Fiber Optics Illustrated Dictionary - Part 18 potx

A version of Carrier Sense Multiple Access that is used in Ethernet systems in association with Media Access Control MAC pro-tocols to integrate collision detection with time-di-vision m

Fiber Optics Illustrated Dictionary

cardAnelectronic printed circuit board, especially

one that is easily dropped into acard slotby a dealer

or consumer See printed circuit card, punch card

card hopperInmechanisms that hold and feed punch

cards, the holder in which the cards are stacked next

to the feed mechanism for processing See card stacker

Card Issuer Identifier CodeCnD A calling card

identification scheme There are restrictions on which

carriers can issue/use cnD cards

card slotAslot-shaped data connector within an

elec-tronic system for the insertion ofprinted circuit board

peripherals Cards frequently consist ofgraphics

con-trollers, drive concon-trollers, serial and parallel ports,

network connectors, and others PCI is a common

format for computer card slots See edge connector,

printed circuit board

card stackerInmechanisms that hold and feed punch

cards, the exit tray in which the cards are stacked

af-ter processing There may be several of these, with a

card sorter determining the destination stacker from

holes in the cards See card hopper

Cardano, Girolamo (1501-1576)Also known as

Hieronymus Cardanus, Cardano was an Italian

math-ematician, physicist, and physician to kings who

authored many important historic publications,

in-cludingDe subtilitate (On subtlety, 1550),

describ-ing the accumulated knowledge about amber, with a

definite statement that the properties oflodestone and

amber differed in significant ways He further

de-scribed these differences He also proposed the

im-portant mathematical notion of imaginary numbers

and made a systematic study of probabilities See

amber, lodestone

Girolamo Cardano - Magnetism Pioneer

A multitalented pioneer in mathematics and

phys-ics, Girolamo Cardano contributed important insights

to our understanding of magnetism (e.g., properties

oflodestone) and theoretical mathematics in the 1500s.

CardBus A32-bit computer data bus designed for

use with PCMCIA cards The CardBus was designed

to succeed the PC Card standard See Personal

Com-puter Memory Card Interface Association

cardiode pattern Adiagrammatic representation of the directional response of various transmitting and receiving devices: antennas, speakers, etc It derives its name from the symmetrical, heart-shaped pattern that is typical See antenna lobe

Carnegie-Mellon UDiversityThis U.S educational institution is known for many contributions to tele-communications One ofthe more familiar is the An-drew File System (AFS) used on computer networks More recently, developers have created a working, campus-wide wireless data communications system which serves as a model for similar installations else-where and AFS is evolving into a powerful, distrib-uted network protocol with a new name and some in-teresting new capabilities

carrier 1.A wave of constant or known amplitude, frequency, and phase, which can be modulated by changing one of these characteristics See carrier wave, carrier frequency, Tl 2.Anentity that can carry an electrical charge through a solid 3 An in-formation-providing radiant energy from space The four known categories ofcarriers are electromagnetic radiation, solid bodies, elementary cosmic rays, and gravitational waves

carrier, communicationsA provider of communi-cations circuits.Common (usually the local phone company) andprivatecarriers are distinguished by degree ofregulation and right to access ofservice by the public The designation ofcommunications car-rierwas intended to encompass companies with their own transmission facilities, as opposed to companies that lease or buy equipment or services for resale, but the general public often uses the phrase more loosely

to include all long-distance companies

carrier, GPS AGPS-related radio wave with at least one characteristic (such as frequency, phase, ampli-tude) that can be varied (modulated) from a known reference value See Global Positioning Service Carrier Access CodeCAC See Access Code carrier bandArange ofadjacent frequencies that can

be modulated to carry information, such as radio broadcast waves (without a carrier wave, multiple frequencies could not be transmitted without signal overlap and disruption) See band, carrier, carrier wave, modulation

carrier bypassAphone service provider direct-con-nect link to the customer's lines, bypassing the local phone carrier Some long-distance companies provide services through a carrier bypass in order to provide faster service or less expensive service by avoiding Carrier Common Line Charges See Access Charge Carrier Common Line ChargeCCLC A charge paid by phone services providers to a primary car-rier for using their switched network lines Typically paid by long-distance providers See Access Charge, carrier bypass

carrier detectCD.Asignal generated by a modem that operates over phone lines to indicate whether the phone carrier is present and the line can be dialed Many modems have an LED to indicate the presence ofthe carrier signal The command to the modem for carrier detect is typically &Cl

