they are reassembled once they have arrived
paginga service that allows transmitting a signal via radio from any telephone in the PSTN to a personal, portable receicing device in a defined operating area. More sophisticated systems provide audible or visual display messages
payphonea public telecommunications terminal which provides coin- or card-based billing on a per-transaction basis. Examples of payphone-provided services include PSTN telephony, PSTN data jack, PSTN fax, Internet Web, Internet e-mail, and SMS services; voice payphones, however, must provide direct-dial PSTN services, either via a voice handset or via a jack permitting data services to be dialled over PSTN lines. Payphones are located indoors, outdoors, or in transportation vehicles such as airplanes and trains, where each location type includes semi-public phones available on a restricted basis owing to their location, for example payphones on private premises such as restaurants
PBXPrivate Branch Exchange. A private voice-communications-capable switching facility located in an end-user organizaton's premises which provides on-premises connection between terminals connected to it, including dial service, and may provide connections to between those terminals and other communications networks, including the PSTN
PCSPersonal Communications Service. A broad service description for communications protocols using radio frequencies in the 1900 MHz frequency band to provide mobile telecom services, including interoperability with the wireline PSTN (public switched telephone network). Introduced in 1995 in Canada, PCS may be delivered using CDMA, TDMA, or GSM TDMA protocols. Outside Canada and the U.S., the PCS service description often refers to the 1800 MHz frequency band
peering settlement-free exchange of routing announcements between two Internet service providers for the purpose of ensuring that traffic from the first can reach customers of the second, and vice-versa
POP3Post Office Protocol, version three. See e-mail
postal codecodes used by postal services to divide large geographic areas into discrete zones in order to simplify delivery. In Canada, postal codes are six-character strings structured in the alphanumeric format Letter/Number/Letter; full space; Number/Letter/Number—for example, A1A 1A1. The first three characters of the postal code are known as the Forward Sortation Area (FSA), and represent a geographic area; the final three characters of the postal code are known as the Local Distribution Unit, and identify part or all of a street, an apartment building, or a group of rural post offices
postpaid serviceA service for which a significant portion of services and usage are paid in arrears, subsequent to consuming the services
prepaid serviceA service for which a significant portion of services and usage are paid in advance, prior to consuming the services. Prepaid service is especially prominent in mobile voice communications, where a subscriber prepays for a set amount of airtime in advance of actual usage
PSTNPublic Switched Telephone Network. The worldwide set of interconnected switched voice telephone networks that deliver fixed telephone services to the general public and are usually accessed by telephones, key telephone systems, private branch exchange trunks, and certain data arrangements, transmitting voice, other audio, video, and data signals. Completion of a PSTN circuit between the call originator and the call receiver requires network signalling in the form of either dial pulses or multifrequency tones. The PSTN includes local loops; short-haul trunks; long-haul trunks, including international links; exchanges; and switching technology
protocola set of formal rules and specifications describing how functional units should interact, especially within a network. For example, a data link protocol is the specification of methods whereby data communications over a data link are performed in terms of the particular transmission mode, control procedures, and recovery procedures
PABX - Private Automatic Branch ExchangeA private automatic telephone exchange, usually located at the user's site, that routes and interfaces the local business telephones and data circuits to and from the public telephone network
Packet SwitchingA communications data transmission method that breaks down messages into smaller units of standard sized pieces called packets, which are individually addressed and routed through a network; the network link is occupied only during packet transmission. Packet switching increases efficiency in transport
PALPhase Alternation by Line, the 625-line, 25-frame-per-second TV standard used in Western Europe, India, China, Australia, New Zealand, Argentina, and parts of Africa. Brazil uses PAL-M, a 525-line varian
Parabolic DishA satellite antenna, usually bowl-shaped, that concentrates signals to a single focal point
Pay-Per-View - PPVUsage-based fee structure used sometimes in cable television programming in which the user is charged a price for individual programs requested. Peripheral: Device such as a communications terminal that is external to the system processor
PCM - Pulse Code ModulationA method of converting analog sound into digital representation by use of successive samples
PDA - Personal Digital AssistantSmall, hand-held devices that combine computer power with graphics, sound, video and communication capabilities. They will take several forms including electronic note takers and portable display telephone. They hold various programs, address files and databases depending on the user's needs. Many feature a modem, fax, radio mail and computer
PhotonicsGallium arsenide integrated circuits for optical interconnections within and between computer and communication equipment called GaA. Present fiber optic computer and communication links are limited by discrete component electronics. In development is a projected 32-channel parallel monolithic IC connector which could vastly increase performance and drive down costs to open up long- sought new fiber optic markets which can replace current copper-wired connections
Picture ElementOne of many monochrome or color "dots" that comprise a television picture
Picture SignalThat portion of the composite video signal which lies above the blanking level and contains the picture brightness information
PingA program that can trace the route a message takes from your site to another site
PlatformRefers to different computer types or operating environments; e.g., Macintosh, DOS/Windows, CD-I and Sega are different platforms
Point of Presence - POPThe point where the inter-exchange carrier's responsibilities for the line begin and the local exchange carrier's responsibility ends. Location of a communications carrier's switching or terminal equipment
Point-to-MultipointA teleconference broadcast from one location to several receiving locations
Point-to-PointTeleconference between two locations. Point-to-Multipoint - one location to many sites
PolarizationA characteristic of the electric field on an electromagnetic wave in space. The directional aspects of a signal. Signals can have circular or planar polarization. Four types of polarization are used with satellites; horizontal, vertical, right-hand circular and left-hand circular. Electromagnetic waves have the ability to vibrate in different radial directions. Typically, satellite signal polarization is either horizontal or vertical. The signal coming from the satellite to the dish will either be vibrating along a horizontal or vertical plane. The receiving equipment must be adjusted to receive the correct polarization
PolycarbonateMaterial from which compact discs are made
POP - Post Office ProtocolA protocol for the storage and retrieval of e-mail. Eudora uses POP
PortIn software, the act of converting code so that a program runs on more than one type of computer. In networking, a number that identifies a specific "channel" used by network services. For instance, Gopher generally uses port 70 but is occasionally set to use other ports on various machines
Portable TransmitterA transmitter so constructed that it may be moved about conveniently from place to place but not ordinarily used while in motion, although some portable communications equipment does provide the capability to used while in motion
PostTo compose a message for a Usenet newsgroup and then send it out for others to see
Post-ProductionFor a program which is not a live broadcast, all the footage would be shot with the talent on a set constructed for the purpose or in remote locations. After the shooting, the post-production begins. The tape is electronically edited on video editing equipment. Music and graphics might be added. When the editing is finished, the program is complete. It then might be sold as a training video, situation comedy, drama, etc. Most commercial productions are produced this way, even though it might appear to be a live broadcast
PostmasterThe person to contact at a particular site to ask for information about the site or complain about one of his/her user's behavior
PostScriptA page-description language, developed by Adobe Systems, that converts any computer image - whether text or graphics - to a form that compatible output devices can interpret and print. PostScript typefaces can be printed on any PostScript compatible printer
POTSPlain Old Telephone Service
PPP - Point-to-Point ProtocolPPP provides a method for transmitting datagrams over serial point-to-point links
ppsPackets per second
Pre-ProductionThe first phase of a videoconference. Pre-production includes planning, research, script writing, developing taped segments to be dropped into a live production, hiring and rehearsing talent, and anything else done up to minute the broadcast begins
Pre-Produced SegmentsVideo segments done prior to the day of the broadcast/production. These are videotaped and edited segments which will be shown during the broadcast to take the audience into the field for interviews, demonstrations, or on site visits to places that somehow embody the content. For example, in a program about environmental pollution, a pre-produced segment might show a polluted stream with beer cans and dead fish. It might show the source of the pollution such as chemical or sewage processing plants
Printed Circuit (PC) BoardA circuit board whose electrical connections are made through conductive material that is contained on the board itself, rather than with individual wires
Printer FontThe software that contains the image of a typeface in outline form; used by a laser printer or imagesetter to produce the image on paper or film. Also called outline font
Programming LanguageAn artificial language, established for expressing computer programs, which uses a set of characters and rules whose meanings are assigned prior to use
Projection TelevisionA combination of lenses and/or mirrors that project an enlarged television picture on a screen
PROM - Programmable read-only memoryA type of read-only memory that can be programmed by the computer user. This programming usually requires special equipment
Prompt1. Any symbol or message presented to an operator by an operating system, indicating a condition of readiness, location, or that particular information is needed before a program can proceed. 2. When the host system asks you to do something and waits for you to respond. For example, if you see "login:" it means type your user name
PRO-Que ChannelPRO is a term used primarily in television transmissions to designate a separate audio voice grade signal sent with a television channel which is used for program instructions and queuing for the broadcast engineers. The voice quality 3 kHz channel may contain audio or data as may most be appropriate for the specific application. It is not received by a standard television receiver without special equipment
Power userA computer user who is quite skilled in the use of computers over a variety of applications
Public Access ProviderAn organization that provides Internet access for individuals or other organizations, often for a fee
Public Switched NetworkAny switching system that provides a circuit switched to many customers
Pulse Code ModulationA time division modulation technique in which analog signals are sampled and quantized at periodic intervals. The values observed are typically represented by a coded arrangement of 8 bits of which one may be for parity
PTT - Post, Telephone & Telegraph AdministrationRefers to operating agencies directly or indirectly controlled by government in charge of telecommunications services in most countries of the world


QuickTimeApple's multimedia extension to its System 7 operating software for the Macintosh. It is a time-based management system for combining text, graphics, sound, still images, animations and video. The software incorporates its own compression technology so that digitized movies can be stored and played off of a computer hard disk


ROAMINGThe use of a wireless phone outside of the "home" service area defined by a service provider. Higher per-minute rates are usually charged for calls made or received while roaming. Long distance rates and a daily access fee may also apply.