intended to be modulated by the wave containing the

information See carrier wave 2 In the Global

Posi-tioning System (GPS), the frequency of the

unmodulated fundamental output of a radio

transis-tor 3 The reciprocal of the period ofa periodic

car-rier See center frequency

Carrier Identification CodeCIC A short code to

identify uniquely a secondary phone service carrier

for routing and billing It was formerly three

charac-ters, but the Industry Carrier Compatibility Forum in

1988 and Bellcore in 1989 informed the Chiefofthe

Common Carrier Bureau that four characters were

needed to meet increasing demand The numbers are

issued by the North American Numbering Plan

Ad-ministration (NANPA) to authorized entities The

ex-pansion from three to four digits was termed the Plan

of Record (POR) The implementation of this plan

would not be trivial as it involved administrative

changes and expenditures on the part of Local

Ex-change Carriers (LECs) and Ex-change-over expenses to

anyone publishing materials with CICs (directories,

letterheads, marketing materials, etc.) It also required

procedures and priorities for conserving and reusing

scarce CIC resources

By the mid-1990s, Bellcore began

assigning·four-digit Feature Group D CICs In 1998, this was

fur-ther changed to a prefix (e.g., "1 0+1Oxxx")followed

by the number, thus bypassing the subscription

car-rier (which would use the prefix code" 1") See

Ac-cess Code, North American Numbering Plan

carrier select keysButtons included on a phone

(usu-ally a payphone) to provide the caller with a quick

way to select a long-distance provider, thus not

hav-ing to key in extra digits for access codes

carrier selectionSelection by a phone customer of

a long-distance provider, usually done at the time of

ordering the service, but it can be changed at any time

Ifyou select a primary long-distance carrier, you will

be able to access the service by dialing "1" plus the

number For alternate long-distance companies, you

have to enter additional digits or access codes to

com-plete a call There are many long-distance companies,

each offering better features and lower prices than the

next Evaluate these carefully before switching

ser-vices, as there may be inconveniences, hidden

charges, or limitations that are not apparent from the

advertising literature and that may result in service

that is limited and not necessarily cheaper in the long

run See Access Code, carrier bypass

carrier senseThe capability of a station to

continu-ously monitor other stations to see if they are

trans-mitting See Carrier Sense Multiple Access

Carrier Sense Multiple AccessCSMA

Alisten-and-send protocol used on local area networks (LANs)

A system readying to transmit first probes the

net-work to see if the line is clear; in other words, it

en-sures that another workstation is not transmitting If

the coast is clear, it sends the transmission This

pro-tocol does not guarantee that collisions don't occur;

it simply reduces the likelihood ofan immediate

col-lision Various versions of CSMA exist to enhance

and avoidance

Carrier Sense Multiple Access with Collision AvoidanceCSMA/CA A version of Carrier Sense Multiple Access that is used in Ethernet systems in association with Media Access Control (MAC) pro-tocols to integrate collision detection with time-di-vision multiplexing (TDM) It aids in improving ef-ficiency in CSMA systems See Carrier Sense Mul-tiple Access

Carrier Sense Multiple Access with Collision De-tectionCSMA/CD A version ofCSMA with added traffic flow control capabilities to detect collisions,

in order to increase the efficiency of flow of infor-mation on a local area network (LAN) CSMA/CD

is not ideal for all implementations In satellite com-munications, for example, the transmitting Earth sta-tions cannot engage carrier sensing on the uplink due

to its point-to-point nature See Carrier Sense Mul-tiple Access

carrier shiftingA technique of moving an entire modulated wave sequence in a positive or negative direction with respect to its midpoint, without chang-ing the overall shape of the envelope Carrier shift-ing is often used to manipulate mathematically a wave

or to recreate a wave based upon only partial infor-mation (e.g., sideband) See phase shift keying carrier shifting faultAnundesirable condition in transmitting a modulated carrier wave, in which the envelope, the range of amplitude-modulated signals above and below the midpoint of the waves, is un-balanced

carrier signalA continuous radiant wave that can be modulated to add information to the wave Carrier signals are modulated in a variety of ways; the two most familiar are amplitude modulation (AM) and frequency modulation(FM).One ofthe first research-ers to search for a way to add information to a carrier wave was R Fessenden, an American inventor who devised the hot-wire barretter and a high-frequency wave generator in 1901 Later,1.Carson studied the mathematical properties of carrier signals and pro-posed ways ofcarrying information by manipulating and recreating the signal at the receiving end, thus saving transmissions bandwidth See Carson, John Renshaw; Fessenden, Reginald Aubrey; modulation; single sideband

carrier synchronizationIn radio broadcasting, a carrier wave is used to carry a signal through a pro-cess called modulation, wherein information is added

to the carrier wave Various means of sending the modulated wave have been developed, some ofwhich send only the sidebands, some ofwhich send one side ofthe signal and recreate the other, etc Consequently,

at the receiving end, the receiver has to be designed

so it can properly process the type of wave that is being received In some cases, this situation involves the creation ofa reference carrier that is synchronized with the received signal See Carson, John R.; single sideband

carrier to interference ratio CIR A quantitative description of the effective transmission in relation