Regionin Canada, six groupings of one or more geographically contiguous provinces and/or territories, as follows: Northern Territories (Yukon, Northwest Territories, Nunavut); British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; and Atlantic (Newfoundland and Labrador; New Brunswick; Nova Scotia; Prince Edward Island)
Related CompaniesRelated companies are determined in accordance with Section 3840 of the Handbook of the Canadian Institute of Chartered Accountants. Companies making monthly or annual filings on behalf of a group of related companies are required to file separate reports with supporting information for each company that is a telecommunications service provider. When filing your annual reporting form, a list of all related companies is required, whether or not the companies file separately or as part of a group. The minimum threshold of $10 million in Canadian Telecommunications Service Revenues applies to the group of related companies
Reporting EntityA legal entity which earned revenues in 2003 for any of the services listed in the Reporting Entity Profile form
Resalehe subsequent sale or lease on a commercial basis, with or without adding value, of a distinct telecommunications service or distinct telecommunications facilities provided by a supplier on a wholesale basis. Under sustainably competitive market conditions, the reseller attempts to price its services or facilities high enough to recover its wholesale cost, but low enough to remain competitive with facilities-based service providers in the same market. A distinct telecommunications service or facility is bounded horizontally by OSI network layers and vertically by market segments: value added beyond these boundaries is defined as creating a new service, not reselling an existing service or facility. Where a service provider leases a clear-channel trunk and provides its own ATM and IP routers to sell Internet transit on that trunk, for example, no resale may be said to have occurred, since the leasing of raw material (clear-channel trunk) occurs at a different network layer than the ATM (data link) or IP (network) services, and since the clear-channel private line is not itself resold to another entity. A company which provides a service on a resale basis is a reseller of that service, but the same company may also be a facilities-based provider or wholesaler of other services: a company may therefore be described as a reseller only with regard to a given service
Residential Accountan account billed to a private individual or household; sometimes referred to as a consumer account
Retailprovision of a telecommunications service or facility for end use, including trunking and backbone use. See also wholesale
Revenuethe inflow of cash or other assets received in exchange for providing goods or services to customers
Routera computer or other functional unit used as an interface between two or more network segments at layer three of the OSI reference model, routing traffic through these segments in such a way as to promote its arrival at the final destination to which it was addressed. An Internet router accomplishes this by reading the network layer address of each packet transmitted to it, making an algorithm-based decision about the next network segment hop which must be taken by each packet, and treating the packet accordingly
Rain Attenuation - Rain LossesThe attenuation (loss) of a signal due to rainfall. If you are receiving a teleconference on a Ku band dish, local rainstorms can drastically weaken the signal strength of the program. The result will be sparkles which interfere with the ability to see the program. During a heavy downpour or thunderstorm, signal reception may be lost temporarily. The noise temperature perceived by the receiving antenna may increase due to rain being present in the link
RAMRandom-access memory. A volatile memory used by a computer's central processing unit as a chalkboard for writing and reading information. RAM is measured in multiples of 4096 bytes (4K bytes), and serves as a rough measurement of a computer's capacity
RasterThe scanned (illuminated) area of a television picture tube
RBOCRegional Bell operating company
README filesFiles found on FTP sites that explain what is in a given FTP directory or which provide other useful information (such as how to use FTP)
Real Soon NowA vague term used on the Net to describe when something will actually happen
ReceiversConvert satellite signals into channels viewed (one at a time) on a TV monitor; designed to tune-in the format, bandwidth, and audio sub-carrier. Programs broadcast in code (encryption) are decoded at receive sites
Receive SiteThe site receiving the transmission from the origination site. A video teleconference might have 100 or more receive sites
Red BookThe specification for Compact Disc-Digital Audio
RedundantA backup satellite receive system which would go into operation if the primary system failed. Although the reliability of all electronics has greatly improved, it is desirable to have backup equipment in the receive chain; i.e., a duplicate of each item except the dish. Dual LNA's or BDCs can be mounted on dual feedhorns and could easily be switched in the event of primary system failure. Likewise, two receivers could be operated simultaneously using signal splitters, and either could be switched to the viewing room
ReflectorAntenna's main curved "dish," which collects and focus signals onto the secondary reflector or the feed
RepeaterA term used to describe the process of reprocessing and send a weak signal on to a more distant service area. The weak signal condition develops as the initially strong signal passes through the miles of air, moisture, rain and snow which gradually attenuates or reduces its power level
ResolutionA measure of picture resolving capabilities of a television system determined primarily by bandwidth, scan rates and aspect ratio. Relates to fineness of details perceived
RetraceThe return of a scanning beam to a desired position
RetrofittingThe installation of additional - equipment or the rebuilding of sections of a system after it has been installed
RF - Radio FrequencyRadio frequencies are generally considered as any electromagnetic signal from normal radio to microwave transmission
RFC - Request for CommentsThe Internet's Request for Comments documents series. The RFCs are working notes of the Internet research and development community. A document in this series may be on essentially any topic related to computer communication, and may be anything from a meeting report to the specification of a standard
RFD - Request for DiscussionThe part of the newsgroup creation process where you propose a group and discussion starts
RFIRadio frequency interference
RFPRequest for proposal
RGB - Red, Green BlueMethod of transmitting video signals that feeds red, green, and blue channels over separate wires; provides highest-quality video signal and is the format for most computer equipment
Ring NetworkA local area network in which devices are connected in a closed loop or ring as opposed to a bus network
ROMRead only memory. A type of permanent, non-erasable memory that plugs directly into the wiring of a computer, and contains computer programs. Some computers are supplied with some built-in ROM, whereas others have external slots for inserting ROM cartridges
ROTFL - Rolling on the Floor LaughingHow to respond to a particularly funny comment on the Net
ROT13A simple way to encode bad jokes or movie reviews that give away the ending, etc. Essentially, each letter in a message is replaced by the letter 13 spaces away from it in the alphabet. There are on-line decoders to read these; nn and rn have them built in
RoutingSelecting the minimum delay path (and/or minimum cost path) in a network for a message or packet to reach its destination
RS-232-CStandard interface between a piece of equipment and a telephone circuit
RS-250BThe technical standards established for the determination of a true broadcast quality signal. All technical parameters for each type of measurable signal degradation are at a level approximately ten times that first detectable as visible in a television picture by the average viewed
RTM - Read the manualOften used in flames against people who ask computerrelated questions that could be easily answered with a few minutes with a manual. Often RTFM


SATELLITEA radio relay station that orbits the earth. A complete satellite communications system also includes earth stations that communicate with each other via the satellite. The satellite receives a signal transmitted by an originating earth station and retransmits that signal to the destination earth station(s). Satellites are used to transmit telephone, television and data signals originated by common carriers, broadcasters and distributors of cable TV program material.
SATELLITE HOME VIEWER IMPROVEMENT ACT OF 1999 (SHVIA)An Act modifying the Satellite Home Viewer Act of 1988, SHVIA permits satellite companies to provide local broadcast TV signals to all subscribers who reside in the local TV station’s market. SHVIA also permits satellite companies to provide "distant" network broadcast stations to eligible satellite subscribers.
SATELLITE MASTER ANTENNA TELEVISION (SMATV)A satellite dish system used to deliver signals to multiple dwelling units (e.g., apartment buildings and trailer parks).
SCANNERA radio receiver that moves across a wide range of radio frequencies and allows audiences to listen to any of the frequencies.
SERVICE PLANThe rate plan you select when choosing a wireless phone service. A service plan typically consists of a monthly base rate for access to the system and a fixed amount of minutes per month.
SERVICE PROVIDERA telecommunications provider that owns circuit switching equipment.
SLAMMINGThe term used to describe what occurs when a customer’s long distance service is switched from one long distance company to another without the customer’s permission. Such unauthorized switching violates FCC rules.
SPECTRUMThe range of electromagnetic radio frequencies used in the transmission of sound, data and television.
SUBSCRIBER LINE CHARGE (SLC)A monthly fee paid by telephone subscribers that is used to compensate the local telephone company for part of the cost of installation and maintenance of the telephone wire, poles and other facilities that link your home to the telephone network. These wires, poles and other facilities are referred to as the "local loop." The SLC is one component of access charges.
S/N - S/NR - Signal to Noise RatioFinal relationship between the video or audio signal level to the noise level. Ratio of the signal power to the noise power in a specified band width, expressed in dBW
Sampling Rate/FrequencyThe number of samples taken per second of an analog signal, expressed in Hertz. A 44.1KHz sampling rate, used for CD-Audio sound, represents 44,100 samples per second
SAP - Supplementary Audio ProgramSAP is used to designate that part of the audio signal transmitted with the standard multi-channel sound television broadcast. The multi-channel audio signal contains stereo (left and right), SAP and PRO. The SAP signal is most often used in television broadcast applications for a second language
SCA - Subsidiary Communication AuthorizationRadio version of vertical blanking intervals (BVI). Public institutions that have access to FM have access to SCA. This electronic technique places the radio signal on the FM spectrum; these signals can only be picked up with special tuners that distinguish the SCA from the FM signals
SatelliteAn electronics retransmission device serving as repeater normally placed in orbit around the earth in the geostationary orbit for the purpose of receiving and retransmitting electromagnetic signals. It normally receives signals from a single source and retransmits them over a wide geographic area. Satellite C/Ku band Domestic communications satellites operate on two frequency ranges designated C and Ku band. Each require specific electronic equipment. C band is less expensive; operates at 4 kHz. Ku-band operates at 12 kHz. Some teleconferences are broadcast on both bands. Many satellites are now built with both C and Ku band capacity
Satellite Earth TerminalThat portion of a satellite link which receives, processes and transmits communications between Earth and a satellite
Satellite FootprintIn geostationary orbit, communications satellites have direct line-ofsight to almost half the earth - a large "footprint" which is a major advantage. A signal sent via satellite can be transmitted simultaneously to every U.S. city. Multiple downlinks can be aimed at one satellite and receive the same program; called point to multipoint
Satellite Master Antenna Television System - SMATVA system wherein one central antenna is used to receive signals (broadcast or satellite) and deliver them to a concentrated grouping of television sets (such as might be found in apartments, hotels, hospitals, etc.)
Satellite ReceiverA microwave receiver capable of receiving satellite transmitted signals, downconverting, and demodulating those signals, and providing a baseband output (e.g., video and audio). Modern receivers are frequency agile and usually capable of multiple band reception (e.g., C band and Ku band.)
Satellite RelayAn active or passive satellite repeater that relays signals between two earth stations
Satellite SystemThe use of orbiting satellites to relay transmissions from one satellite dish to another or multiple dishes
ScalabilityThe ability to vary the information content of a program by changing the amount of data that is stored, transmitted or displayed. In a video image, this translates into creating larger or smaller windows of video on screens
Scan-ConverterA device that converts video frequency signals to audio frequencies and vice versa; used in freeze-frame video to transmit video signals over telephone lines
ScannerA device for digitizing text, drawings or photographs - anything in paper form. It works like a photocopy machine, but instead of paper, the scanner converts the printed information into digital images. Scanners are used with OCR (optical character recognition) technology, which takes the scanned pages of text and graphs and converts them into the individual letters and words that make up the text and the dots that make up the image, so that the text and images can be edited using a computer
ScanningThe process of breaking down an image into a series of elements or groups of elements representing light values and transmitting this information in time sequence
SCPC - Single Channel Per CarrierSignal transmission technique often used in satellite transmission which concentrates one channel of information on a single transmitted carrier for relay through the satellite. The channel may be digital, analog or multiplexed analog in nature provided that its information may be sent on a single narrow band carrier. The Single Channel Per Carrier transmission technique allows multi-channel operation in the satellite with access from any location on the earth
SCPTSingle carrier per transponder
ScrambleTo interfere with an electronic signal or to rearrange its various component parts. In pay television, for example, the signal might be scrambled, and a decoder, also called a descrambler, might be necessary for the signal to be unscrambled so that only authorized subscribers would receive the clear signal
ScramblerA device that transposes or inverts signals or otherwise encodes a message at the transmitter to make it unintelligible to a receiver not equipped with an appropriate descrambling device. Synonymous with encoder
Screen CaptureA part of communications software that opens a file on the computer and saves to it whatever scrolls past on the screen while connected to a host system
SCSI - Small Computer System InterfacePronounced "scuzzy." A standard interface used to connect peripheral devices, such as a CD-ROM drive, to a computer
Screen DensityThe maximum number of accessible screen elements in a video display
ScrollingA property of most alphanumeric video display terminals. If the screen of such a video terminal is filled, it will move the entire display image upward, either at a smooth pace or one line at a time, so that room is continuously made at the bottom of the screen for new information
seaSelf-extracting Archive: A compressed file or files encapsulated in a decompression program; needs no other program to expand the archive
SEA - State Educational AgencyThe state board of education or other agency officer primarily responsible for the supervision of public elementary and secondary schools in a state. In the absence of this officer or agency, it is an officer or agency designated by the governor or state law
Search EngineA program which finds and presents data. Same as retrieval engine
SECAMSysteme Electronique pour Couleur Avec Memoire, the 625-line, 25-frameper-second color television -system used in France, Eastern Europe, USSR and parts of Africa
SectorA physical data block of a CD-ROM
SeekIn CD-ROM drives, the act of locating requested data on a disc. Seek Time: Usually expressed in terms of "average seek time," it provides a comparative number indicating the time required to get from one position to another, in reading a CD-ROM. Some older CD-ROM drives had seek times in excess of 1,000 milliseconds (ms), or one full second. The newest drives have seek times approaching 200ms
Selective Addressability - Selectively Addressable ScramblingThe capacity to designate selected receivers to descramble a particular signal. Each decoder has a unique "address." First developed as the pay-per-view option for cable TV, then adopted by satellite networks
ServerA computer that can distribute information or files automatically in response to specifically worded e-mail requests
ServoIn CD-ROM drives, an electro-mechanical device that uses feedback to achieve precise starts and stops for movements of the optical head and focusing of the laser beam
SemiconductorA material whose resistivity lies between that of conductors and insulators, e.g., germanium and silicon. Solid state devices such as transistors, diodes, photocells, and integrated circuits are manufactured from semiconductor materials