Fiber Optics Illustrated Dictionary

to the (undesired) interference affecting that

transmis-sion This ratio is of special interest to wireless

com-munications engineers in designing transmissions

components such as antennas and transceiving

equip-ment It is of increasing importance as vendors seek

to increase the capacity of existing systems without

degrading the signal to the point that the customers

are unhappy with the service

carrier waveA single-frequency wave that carries

the transmission by being modulated by another wave

containing the information A carrier wave provides

multiple channels and a means to reduce signal

over-lap through multiplexed broadcast waves See carrier

carrierless amplitude and phase modulation CAP

modulation Acoding technique, based upon

quadra-ture amplitude modulation, usedinDigital Subscriber

Line (DSL) transmissions See discrete multitone,

modulation, pulse amplitude modulation

CARS See Cable Television Relay Service Station

Carson, John RenshawA mathematician and

re-searcher at Bell Laboratories who contributed

math-ematics fundamentals related to modulation of

com-munications waves that provided a way to recover the

whole band from sideband transmissions In 1915, he

demonstrated that separate channels could be carried

on each ofthe sidebands ofa modulated carrier wave

In 1922, he provided a mathematical description of

frequency modulation (FM) (and is somewhat

infa-mous for having disagreed with E Armstrong about

the feasibility ofFM transmissions) He was awarded

the Franklin Institute Cresson Medalin 1939 See

Armstrong, Edwin Howard; Carson's Rule

Carson's RuleA method for calculating the

mini-mum bandwidth of a frequency-modulated signal

needed to transmit the desired communication A

larger number of subcarriers will necessitate a wider

Carson's bandwidth Named after John R Carson

CarterfoneA commercial device developed in the

1960s for acoustically connecting two-way mobile

radio communications to a telephone network system

Developed by Thomas Carter, who battled for the

right to connect into the public phone network, the

system became known through an important

judg-ment by the Federal Communications Commission

(FCC) Carter didn't sell many of the devices, but

AT&T saw the precedence as threatening enough, in

terms ofits implications for other vendors, to obstruct

its use See Carterfone Decision

Carterfone DecisionA 1968 landmark judgment by

the Federal Communications Commission (FCC) in

which existing interstate telephone tariffs that

pro-hibited subscribers from attaching their own phone

equipment to existing phone lines was struck down

Carter Electronics had sought since 1966 to

acousti-cally interconnect its private mobile radio systems to

the national exchange network through a

voice-acti-vated system that started the radio transmitter In

pur-suing its own right ofaccess, Carter Electronics paved

the way for other companies as well and, in a sense,

foreshadowing the divestiture ofAT&T

As a result of the Carterphone Decision,

manufac-turers other than Western Electric, which had

exclu-sive arrangements with AT&T, no longer were pre-vented from using the resources, and the interconnect industry was born See Carterfone, Hush-a-Phone de-cision

cartridgeA common type of magnetic removable data storage that works somewhat like a floppy dis-kette but is physically larger in size and significantly higher in storage capacity Cartridges commonly hold between 200 Mbytes and 1 Gbyte of data uncom-pressed With the introduction of super-capacity disks, 3.5" floppies that can store more than 100 Mbytes ofdata, the discrepancy between low-capac-ity cartridges and high-capaclow-capac-ity floppies is less than low-capacity floppy drives Rewritable CDs are now beginning to compete with cartridges as backup stor-age devices due to the less volatile nature ofthe data Carty, John J.(1861-1932) Chiefengineer ofAT&T

in the early 1900s after serving as the head of West-ern Electric's cable department Carty developed the frrst two-wire telephone circuit and the phantom cir-cuit, through which three conversations could be transmitted at one time over two pairs ofwires West-ern Electric purchased the rights to Lee de Forest's

Audion, a three-electrode tube, in time for Carty to fulfill a promise he made in 1909 to provide a trans-continental telephone service to the U.S west coast

by 1914 See AT&T, phantom phone

Carty, John J., Award for the Advancement of ScienceAtriennial award for noteworthy and distin-guished accomplishment in science This award has been directed towards a different field every three years since 1932 It was established by AT&T CAS 1 Centralized Attendant Service Acentralized group ofoperators servicing systems which may have

a number of branches within a region 2 See chan-nel associated signaling 3 See Communications Applications Specification

cascadeTo arrange or pattern into a series or succes-sion of steps or stages, each dependent upon, or de-rived from the preceding, often in a falling or down-ward hierarchy Computer menus, file systems, ap-plications windows, and other graphical and logical structures are often developed with a cascade struc-ture Text editing applications sometimes have tele-scoping and cascading outline capabilities Cascad-ing principles and properties are now beCascad-ing studied with relation to quantum effects and harnessed for commercial applications See quantum cascade laser CASE computer-aided software engineering, com-puter-assisted software engineering

case sensitive1.Computer softwaredataor processes

in which the case (lower or upper) is considered sig-nificant to the meaning of the text For example, file names on Unix systems are case sensitive; that is,

"MyFile.txt" is different from "myfile.txt" Case sen-sitive file names result in a greater range of descrip-tive naming possibilities MS-DOS systems are case insensitive AmigaOS is partly case-sensitive, forgiv-ing about case when traversforgiv-ing directories in the shell, but allowing file names that can be distinguished from one another by case 2 In word processing, search and replace routines can usually be configured to be

your needs 3 On the Web, URLs are case sensitive,

but for the convenience ofusers many browsers will

resolve the cases in a forgiving manner, to load a Web

page even if the case is misspecified This feature is

not characteristic ofall browsers, so it's usually

bet-ter to type in the case correctly

case sensitive passwordFor access to secure

com-puter systems, most password fields require an exact

match, hence are case sensitive, in order to provide a

greater variety of possible passwords and thus

in-creased security Case sensitivity also increases the

total number ofpossible passwords, which is

impor-tant if it is a multiuser environment with a limit on

the number of characters in the password (e.g., eight

characters)

Cassegrain antenna, Cassegrainian antenna A

parabolic antenna arrangement in which the feed is

located near the vertex of a concave surface of the

main reflector, and a secondary reflector is located

near the focal point and aligned to be within the

fo-cus of the main reflector A beam is thus redirected

from the feed unit through the secondary reflector to

the main reflector to radiate a beam that is parallel to

the axis of the main reflector A Cassegrain feed is

one type of arrangement; hom feed is another

Cas-segrain antennas require more careful alignment and

more parts than a hom feed antenna and thus tend to

be used in higher end, more expensive applications

Due to the redirection of the reflection, they stay

cooler than hom feed arrangements and are thus

suit-able for hotter climates See antenna; hom feed;