Semiconductor MemoryComputer memory using solid state devices instead of mechanical, magnetic, or optical devices
Serial Input/OutputData transmission in which the bits are sent one by one over a single wire
SharewareSoftware that is freely available on the Internet. If you like and use the software, you should send in the fee requested by the author, whose name and address will be found in a file distributed with the software
Shared Visual SpaceAllows participants to interact with a common graphics display area; e.g., any person can make a change which is seen by all
.sig fileSometimes, .signature file. A file that, when placed in your home directory on your public-access site, will automatically be appended to every Usenet posting you write
.sig quoteA profound/witty/quizzical/whatever quote that you include in your .sig file
Sign-On ProcedureThe process of connecting with a remote computer, including the provision of identification details and security access
Signal-to-NoiseThe amount of useful information to be found in a given ratio
Silicon ChipA wafer of silicon providing a semiconductor base for a number of electrical circuits
SIMM - Single In-line Memory ModuleDevices used to add memory to computers
SimplexA circuit capable of transmission in one direction only. Contrast with half duplex and full duplex
SIMTEL20The White Sands Missile Range used to maintain a giant collection of free and low-cost software of all kinds, which was "mirrored" to numerous other ftp sites on the Net. In the fall of 1993, the Air Force decided it had better things to do than maintain a free software library and shut it down. But you'll still see references to the collection, known as SIMTEL20, around the Net
SimulationSimulation programs electronically substitute media for the actual experience, but may be coupled with hands-on devices that help the learner to experience physical movement
Single SessionA drive that can read discs on which data was recorded only once, or a CD-ROM on which data was recorded in one pass, either through CD-Recordable technology, or the standard mastering process
SiteThe origination site is the location from which video and/or audio is transmitted and uplinked in a teleconference. Receive transmission from the origination site
SkewThe angular deviation of recorded binary characters from a line perpendicular to the reference edge of a data medium
SkewingHorizontal displacement of video information in bands of approximately 16 lines per field producing a sawtooth effect which is most apparent on vertical picture detail of a television picture originating from the playback of a video tape recording
SLIP - Serial Line Internet ProtocolSLIP is currently a de facto standard, commonly used for point-to-point serial connections running TCP/IP. It is not an Internet standard but is defined in RFC 1055
Slow ScanUses transmitters that scan selected frames and transmit the visual information over telephone lines to receive sites where it is reconstituted as a still picture. May refer to still frame video that accepts an image from a camera or other video source one line at a time
SMATVSatellite master antenna television. A distribution system that feeds satellite signals to a hotel, motel, apartment complex, etc
SMDS - Switched Multimegabit Data ServiceA public network service that will enable customers to send packets between LANs at either T-1 or T-3 rates. Switched Multimegabit Data Service is offered by public network providers and is a connectionless (i.e., datagram) service. It will enable customers to exchange packets between sites at T1, T3 at potentially higher rates. This LAN-like service will be offered by local exchange carriers and will initially be available only within selected metropolitan areas. A typical SMDA customer will have a wide-area communications device - i.e., a router - connected to a campus LAN or backbone, which interface through a subscriber line to the local telco central office. The communication between the customer premises device (e.g., the router) and the telco will adhere to a protocol called Subscriber Interface Protocol (SIP). This protocol has three levels, only two of which are standardized Levels 1 and 2 are fashioned from the IEEE 802.6 MAC standard for metropolitan area networking, which is called the Distributed Queued Dual Bus (DQDB) protocol. The third layer was promulgated by Bellcore in one of its Technical Advisories. The SMDS service will support both T1 and T3 access from the user's router to the local exchange carrier's central office. SMDS is considered by the regional Bell operating companies (RBOCs) to be their first broadband service, and it will eventually be incorporate as a service offering for Broadband ISDN (BISDN) family of services in the late 1990s
SMTP - Simple Mail Transfer ProtocolThe Internet standard protocol for transferring electronic mail messages from one computer to another. SMTP specifies how two mail systems interact and the format of control messages they exchange to transfer mail
SNASystem network architecture
Snail MailMail that comes through a slot in your front door or a box mounted outside your house
SNMPSimple Network Management Protocol The Internet's standard for remote monitoring and management of hosts, routers and other nodes and devices on a network (RFC 1157)
Snow/Ice on the Satellite DishA significant build up of snow (4-5 inches) on the dish can interfere with signal reception. Snow can be removed with a soft broom or soft cloth. Since accurate curvature of the dish is vital to a good signal, avoid banging or hitting the dish. Ladders should not be leaned against the dish as it may warp or change the azimuth and/or elevation setting. A small amount of ice should not cause problems
SoftwareA set of programs, procedures or related documentation associated with a system; materials for use with audio visual equipment; programs in contrast to equipment
Solar OutageIf an antenna is pointed at or near the sun, the sun's high radiated noise level may be many times stronger than the desired signal
Solid StateA class of electronic components utilizing the electronic or magnetic properties of semiconductors
SONET - Synchronous Optical NetworkWill offer dedicated point-to-point lines via fiber, with bandwidths ranging from 51.84 mbps to over 2gbps. SONET defines optical interfaces for high speed digital transmission - ranging from 51.84 mbps to more than 2 gbps in multiples of 51.84 mbps. The purpose of the SONET standard is to guarantee that fiber, and fiber terminating equipment (e.g. digital loop carrier systems) from different central office vendors, can all interface with each other. While many trials are currently under way to test the SONET central office standards, all new fiber deployment is expected to be compliant with this standard
Sound boardA device required by a DOS-based computer to access digital sound, exists in the form of an add-in board inserted in the computer, and accesses (and/or creates) .WAV, .SND, MIDI and other digital sound formats
Special Event TeleconferencingTeleconference that uses facilities that are temporarily linked for a specific event; implies a temporary satellite network for one-way video and two-way audio
Specialized Common Carrier1. A company authorized by a government agency to provide a limited range of telecommunications services. Examples of specialized common carriers are the value- added networks. fi2. Those common carriers not covered in the original federal communications legislation
SpectrumRange of electromagnetic radio frequencies used in transmission of voice, data, and TV
Spin UpCome up to speed. When a CD-ROM is inserted in a drive, it must reach a certain rate of rotational speed in order to be read
SS7 - Signaling System 7Increases both the efficiency of the telcos' interoffice trunking facilities and their opportunities for revenue generation by enabling networkwide services. With SS7 trunk signaling, premium services such as ISDN and Custom Local Area Signaling Service can be easily and efficiently extended across the network
SSMA - Spread Spectrum Multiple AccessFrequency modulation technique. Standard Broadcast Band: The band of frequencies extending from 535 to 1605 kHz, usually called AM
Star NetworkA network configuration in which there is only one path between a central or controlling node and each end-point node
StationAssigned satellite location
StereophonicGiving, relating to, or constituting a three-dimensional effect of auditory perspective, by means of two or more separate signal paths
Still-Image VideoSystem by which still images are transmitted over standard telephone lines, usually allowing for real-time interaction between locations
STL - Studio Transmitter LinkDescription of a type of microwave link which connects a television studio to the television station transmitter location. The designation is used Telecommunications Glossary/81 by the Federal Communications Commission to differentiate a specific band of frequencies allocated for this specific application
StudioA specially designed room with associated control and monitoring facilities used by a broadcaster for the origination of radio or television programs