para-bolic antenna; Ramsden, Jesse

Cassegrain, Guillaume(dates unknown) Apparently

a French founder and sculptor who developed a

cen-ter mirror telescope even before Newton constructed

a reflecting telescope In 1672, Cassegrain proposed

using a main mirror with a hole in the center, with a

smaller hyperboloid mirror to reflect back the image

through the hole to an eyepiece This arrangement

results in a compact design and minimal spherical and

chromatic aberrations in the image.Itis the same

general configuration of some of the advanced

tele-scopes of today See Cassegrain antenna

cassette tapeA portable recording and playing

me-dium consisting of a long narrow magnetic tape

wound onto reels protected by a roughly rectangular

plastic case

Cassette tapes come in a variety of tape widths and

are used for both sound and video

Some audio tapes are wound onto the reel in a loop

to enable continuous playing, but most are manually

turned over or mechanically rewound Cassettes are

commonly used for consumer audio and backup and

archiving ofcomputer data Very small cassette tapes

are used in answering machines and small tape

re-corders designed for maximum portability (and, in

some cases, minimum visibility) Cassette tapes for

consumer audio almost completely replaced

reel-to-reel tape, then began to be supplanted by audio CDs

and other digital audio technologies See CD, DAT,

leader, reel-to-reel

solar system and send back information to be evalu-ated by scientists to teach us more about our plan-etary environment and the universe The Cassini spacecraft has many tasks to perform on its way to the planet Saturn Flyby targets include Venus, Earth,

~~;~~~~;~~~~~:;~~~~t~~~;~i~:~b~f~<'11 maneuvers and flybys needed to take it on its seven year journey to Saturn The telecommunications and guidance systems associated with the Cassini mission are some of the most sophisticated to date and will teach us much about how far and how well we can transmit information to and from the comers of the Galaxy

castellationAnindented pattern or surface ofa regu-lar, repeated nature For example, the battlements on castles are castellated Castellated protruberances, or thin pads ofconductive materials, are often incorpo-rated into the edges ofelectronic circuit boards to pro-vide contact points for electrical connections Grat-ings are often castellated components

cat, Catabbrev. category Incabling,Category,or

Catfollowed by a number denotes industry-specific cabling standards See category ofperfonnance

CAT 1 Call Accounting Terminal.AnAT&T term for a microprocessor-equipped device that records call activity in order to provide automated account-ing information 2 See computer-aided teachaccount-ing, computer assisted instruction 3 See Council for Access Technologies

catadioptric devicesDevices that utilize both opti-cal reflection and refraction to control the travel of light through the device, often to produce an image for viewing or transission Depending upon the strument, the catadioptric configuration may be in-tended to shorten the length of the barrel of a view-ing device or process the light signal as it is beview-ing reflected and refracted Catadioptric principles are used in a variety of astronomical telescopes, robot-ics imaging technologies, and some digital video cam applications

CatarraSee PDA marcrobrowser, SoftSource Corp

category, wiringSee category ofperformance

category of performanceCabling and component standards that have been defined to promote and fa-cilitate intercompatibility ofproducts from different vendors These standards are widely used in the phone and computer network industries, especially Cat 5

The categories ofperformance focus on the through-put of the transmissions rather than the specific ma-terials used to construct individual cables They are self certifying in the sense that the vendor is respon-sible for testing and maintaining quality and manu-facturing standards to provide the performance cat-egories detailed in the Catcat-egories chart

catbode(symb - K) 1.The negative terminal of an electrolytic cell 2 The positive terminal of current-supplying primary cell 3.Ina moving electron sys-tem such as an electron tube, the electron-emitting portion, directed toward an anode, often a thin metal

Fiber Optics Illustrated Dictionary

plate, usually passing through a controlling grid The

electron beam-emitting end of a cathode-ray tube

(CRT) See cathode-ray tube, phototube,

photomul-tiplier tube

Cathode-Ray Tube - Basic Parts

Cathode in Electron Tube

The cathode is one of the three essential elements

ofan electron tube, emitting the electrons that are

at-tracted to the anode In this tube, the filament acts as

the cathode. The movement of the electron beam across the

dis-play surface excites the phosphors so that they selec-tively light up (fluoresce) and remain visible for a few moments The sweep of the beam is very fast so that perceptually humans will 'see' the entire frame as one image rather than as a series of constantly refreshed lines

Sometimes a grating called ashadow maskis inserted between the beam and the coating to further control and focus the beam to provide a crisper display Cathode-ray tubes can beshort persistenceorlong persistence.Long persistence means the phosphors remain lit for a longer period of time, and the screen may not have to be refreshed as often to keep an im-age visible

The refresh rate on most current monitors is 60 frames

Cathode-ray tubes are essential components in many types ofelectronics devices They are widely used as display devices for televisions, radar scopes, oscillo-scopes, computer monitors, etc This diagram ofa his-toric electromagnetic-deflection cathode-ray tube pro-vides an example ofthe basic, essential components.

phosphor coating on inside of tube

deflecting coils anodes

cathode rayAnionized region, composed ofa stream

of electrons influenced by an electric field,

emanat-ing from a cathode See cathode-ray tube

cathode-ray tubeCRT A display device consisting

ofa closed tube ofglass with the air removed; it

con-tains an electron-emitting gun at one end and a coated

surface at the other The cathode-ray electron beam

emanates from the cathode and passes through a

mag-netic field that controls the beam By sweeping across

the coated inside surface of the glass, aframe is

fonned on arasterdisplay and avectoris formed on

avectordisplay, either ofwhich can be seen through

the glass from the outside

cathode (filament)