SubcarrierSignal which is transmitted along with the main video signal carrier. Subcarriers can transmit data, color picture information or audio
Subscription Television - STVThe broadcast version of pay television. Not a cable service, it is distributed as an over-the-air broadcast signal. Its signals are scrambled and can be decoded only by a special device attached to the television set for a fee. STV contains no commercials
SuperbandThe band of cable television channels J through W lying between 216 and 300 MHz
SupercomputersThe fastest and most powerful computing systems that are available at any given time
Surfing the InternetSkimming across topics on the Internet - moving in and out of systems looking for information that is not specified. More like browsing than a true search. Also net surfing
SwitchMechanical or solid-state device that opens or closes circuits, changes operating parameters or selects paths for circuits on a space or time division basis
Switched CircuitA circuit that may be temporarily established at the request of one or more stations
Switched NetworkAny network in which switching is present and is used to direct messages from the sender to the ultimate recipient. Usually switching is accomplished by disconnecting and reconnecting lines in different configurations in order to set up a continuous pathway between the sender and the recipient
Switched SystemA communications system (such as a telephone system) in which arbitrary pairs or sets of terminals can be connected together by means of switched communications lines
Symmetrical CompressionA compression system that requires equal processing capability for compression and decompression of an image. Used in applications where both compression and decompression will be utilized frequently. Examples include stillimage databasing, still-image transmission (color fax), video production, video mail, videophones and videoconferencing. Asymmetrical Compression requires more processing capability to compress an image than to decompress an image. It is typically used for the mass distribution of programs on media such as CD-ROM
Synchronous CommunicationCommunication which takes place in the same time frame. Examples are live teleconferences which must be viewed when they are Telecommunications Glossary/82 broadcast. If the teleconference is taped and viewed later, it becomes asynchronous communication - communication which takes place at the convenience of the end user through the technology of video tape recording
Synchronous TransmissionData characters and bits are transmitted at a fixed rate with the transmitter and receiver synchronized. This eliminates the need for start-stop elements, thus providing greater efficiency
Syntax ErrorA mistake in the formulation of an instruction to a computer
SysadminThe system administrator; the person who runs a host system or publicaccess site
Sysop - A System OperatorSomebody who runs a bulletin board system or network; responsible for keeping the network or BBS working properly
Service Addressthe most precise civic address of the site at which a given telecommunications facility terminates or at which telecommunications service is delivered by the service provider, regardless of the point of billing. See also billing address.
Service Chargea one-time charge billed to an end user for installation, addition, or removal of lines, equipment, services, premise wiring, repairs, or maintenance services, whether on or off the customer's premises.
Service Providerany private person or legal entity who provides any telecommunications service to any other private person or legal entity for compensation
Settlement Rateusually, one-half of the per-minute accounting rate determined under the auspices of the ITU to establish the theoretical full cost of an international PSTN communication on a given country-to-country route. The settlement rate is the amount paid by the originating service provider to the terminating service provider to reimburse the theoretical half-circuit cost. With private intercarrier arrangements and FCC benchmark rates, the accounting rate system is today one of three major systems used to determine PSTN international interconnection payments
Short-Haul Backbonea metropolitan area core network made up of point-to-point intracity network segments whose function is to transit network traffic between edge nodes
Small Businesswithin the context of commercial users of telecommunications services, a small business is any commercial entity whose telecommunications service fees generate revenues of less than $500 per month or $6,000 per year. Medium-size businesses are commercial entities whose telecommunications service revenues generate more than $500 per month, but less than $2,500 per month. Large businesses are commercial entities that generate a minimum of $2,500 per month in revenues
SMSShort Messaging Service. A wireless messaging service that permits the transmission of a short text message from and/or to a digital mobile telephone (CDMA, including CDMA 1xRTT and other CDMA-based implementations; TDMA; GSM; or ESMR) terminal, regardless of whether the transmission originates and terminates on a mobile telephone, originates on a mobile telephone and terminates on a computer, or originates on a computer and terminates on a telephone
SONET(Synchronous optical network) An interface standard for synchronous optical-fibre transmission, applicable to the physical layer of OSI Reference Model
Switching and Aggregationa tariffed interconnection charge which a service provider must pay another service provider to load PSTN traffic off the former's and onto the latter's network. Switching and aggregation may be paid to terminate traffic onto a local access line (local switch) or to transport traffic across a toll network (toll tandem)


TARIFFThe documents filed by a carrier describing their services and the payments to be charged for such services.
TELECOMMUNICATIONS RELAY SERVICE (TRS)A free service that enables persons with TTYs, individuals who use sign language and people who have speech disabilities to use telephone services by having a third party transmit and translate the call.
TELEPHONYThe word used to describe the science of transmitting voice over a telecommunications network.
TTYA type of machine that allows people with hearing or speech disabilities to communicate over the phone using a keyboard and a viewing screen. It is sometimes called a TDD.
T1 (DS-1) ChannelHigh-speed digital data channel/carrier with a bit rate of 1.544 mbps which requires a bandwidth of approximately 2.1616 MHz to transmit in a television type cable environment. (1.4 x 1.544 = 2.1616); a general term for a digital carrier (DS-1. available for high-volume voice or data traffic; often used for compressed video teleconferencing networks. Each T1 circuit can accommodate 24 voice channels. A video codec operating at the T1 rate uses the equivalent of 24 voice channels. A codec operating at 56 or 64 Kbps is operating in the range of one voice channel. A standard video signal digitized at 90 Mbps has approximately 1400 voice channels. The compressed video signal quality and the cost decreases as the transmission speed decreases
T.129 Series StandardsThe T.120 standard contains a series of communication and application protocols and services that provide support for real-time, multipoint data communications. These multipoint facilities are important building blocks for a range of collaborative applications, including desktop data conferencing, multi-user applications, and multi-player gaming. Through it data is seamlessly delivered to multiple parties in "realtime." It allows endpoint applications from multiple vendors to interoperate. It specifies how applications may interoperate with (or through) a variety of network bridging products and services that support the T.120 standard. It is completely free from any platform dependencies including OS/2, MAC/OS, several versions of UNIX, and other proprietary real-time operating systems. The T.120 standard supports a broad range of transport options, including the Public Switched Telephone Networks (PSTN or POTS), Integrated Switched Digital Networks (ISDN), Packet Switched Digital Networks (PSDN), Circuit Switched Digital Networks (CSDN), and popular local area network protocols (such as TCP/IP and IPX via reference protocol). These network transports operate at different speeds, but can easily co-exist in the same multipoint conference. T.120 was designed to work alone or with in the larger context of other ITU standards such as the H.321x family of video conferencing standards and V.series modems
T3 (DS-3A carrier of 45 mbps bandwidth; one T3 channel can carry 28 T1 channels. Used for point-to-point digital video transmissions or for major PBX-PBX interconnection. Dedicated service delivered via fiber. The price for a T3 circuit can be comparable to seven to 12 T1 circuits. In addition to being offered by the traditional local and interexchange carriers, a number of alternative access carriers offer T3 circuits in major metropolitan areas
Talk-back CircuitAn audio return link from a receive location to the originating video/audio point. The equipment used is generally either a leased telephone line, dedicated radio link, or special microwave equipment made for this service
TANSTAAFLInternet shorthand for "There Ain't No Such Thing as a Free Lunch."