Categories of Performance Category Transmission Rate Notes

Cat 1 Not used

Cat 2 Not used

Cat3 Upto16megahertz 24-gauge wire Typically used in voice communications and

lower end data communications, such as Token-Ring and 10-Mbps Ethernet networks

Cat4 Up to 20 megahertz Digital voice communications and data networks, e.g.,

Token-Ring

Cat 5 Up to 100 megahertz 24-gauge wire with more stringent fabrication requirements than

Cat 3 (e.g., better shielding) Typically used in higher end data communications and high-grade or digital voice applications, particularly high-bandwidth ones such as videoconferencing Examples include FDDI, lOOBase-T, lOO-Mbps Token-Ring or Ethernet See twisted pair for a diagram

and not flickering to the human eye Color CRTs

typi-cally have three beams, red, green, and blue (RGB)

The cathode-ray tube is fragile and large

(regretta-bly) and is typically encased in a protective console

It is not advisable for laypersons to open the back of

a CRT device, as there is a danger of electric shock

from the stored charge CRTs were being used as

computer display devices by the early 1950s but did

not become regularly associated with

microcomput-ers until 1976 CRTs are commonly used for

moni-tors (computers, video editing, scopes) and television

screens See Crookes tube; flat panel CRT; frame;

Geissler tube; interlace; screen saver; shadow mask;

Zworykin, Vladimir Kosma

cathodic protectionIn many wiring installations,

bare wire is used, so corrosion is a significant

con-cern One of the ways to prevent corrosion and

buildup is by running a negative charge through the

wire to repel negative ion materials such as chlorine

CATNIP See Common Architecture for Next

Gen-eration Internet Protocol

CATS See Consortium for Audiographics

Telecon-ferencing Standards

CATVI.Cable Television Asystem that delivers

fre-quency-segmented television programming channels

to subscribers through physical cables, usually

75-ohm coaxial cables The full bandwidth of cable

is not typically used, partly due to the extent of the

subscriber's service and partly due to the insertion

ofnon-program-carrying guard bands that act as

sepa-rators to keep individual channel transmissions from

interfering with one another 2 Community Antenna

Television Alarge antenna, shared by a community,

to intercept broadcast stations that are not accessible

via small, individual antennas Sometimes

commer-cial communities (motels, resorts, condominiums)

will make arrangements to install a powerful antenna

and rebroadcast or channel the signals to individual

units In many cases, this will require a special license

as there are laws protecting broadcasters from

hav-ing their programs rebroadcast

catwhiskerAfine metal thread resembling the arched

shape of a cat's whisker, used in early radio wave

detecting crystal sets The catwhisker contacted the

crystal on one end and was secured to a metal

con-ductive support on the other end Some enclosed sets

used a catwhisker that was fixed in place at the

fac-tory Prior to the commercialization of crystal sets, it

was known as afeeler. See crystal detector

CAU See controlled access unit

CAY See constant angular velocity

cavityA depression, hole, indentation, or pit, which

may be ofany size.Invarious media, cavities

ofpre-cise characteristics are created in the surface so they

can later be used to deflect radiant waves or carefully

focused laser light beams The deflections pass into

some kind of pickup mechanism (read mechanism)

so the encoded information can be recreated and

pre-sented Thus, cavities are at the heart of many

opti-cal recording technologies, CDs, for example

cavity magnetronAnearly British innovation in radar

extremely short waves (microwaves) Thus, it was possible to design more compact antennas and im-prove the quality of the information and images that could be resolved through radar systems Smaller beam widths facilitated greater accuracy In tum, the smaller, more accurate radar technologies greatly in-creased the number and types of applications that were practical, making it possible to mount radars on boats and planes See magnetron

CDradioSee citizen's band radio

CDC See Canadian Broadcasting Corporation CDDS 1 Common Basic Data Set 2 See Con-nectionless Broadband Data Service

CDEMA Computer and Business Equipment Manu-facturers Association See Information Technology Industry Council

CDRAnATM traffic flow control concept See con-stant bit rate

CDS See Columbia Broadcasting System

CDSC See Canadian Broadcast Standards Council CDT 1 See Canadian Business TelecommUnications Alliance 2 Computer-Based Training See com-puter-assisted instruction

CDTA See Canadian Business Telecommunications Alliance

CDX Computerized Branch Exchange A commer-cial private telecommunications system trademarked

by the ROLM Corporation as their version of a pri-vate branch telephone exchange (PBX)

CDYD Call Before You Dig The warning on signs

by fiber optic cables to prevent contractors and other diggers from damaging underground installations CCD See Common Carrier Bureau

CCC 1 clear channel capability In communications, that portion of a data transmissions capacity that is available to users, the informational portion, above and beyond the various control and signaling trans-missions associated with the functioning ofthe tech-nology 2 Communications Competition Coalition ACanadian support and lobbying organization estab-lished to encourage Canadian telecommunications competition 3 Center for Corporate Communica-tions http://www.communicationsmgt.org/4.Com-puter Communications Club http://www.ccc.or.at/ CCD 1 See charge coupled device

CCI See co-channel interference

CCIA See Computer and Communications Industry Association

CCIR 1 See Centre for Communication Interface Research 2 See Comite ConsultatifIntemational des Radiocommunications

CCIRvideo standardSimilar to theEIARS-170a standard for color video, CCIR is a dominant video format used in Europe just as NTSC is standardized

in North America and Japan CCIR supports a verti-cal resolution of625 scanlines, 575 ofwhich are typi-cally displayed It is an interlaced format with two scans of the screen combining to create a conceptual frame The number of lines per field (two of which make up the frame) is 282.5 compared to 242.5 for RS-170a The effective resolution when conversion