.tarThe filename extension used by files made into an archive by the Unix tar program
TBC - Time Base CorrectorAn electronic accessory to a videotape recorder that helps make mixed format playback or transfers electronically stable. It helps maintain picture quality even in dubbing operations within a single tape format
TCPTransmission Control Protocol
TCP/IP - Transmission Control Protocol/Internet ProtocolThe combination of TCP and IP. The particular system for transferring information over a computer network that is at the heart of the Internet.: IP is the network layer protocol for the Internet. It is a packet switching, datagram protocol defined in RFC 791
TDMA - Time Division Multiple AccessForm of multiple access where a single carrier is time shared by many users. Signals from earth stations reaching the satellite consecutively are processed in time segments without overlapping
TelcoGeneric name for telephone companies
TelecommunicationsCommunicating over a distance. Use of wire, radio, optical or other electromagnetic channels to transmit or receive signals for voice, video and data communications
Telecommuter - telecommutingAbility to work from home, local office, or from the road because of equipment. Equipment allows the telecommuting employee to work from anywhere. The equipment includes a telephone, fax, modem and as the NII is deployed, video
TelecomputerEquipment used to receive digitized information in audio, video, and data modes
TeleconferenceElectronic communications between two or more groups, or three or more individuals, who are in separate locations via audio, audiographics, video or computer. Audio teleconference - two-way communication between two or more groups, or three or more individuals, in separate locations. Video teleconference - one (or more) uplink and downlink sites. May be fully interactive voice and video, two-way voice and one-way video; full-motion, compressed, or freeze-frame video
TelemetryThe science of sensing and measuring information at some remote location and transmitting the data to a convenient location to be read and recorded
TelenetA public packet-switching network operated by US Sprint. Also known as "SprintNet"
TelnetThe Internet standard protocol for remote terminal connection service. Allows a user at one site to interact with a remote time sharing system at another site as if the user's terminal was connected directly to the remote computer (see "rlogin"). On the Macintosh, NCSA Telnet is the standard
Telephonythe use or operation of an apparatus for transmission of sounds between widely removed points with or without connecting wires
TeleportA generic term referring to a facility capable of transmitting and receiving satellite signals for other users
TeletextBroadcast service using several otherwise unused scanning lines (vertical blanking intervals) between frames of TV pictures to transmit information from a central data base to receiving television sets. Users of a teletext service grab pages from the transmission cycle using a keypad similar to that used in videotex systems
TelevisionThe electronic transmission of pictures and sounds
TelewriterGeneral term for an electronic device that produces free-hand information that can be sent over a telecommunications channel, usually a telephone line
Terminal1. Generally, connection point of equipment, power or signal. 2. Any terminating piece of equipment such as a computer terminal
TextIn terms of files, a file that contains only characters from the ASCII character set. In terms of FTP, a mode that assumes that files will be transferred containing only ASCII characters
Terrestrial Carrier/Land LineTelecommunications transmission system using landbased facilities (microwave towers, telephone lines, fiber optic cable)
Thicknet - ThinnetThicknet cable can support longer distances than Thinnet (500 meters) and have up to 100 nodes connected to it. Thinnet cable looks similar to television cable and is often used to connect networks within limited distances (185 meters) and limited nodes (35)
TI - Terrestrial InterferenceTI is normally generated as a result of relatively strong terrestrial microwave signals overpowering the weak satellite transmissions which are the primary signals of interest at a satellite earth station
ThreadA group of messages in a Usenet discussion group that all share the same subject and topic, so one can easily read the entire thread or delete it, depending on the specific newsreader
Time Code:Code electronically placed on a videotape that appears on the screen or on a counter to locate specific footage and edit tape. Logs are made of the footage on tape before editing so it can be located and viewed quickly during the editing
Time SharingPertaining to the interleaved use of time on a computer system that enables two or more users to execute computer programs concurrently
Token RingA type of LAN. Examples are IEEE 802.5, ProNET-10/80 and FDDI. The term "token ring" is often used to denote 802.5
Touch ScreenA video-and/or computer monitor which responds to the user's finger touch in order to control the program
TransceiverTerminal that transmits and receives
Transfer RateThe amount of data that can be communicated from the CD-ROM drive to the CPU. Standard CD-ROM data transfer rate is 155KB/sec, (often rounded to 150KB/sec)
Transmission ChannelThe medium by which a signal is sent and received between separate locations
Transponder - Channel - Downlink FrequencyA satellite microwave repeater (receiver and transmitter) receives the signal from an uplink, amplifies it, down converts the frequency of a received band of signals, and re-transmits the signal back to earth. Satellites have 12, 24, or more transponders each with the capacity for one color TV signal and two audio channels. Typically transponder with 24 transponders have twelve polarized for vertical and twelve for horizontal transmissions in order to optimize the bandwidth of the satellite and the respective transponders
TreatmentA narrative description of a media program. In videoteleconferencing, usually describes routine of action and precedes a rundown and/or script
TunerA device, circuit, or portion of a circuit that is used to select one signal from a number of signals in a given frequency range
TVRO - Television Receive OnlyEarth stations which receive (but not transmit) satellite transmissions. Normally comprised of a parabolic antenna, low noise converted (LNC) or low noise amplifier (LNA) and a satellite receiver. The antenna gathers the weak signals transmitted from the communications satellite located in the geostationary orbit which are then amplified and downconverted to a more usable portion of the spectrum by the low noise converted. From the LNC the signals may travel up to several hundred feet to a satellite receiver; the output of which is typically video and audio or modulated channel three or four. 23B+D The capability of ISDN primary rate interface (PRI) to enable data terminals served by a DMS-100 ISDN node to have fully digital circuit- and packet-switched ISDN internetworking with data terminals served by PBXs
Twisted PairA pair of wires used in transmission circuits and twisted about one another to minimize coupling with other circuits. UTP - unshielded twisted pair
Two-way Interactive TelevisionTwo-way interactive television provides real-time, two-way visual contact and audio contact between students in two or more classrooms and their instructor/facilitator who may be at one of the sites or a separate origination site. Two-way compressed video systems are not all delivered at the same speed. Some are full-motion video and some are delivered at slower speed so that the picture and audio are delayed in delivery and do not have the same appearance as full NTSC video. Some systems use full fiber optic or T1 lines for delivery while other use a partial T1 or ISDN for delivery of the signal. Signals are also delivered compressed to a part of Telecommunications Glossary/87 a satellite transponder. The reason for using partial lines and partial transponders is to use less bandwidth. Less bandwidth for the transmission reduces the cost to deliver the signal
Two-Wire CircuitA typical telephone circuit on the public switched network; a circuit formed by two conductors insulated from each other to provide a send and receive channel in the same frequency


UNBUNDLINGThe term used to describe the access provided by local exchange carriers so that other service providers can buy or lease portions of its network elements, such as interconnection loops, to serve subscribers.
UNIVERSAL SERVICEThe financial mechanism which helps compensate telephone companies or other communications entities for providing access to telecommunications services at reasonable and affordable rates throughout the country, including rural, insular and high costs areas, and to public institutions. Companies, not consumers, are required by law to contribute to this fund. The law does not prohibit companies from passing this charge on to customers.