Fiber Optics Illustrated Dictionary

with raster-based displays is desired is 768 (compared

to 640 for RS-170a) CCIR video is traditionally

transmitted over 75-ohm well-shielded coaxial cables

CCIRNCoordinating Committee for

Intercontinen-tal Research Networks Established by the U.S

Fed-eral Networking Council (FNC) and the European

Reseaux Associees pour la Recherche Europeenne

(RARE).CCIRN promotes international cooperation

and sponsors a number of working groups that meet

in different parts of the world

CCISSee Common Channel Interoffice Signaling

CCITT Comite Consultatif Internationale de

Telegraphique etTelephonique International Telegraph

and Telephone Consultative Committee.An

influen-tial United Nations-sponsored international

telecom-munications standards committee based in Geneva,

Switzerland It changed its name to lTU in 1990 See

International Telecommunication Union

CCITT Study GroupsThese subgroups, operating under the CCITT (now thelTD)study and make rec-ommendations for specialized areas of telecommu-nications See International Telecommunication Union

CCNR(telephone) call completion on no reply (e.g.,

as in ISDN Q.733 call completion services) CCPSee Compression Control Protocol

CCRSee current cell rate

CCSSee Common Channel Signaling

CCS/SS7Common Channel SignaVSignaling Sys-tem 7 See Signaling SysSys-tem 7

CCSNCommon Channel Signaling Network See Common Channel Signaling

CCT 1 Calling Card Table See unmatched call

2 See Consultative Committee Telecommunications

Common CD Formats

CD-Audio Compact disc audio Adigital sound representation standard that is incorporated into

CD-ROMs Conversion from digital to analog for listening occurs in the computing hardware

Also known as Redbook Audio.

CD-I Compact disc interactive.Aninteractive multimedia standard developed by Philips and

Sony CD-I players are designed to accept and playa variety of CD-encoded data and can typically be interconnected with a computer or TV playback system

CD-Plus Compact disc plus A standard developed by Philips and Sony that enables audio CD

players to play multimedia (graphics and sound) discs by skipping over the nonaudio segment that is stored on the frrst track

CD-R, CD-ROM R Compact disc recordable Aformat for read/write CD-ROM systems See compact disc

for a fuller description

CD-ROM Compact disc read only memory A standardized, widely used format for storing digital

information on small flat optical platters that are read with laser technology and played on

CD players See compact disc for a fuller description

CD-ROM A computer peripheral that reads, and sometimes writes, digital information to a compact

disc Most consumer CD-ROM drives are read only, although read/write drives are now under $300 and may soon be a consumer item A CD-ROM drive can be used to run applications, read text files, images (PhotoCD), and audio Many CD-ROM drives come with software to play audio CDs through a speaker

CD-ROM X Acompact disc read only memory extended architecture A fonnat developed by

Microsoft that enables the interleaving of audio and video, rather than recording them on separate tracks It requires a player that can understand the format If played on a regular player, the audio will not be detected and played

CD-RW CD recordable/rewritable technologies that became prevalent in the late 1990s and which

were almost immediately challenged by emerging DVD technologies

CD-UDF A standardized fonnat for CD-recordable (CD-R) media that enables a variable

packet-writing scheme to be used as an incremental approach to the recording of compact discs (CDs).Itprovides a means for easily recording files on a CD in much the same manner as

on a floppy disk

CD-V Compact disc video A standard for storing video images on compact discs that hasn't

really caught on.Itis being superseded by CD-XA which enables the interleaving of video and sound

CD-WO Compact disc write once A fonnat designed for mastering a CD The CD is then used

in-house or in limited quantities, or is sent to a duplication factory for mass production Drives that are able to write a master CD were once out of the price range of small companies and consumers, but they have dropped to below $300 and can now be used by software developers, composers, and small record companies to produce masters or small production runs of specialized recordings

tions Agency.

CCTVClosed Circuit TV See closed circuit broadcast

CCU 1 camera control unit 2 communications

control unit

CD 1 See carrier detect 2 See compact disc See

Common CD Formats chart.3 count down A

con-cept in broadcasting related to the signaling ofthe

be-ginning of taping, editing, or live broadcasting

CDASee Communications Decency Act

CDCSContinuous Dynamic Channel Selection

CDDISee Copper Distributed Data Interface

CDESee Common Desktop Environment

CDF See cutoff decrease factor

CDLCSee Cellular Data Link Control

CDMASee code division multiple access

CDMPCellular Digital Messaging Protocol

CDOSee community dial office

CDP 1 Cisco Discovery Protocol 2 Customized

Dial Plan

CDPDSee Cellular Digital Packet Data

CDPD Forum, Inc.A not-for-profit organization

established in 1994 to promote the development and

acceptance ofCellular Digital Packet Data (CDPD)

It supports vendors who develop and distribute CDPD

products and services http://www.cdpd.org/

CDRSee Call Detail Record

CDRH classificationsA series of classifications to

alert users of the dangers of incorrect use of

laser-based components that emit external beams (more

powerful lasers may be inside the assembly but must

not emit to the exterior ofthe device) The laser safety

classification categories are somewhat generalized

since the wavelength ofthe light is an additional

fac-tor controlling the influence of the beam and is not

specified for all categories

CDTcredit allocation In packet-switched networks,

such as OSI, CDT applies to transmission flow control

CDTACSee Consumer/Disabilities

Telecommuni-cations Advisory Committee

CDV 1 cell delay variation 2 See Compressed

CDVT

CEConnection endpoint 1 In ATM networking, a terminator at one end of a layer connection within a SAP 2 circuit emulation