UHF-VHFUHF stands for ultra high frequency television transmission channels above channel 13 (Channels 14-3.. VHF stands for very high frequency; television transmission channels 2 through 13
UnionsThe unions most closely associated with video production. Usually, if one group of people on a production are union, all will be. They may belong to the following unions: Actors Equity represents actors in certain areas of the country . AFM : American Federation of Musicians. This union represents professional musicians in all areas of performance - recording and personal appearance. AFTRA : American Federation of Television and Radio Artists. A union for artists who perform on broadcast media, including tape. BMI and ASCAP : Broadcast Music Incorporated and American Society Composers and Publishers which serve the same function of licensing and collecting creative royalties on works of music played in live public performance and recordings. IATSE : International Association of Theatrical and Stage Employees.: Normally these people are found on live theater stages working with sets, props, lighting and other theatrical gear. However, they may also be the union representing the same group of workers as IBEW. IBEW : International Brotherhood of Electrical Workers. IBEW has a special chapter for engineers, camera operators, audio engineers, video engineers, lighting designers and technicians, video editors and any other technicians or electricians who work in television production. IBEW members are employed by television stations, some cable companies, some corporations and some production companies. SAG : Screen Actors Guild which represents talent. Originally, this union represented actors working in the motion picture industry, but in recent years they have represented other talent areas
UNIXAn operating system developed by Bell Laboratories that supports multiuser and multitasking operations
UNMA - Unified Network Management Architecture(AT&T)
UplinkAn earth station that transmits a radio frequency signal to a communications satellite. The transmitting facility, or uplink, consists of a large dish-shaped antenna and high-power amplifiers. The uplink is like the transmitter of a radio or television station, except that it concentrates it signals in one direction by means of a parabolic dish antenna that delivers a strong pinpoint signal to a specific satellite in space
UploadCopy a file from your computer to a host system. Upload is the term used for sending information over a network. Download refers to receiving information off a network. To save on connect time charges users often download information on to a data disk, and then work with it off-line
URL - Uniform Resource LocatorA standard for writing a text reference to an arbitrary piece of data in the WWW. A URL looks like "protocol://host/localinfo" where protocol specifies a protocol to use to fetch the object (like HTTP or FTP), host specifies the Internet name of the host on which to find it, and local info is a string (often a file name) passed to the protocol handler on the remote host
UsenetAn anarchic network of sorts, composed of thousands of discussion groups on every imaginable topic
Usenet NewsgroupDiscussion group on one topic
User nameOn most host systems, the first time you connect you are asked to supply a one-word user name. This can be any combination of letters and numbers
UUCP - Unix-to-Unix Copy ProgramA method for transferring Usenet postings and e-mail that requires far fewer Net resources than TCP/IP, but which can result in considerably slower transfer times


VERY HIGH FREQUENCY (VHF)The part of the radio spectrum from 30 to 300 megahertz, which includes TV Channels 2-13, the FM broadcast band and some marine, aviation and land mobile services.
VIDEO DESCRIPTIONAn audio narration for television viewers who are blind or visually disabled, which consists of verbal descriptions of key visual elements in a television program, such as settings and actions not reflected in dialog. Narrations are inserted into the program’s natural pauses, and are typically provided through the Secondary Audio Programming channel.
Vehicle Payphonesee payphone
Video DistributionEquipment used in the provisioning of broadcast distribution services
Video-over-IPa one-way telecommunications service that allows video images and audio to be transmissed to one or more locations using the Internet protocol, or a two-way telecommunications service that allows live video images and speech of participants in a session, such as a conference, to be transmitted between two or more locations using the Internet protocol
Voice Applicationany application or service which relies upon voice communications, including PSTN voice, also known as POTS ("plain old telephone service"); features, such as voice mail; services, such as teleconferencing; and audiotext
Voice Backbonethe set of all network connections established between the toll and tandem and toll-tandem switches that move aggregated voice and fax traffic between PSTN terminals, regardless of the protocols or equipment or facilities used to do so. Voice backbones are measured as series of switch-to-switch links, where each link is assigned a discrete capacity based on the real or average estimated capacity (in Mbps) dedicated to moving voice traffic across that link
voice wirelinefixed user access to the PSTN over a PSTN-interconnected network access line which allows direct-dial communications to be established, regardless of whether the facility is used for voice, fax, dial-up Internet, or other services carried from customer premise to a switch in the 0-4000 KHz range. Voice wireline service may be provisioned over traditional telco copper, coaxial cable, fixed wireless, and other circuits. See also local calling area
Value Added Network - VANA data network operated in the U.S. by a firm which obtains basic transmission facilities from the common carriers, and adds value such as error detection and sharing and resells the service to users. Telenet and TymNet are examples of VANs
Vector QuantizationCompression coding technique that uses block processing to exploit redundancies within a frame. For example, if the blue sky background within a frame is one constant color, one pixel of that color is all that needs to be stored. Quick duplication of the pixel by vectors (usually 8 x 8) occurs when decompressed and displayed on a monitor
VeronicaAn information agent that searches a database of Gopher servers to find items that are of interest to the user
VFVoice frequency
ViAn extremely powerful Unix editor with the personality of a junkyard dog. Muchbeloved by many Unix aficionados
VideodiscInformation stored on an optical disc is retrieved via laser technology (versus a stylus or needle). The most commonly known optical disc is the audio compact disc. 12" or 8" in diameter optical disc; requires laserdisc player; may contain up to 54,000 still frames or 30 minutes of full motion video on each side (or some variation of each); stores information in analog format. Their use and popularity has been largely eclipsed by VCRs using magnetic videotape cassettes. Levels of Interactive Videodisc Systems: Level I : A videodisc player with the following capabilities: still/free frame, picture stop, chapter stop, frame address and two audio channels. Level I videodiscs have limited memory and limited processing power. Level II : A videodisc player with the capabilities of Level I, plus programmable memory and improved access time. Level III : Level I or II players combined with an external computer and/or other peripheral processing device. Level III IVD systems may have two monitors - one for the video and one for the computer - or may display the video and computer screens on a single monitor. Level IV : Combines computer and videodisc technologies into one piece of equipment. Too expensive for most commercial uses, it is used almost exclusively by the military
VideoA term pertaining to the bandwidth and spectrum of the signal which results from television scanning and which is used to reproduce a picture. Video Camera: A camera which converts images to electrical signals for recording on magnetic tape or live transmission. Videodisc A record-like device storing a large Telecommunications Glossary/91 amount of audio and visual information that can be linked to a computer; one side can store the pictures and sounds for 54,000 separate television screens
Video DisplayPresentation of the TV signal can be as simple as using a 19" TV receiver or as elaborate as large screen projection costing $200,000. The ideal lies somewhere in between. Analyze the room, physical layout, anticipated audience size, and AV support staff. In general, the larger the screen, the better. Projected images produce greater psychological impact, and help to dispel a viewer's feeling that he or she is watching TV. A general rule of thumb that has been suggested concerning minimum screen size is to figure no more than one viewer per diagonal inch. A 19" set would accommodate 19 viewers. This may not always be the case and it does not provide the larger-than-life experience that may be more effective in communicating the message
VideotapeA plastic, iron oxide-coated tape of various widths from 1/4" to 2" for recording and playback of video and audio signals and additional technical code information
Video TeleconferenceA meeting involving at least one uplink and a number of downlinks at different locations. Electronic voice and video communication between two or more locations. It can be fully interactive voice and video or two-way voice and oneway video. It includes full-motion, compressed, and freeze-frame video