CE MarkA sign that an object has been certified through the overseeing European regulatory body, the European Telecom Directive, and does not require further testing or approval within the individual par-ticipating countries The mark provides identification

of products that conform to certain specified safety, electromagnetic, and interoperability requirements

CE certification is required for all telecommunica-tions terminal equipment (TTE) sold in the European Union See Underwriters Laboratory, Inc

CEBusConsumer Electronics Bus A home automa-tion standard managed by the CEBus Industry Coun-cil and accepted by the Electronics Industry Associa-tion (EIA) CEBus specifies a common format for connectionless peer-to-peer communications over standard electrical wiring The CEBus HomePnP standard is a nonproprietary protocol based upon the lEA 600 open standard In terms of functionality, it

is similar in concept to the X-I 0 protocol in that it operates over 120-volt, 60-cycle home wiring CEBus is a two-channel specification, with one chan-nel assigned to realtime control functions, the other

to informational data It uses a CSMA/CD protocol that includes various error detection and retry func-tions, end-to-end acknowledgment, and authentica-tion The Powerline Carrier uses spread spectrum technology to bypass electrical impediments in home wiring, spreading the signal over a range offrequen-cies rather than using a single frequency See spread spectrum, X-IO

CEBus Industry CouncilCIC A users group sup-porting the development and use of interoperable CEBus-based home network automation technolo-gies http://www.cebus.org/

CEDARThe Center of Excellence for Document Analysis and Recognition An organization at the

CDRH Laser Safety Classification Categories Class Designation Notes

Class I EXEMPT Visible, low-powered lasers considered safe for viewing

Class II CAUTION Visible lasers in the 600 to 700 nm range at 1 mW or less Do not stare

directly at the beam or a reflection of the beam

Classlila DANGER Visible lasers in the 600 to 700 nm range at 5 mW or less Severe eye

damage; avoid eye exposure to the beam or a reflection of the beam Class IIIb DANGER Visible lasers in the 600 to 700 nm range at 5 mW or greater and

invis-ible lasers in the 700 to 900 nm range Severe eye damage; avoid any exposure to the beam or reflection of the beam Doesn't present fire haz-ard

Class IV DANGER High power lasers exceeding characteristics of Class III lasers They

present a variety ofdangers from eye and object damage to diffusion haz-ards, burns, and general fire hazards

Fiber Optics Illustrated Dictionary

State University ofNew York at Buffalo that provides

a number of interesting services including

informa-tional CD-ROMs

CEI In ATM networking, a connection endpoint

identifier

Celestri A downsized version of the original M-star

project, Celestri is a low Earth orbit (LEO),

geosta-tionary hybrid satellite system from Motorola In May

1998, the Celestri expertise and technology was rolled

into the Teledesic project, when Motorola Inc bought

in as a major partner See Teledesic

cell, ATM In asynchronous transfer mode

network-ing, a unit of transmission consisting of a fixed-size

frame comprising a header and a payload See

asyn-chronous transfer method, cell rate

cell, battery Minimally, a receptacle containing an

electrolyte and two electrodes arranged so the

elec-tricity can be generated from the cell by chemical

actions Development ofmodem cells stems from the

experiments of C.A Volta Two or more cells can be

combined to form abattery.See battery, storage cell

cell, mobile phone In mobile communications, the

basic geographic unit of a distributed broadcast

sys-tem, within which a low-power transmitting station

is located Roughly hexagonal in shape, depending

upon terrain Its size varies with available channels,

generally increasing as the radius of each cell

de-creases Cells are further grouped into clusters See

cluster, cellular phone, mobile phone

cell delay variation CDY.In AIM networking, a

traf-fic flow buffering and scheduling concept CDV

pa-rameters are associated with constant bit rate (CBR)

and variable bit rate (VBR) services and relate

qual-ity of service (QoS) information by indicating the

probability that a cell may arrive late See cell rate

cell delay variation tolerance CDVT In ATM

net-works, a traffic flow control mechanism that allows

cells to be queued during multiplexing to allow

oth-ers that are being moved onto the same

communica-tions path to be inserted Cells may also be queued

to allow time for the system to insert control cells of

one sort or another See cell rate

cell error ratio In ATM networks, the ratio of cells

in a transmission that are errored to the total cells in

the transmission, over a specified time interval,

pref-erably as measured on an in-service circuit See cell

loss ratio, cell rate

cell interarrival variation CIY In ATM networks,

a description of changes in arrival times of cells

near-ing the receiver If the cells are carrynear-ing information

in which the arrival of the cells at the same time is

important to the synchronization of the final output,

as in constant bit rate (CBR) traffic, then latency and

other delays that cause interarrival variation can

in-terfere with the output For example, in

videoconfer-encing, synchronization of images and sound might

be affected by cell delays See cell rate, cell delay

variation tolerance, jitter

cell loss priority field CLP In ATM networks, a bit

field contained in the header cell that indicates the

cell discard eligibility of the cell In congested

situa-tions, this cell may be expendable

cell loss ratio CLR.InATM networks, cell trafficis

handled in many ways in order to maximize through-put, to synchronize arrival times where appropriate, and to minimize delays, latency,jitter, or loss The cell loss ratio is a negotiated quality ofservice (QoS) param-eter that depends upon the network traffic flow con-trol setups It is computed as a ratio of lost cells to the number of total cells transmitted, expressed as an order of magnitude See cell error ratio, cell loss pri-ority field, cell rate, leaky bucket

cell misinsertion rate CMR In AIM networking, a traffic flow evaluation parameter giving the ratio of cells that are received at the endpoint, that were not originally transmitted by the source, compared to the total number of cells correctly transmitted

cell phone See cellular phone

cell rate In ATM networks, a concept that expresses the flow of basic units of transport used to convey data, signals, and priorities See the Cell Rate Con-cepts chart for further detail See leaky bucket, cell rate margin

cell rate margin CRM In ATM networks, an expres-sion of the difference between the effective band-width allocation for the transmission and the sustain-able cell rate allocation in cells per second

cell relay A type of fast packet switching network architecture using small fixed length packets that can

be used for a variety of data types The cell format is typically 53 octets comprised of 5 bytes of address information and 48 bytes of informational data Cell relays can also provide quality ofservice (QoS) guar-antees to a variety of services See Frame Relay cell relay function In ATM networking, a basic ser-vice provided to ATM endstations See cell relay cell relay service CRS.AnATM carrier service cell reversal In a battery, a reversal ofthe polarity of the terminal cells resulting from discharge

cell site In cellular wireless communications systems,

an individual transceiving unit Multiple cell sites pro-vide roaming capabilities The cell site serves the lo-cal cell and slightly overlaps with adjoining cells to minimize dead spaces between transmissions when

a subscriber passes from one cell region to another cell site controller Cellular radio operates with nu-merous cells, each associated with a transceiver The cell site controller manages the various radio chan-nels within that cell, allocating them when a user moves into range of the cell, and deallocating and re-using available frequencies as the user moves out of range again, or terminates the connection

cell splitting A means of increasing the call capacity ofa cellular system by splitting cells into smaller units cell switch router CSR A network routing device that incorporates ATM cell switching in addition to conventionalLP datagram forwarding, in order to pro-vide improved service over traditional hop-by-hop datagram forwarding, especially with transmissions that pass through subnetwork boundaries See RFC 2098

cell switching In cellular mobile phone systems, the overall process of handling calls, monitoring signals

as users move in and out of range of the transceivers

frequencies as needed to provide seamless service

through a series of cells Cells are designed to

over-lap somewhat so that there is no gap when switching

from one to another and to compensate for the fact

that the signal is weakest on the periphery ofthe

trans-mitting area The sophisticated moment-by-moment

monitoring and orchestrating of this process is

handled by monitoring systems and cell-switching

software

cell transferIn cellular mobile phone systems, the

logistics ofkeeping an ongoing connection at

accept-able volume and quality levels when switching the

user from the transceiver in one cell to the transceiver

ofthe cell that is being entered This transfer involves

allocating a frequency channel in the entered cell and

deallocating and reassigning, ifneeded, the frequency

channel of the exited cell

cell transfer delayCTD In ATM networking, the

time elapsed between a cell exit event at the first point

of measurement and the corresponding cell entry

ticular connection The cell transfer delay between the two points ofmeasurement is the sum ofthe total inter-ATM node transmission delay and the total ATM node processing delay See cell rate

CelloAgraphical Web browser created at the Cornell Legal Information Institute

cellphoneSee cellular phone

cells in flightCIF In ATM networking, a descrip-tive phrase for a traffic service parameter, the avail-able bit rate (ABR) CIF is a cell number limit nego-tiated between the receiving network and the source ofthe cells during the idle startup period, prior to the fIrst RM-cell returns See cell rate, Cells in Frames Cells in FramesCIF The name given to a number

of mechanisms for carrying ATM network traffic across a media segment and network interface card CIF was developed by the Cells in Frames Alliance,

a diverse group ofprofessionals and commercial ven-dors This group released the fIrst CIFsp~cification

in 1996 for carrying ATM over Ethernet, Token-Ring,

Cell Rate Concepts in ATM Networks Abbreviation/Function Descriptor Notes

ACR allowed cell rate A traffic management parameter dynamically managed by

congestion control mechanisms ACR varies between the minimum cell rate (MCR) and the peak cell rate (PCR)

CCR current cell rate Aids in the calculation of ER and may not be changed by the

network elements (NEs) CCR is set by the source to the available cell rate (ACR) when generating a forward RM-cell COP cutoff decrease factor Controls the decrease in the allowed cell rate (ACR)

associated with the cell rate margin (CRM)

CN cell interarrival variation Changes in arrival times of cells nearing the receiver If the

cells are carrying information that must be synchronized, as in constant bit rate (CBR) traffic, then latency and other delays that cause interarrival variation can interfere with the output GCRA generic cell rate algorithm A conformance enforcing algorithm that evaluates arriving

cells See leaky bucket

ICR initial cell rate A traffic flow available bit rate (ABR) service parameter The

ICR is the rate at which the source should be sending the data MCR minimum cell rate Available bit rate (ABR) service traffic descriptor The MCR

is the transmission rate in cells per second at which the source may always send

PCR peak cell rate The PCR is the transmission rate in cells per second that may

never be exceeded, which characterizes the constant bit rate (CBR)

RDF rate decrease factor An available bit rate (ABR) flow control service parameter

that controls the decrease in the transmission rate of cells when it is needed See cell rate

SCR sustainable cell rate The upper measure of a computed average rate of cell

transmission over time

UBR unspecified bit rate Anunguaranteed service type in which the network makes a

best efforts attempt to meet bandwidth requirements

VBR variable bit rate The type of irregular traffic generated by most nonvoice

media Guaranteed sufficient bandwidth and QoS