VideotexThe generic term used to refer to a two-way interactive system(s) for the delivery of computer-generated data into the home, usually using the television set as the display device. Some of the more often used specific terms are "viewdata" for telephone-based systems (narrowband interactive systems); "wideband broadcast" or "cabletext" for systems utilizing a full video channel for information transmission; and "wideband two-way teletext" for systems which could be implemented over two-way cable television systems. In addition, hybrids and other transmission technologies, such as satellite, could be used for delivery of videotex services on a national scale
ViewdataGeneric term used primarily in the U.S. and Great Britain to describe twoway information retrieval systems based on mainframe computers accessed by dumb or intelligent terminals whose chief characteristic is ease of use. Originally designed to use the telephone network, viewdata in the U.S. is being implemented over other distribution media such as coaxial. Viewdata's salient characteristic is the formatting, storing, and accessing of screens (sometimes called frames or pages) of alphanumeric displays for retrieval by users according to a menu or through use of keyboard search. A two-way form of videotex
Virtual Private NetworkUse of the public switched telephone system to provide a capability similar to that of a private network
Virtual Reality - VRLoosely defined as putting users into a computer-generated environment, rather than merely reacting to images on a display screen. Full immersion VR can include a helmet that senses head movement and changes the view seen through small TV screens mounted in front of each eye along with gloves that allow users to touch objects in the virtual world
Virtual SpaceRefers to a type of videoconference in which each participant is assigned a separate camera and is seen on a separate monitor, large screen or assigned spatial area
VLSIVery large scale integration
Voice ActuatedEquipment activated in response to a voice. A voice-switched microphone is activated by a voice. In voice-switched video cameras are activated by voice to send a picture of the speaker
Voice MailProducts record, store and forward voice messages from one electronic mailbox to another by using single commands from any touch tone phone
Voice-OverWords spoken by an off-camera narrator - over the video
Voice-Switched MicrophoneMicrophone that is activated by a sound of sufficient amplitude; generally allows only one person to speak at a time
Voice-Switched VideoType of video conference in which the cameras are activated by voice signals to send a picture of a particular person in the group. Not all participants can be seen at any one time in contrast to continuous presence video
Volatile MemoryA storage medium in which information is destroyed when power is removed from the system
VSAT - Very Small Aperture TerminalSmall earth stations with a satellite dish usually 4 to 6 feet (1.2 to 1.8 meters) in diameter used to receive high speed data transmission; can also transmit slow- speed data. A VSAT uplink for compressed video a C-Band frequencies is approximately 4.5 meters in diameter for most satellite applications
VT100Another terminal-emulation system. Originally, a dedicated terminal built by DEC to interface to mainframes. Supported by many communications program, it is the most common one in use on the Internet. VT102 is a newer version
VTR - VCRVideo tape recorder or video cassette recorder. Equipment capable of recording video. All video equipment is not equipped to record as it requires recording heads to accomplish


WAIS - Wide Area Information ServiceA distributed text search system based on a standard (Z39.50) that describes a way for one computer to ask another to do searches for it. It looks at the content of files (not just the titles)
WANWide Area Network (see LAN)
WATS LineWide Area Telecommunications Service A type of telephone service in which subscribers pay a base rate rather than a charge per call. An in-WATS line allows anyone in a designated area to phone an 800 number and pay nothing for the call. An out-WATS line allows users to place outgoing long-distance calls. Wavelength Multiplexing: Transmitting individual signals simultaneously by using a different wavelength for each signal. Synonymous with frequency division multiplexing. Whois: An Internet program which allows users to query a database of people and other Internet entities, such as domains, networks and hosts, kept at the NIC. The information for people shows a person's company name, address, phone number and e-mail address
WildcardsSpecial characters such as * and ? that can stand in for other characters during text searches in some programs. The * wildcard generally means "match any other characters in this spot," and the ? generally means "match any other character in this spot."
WipeOptical effect in which the picture appears to have been wiped from the screen; i.e. from left to right, top to bottom
Wireless CableUses microwave frequencies to transmit programming to a small antenna (about the size of an open newspaper) at subscriber homes
World Wide Web - WWWThe web of systems and the data in them that is the Internet. Presents information in a user friendly hypertext format. WWW displays pages of information, with links to other pages. Mosaic is the program that really makes Web materials come alive. Different systems display the links differently, by highlighting the link items or by putting a code (such as a number in brackets) after the item. Others put the link in boldface or in color
WorldWindowOffered by the Washington University Libraries in St. Louis, MO, a gateway to dozens of login services. Telnet to (no login needed)
WORM - Write Once Read ManyA type of permanent optical storage which allows the user to record information on a blank optical storage disc. Information may be added until the disc is full, but not erased or changed
Word ProcessorA computer-based typing and text-editing system
WorkstationComputers that are generally targeted at technical users, interface over a network easily, often run UNIX, come standard with more compute power than PCs and are capable of fast graphics. Distinctions between high-end personal computers and Telecommunications Glossary/94 workstations are blurring. For high-end animation work such as 3-D logs, morphing or animated characters, workstations provide the compute power and graphics performance the animator needs. Workstations are used for computer-generated imagery (often called CGI) because they take less time than PCs to render images
WrapThe end of a program or production sequence, as in, "That's a wrap
WraparoundLocal activities prior to, in the midst of, or following a teleconference to focus the content toward outcomes and ideas which can directly assist the participants
WAPireless application protocol. A transaction-oriented specification for sending and receiving information, content, and service-specific data over wireless networks. French: WAP
Wavelengththe distance between a point on one lightwave and the point of corresponding phase on the following lightwave, measured in nanometers. In conjunction with a technique called wavelength division multiplexing, lightwaves can be divided into wavelength portions and deployed as a series of communications channels similar to virtual clear-channel circuits. Although the bandwidth supplied by these channels is a function of the equipment deployed at their ends, most commercial wavelength products are offered in standard bandwidth increments, especially 2.5 Gbps and 10 Gbps. French: longueur d'onde
WDM ( Wavelength Division Multiplexing)Is a method of transmitting multiple signals at various wavelengths of light simultaneously over a single fibre optic strand; this is utilised to improve the capacity of the fibre. French : WDM (multiplexage en longueur d'onde)
Wholesaleprovision of a telecommunications service or facility to a service provider, regardless of whether that service provider rebills the service or facility to another entity, or uses that service or facility internally to support the services it bills. French: de gros
Widebandon a point-to-point telecom link, two-way capabilities with speed in at least one direction of greater than 64 Kbps up to and including 1.544 Mbps. See also bandwidth, broadband, narrowband. French: large bande
WiFi (802.11)a limited-range wireless networking protocol based on the 802.11 family of standards; uses spectrum in the 2.4 GHz range to exchange data at broadband speeds. French: WiFi (802.11)
Wirelessa device or system which performs one or more telecommunications applications without using wires to communicate between nodes, usually by relying on radio frequencies instead. French: sans fil
Wireless Number Portability (WNP)Allow consumers to switch between telecommunications service provider, either wireline or wireless, while retaining their telephone number. French : Transférabilité des numéros de services sans fils (TNSSF)
Wireline Voicesee voice wireline. French: vocal filaire


X.25Set of packet-switching standards published by the CCITT. An international
standard for control of data communications between two or more computers or terminals using packet-switching technology
XMODEMA common file transfer protocol


YanoffScott Yanoff publishes a regularly updated on-line resource guide. To find out how to get a copy finger [email protected]
Yellow BookThe physical specification for CD-ROMs. See CD-ROM
YMODEMAnother common file transfer protocol


zipThe filename extension used by files compressed into the ZIP format common on PCs
ZMODEMThe fastest and most popular file transfer protocol