Fiber Optics Illustrated Dictionary - Part 24 ppt

Filtering may be available for limiting services ISDN Channel Functions BRI Basic Rate Interface 16 kilobytes/second using DSSI to control the two B channels and/or theX.25format user da

Fiber Optics Illustrated Dictionary

cables; since the signal is a lightwave rather than an

electrical signal, the tenn might not seem to apply

However, two types ofproblems related to crosstalk

are characteristic ofoptical systems in the real world,

where installation and structural considerations come

into play:

Some optical systems are hybrid, with

electri-cal links or switches as part ofthe transmission

system, in which case traditional crosstalk at the

electrical interfaces may occur

Inoptical systems where many small fiber

com-ponents are tightly bundled, creating numerous

bends or connective joints, a number of types

of light signal leakage are possible where there

are breaks or weak points in the cladding,

im-proper joints, or misalignments in the endfaces

enabling light signals from one waveguide to

interfere with another, resulting in optical

cross-talk

Optical crosstalk can be minimized by good coupling

and cladding practices and the reduction ofreflection

around joints and bends.Interms of reducing

elec-trical crosstalk at joints, many finns are developing

and installing all-optical switching systems and

link-ing components

CRSSee cell relay service

CRTSee cathode-ray tube

CRTCSee Canadian Radio Television and

Telecom-munications Commission

cryptanalysisThe research and analysis of

crypto-graphy, that is, message or data encryption While

cryptanalysis is generally the art and science of a

broad range ofcypher-related concepts, it is also more

narrowly understood as the actual analysis and

break-ing ofa cyphered message without foreknowledge of

its content, structure, or any keys that might be needed

to discern its contents

cryptocbannelAcommunications channel that is

en-crypted in some way to provide privacy and security

to the conversants When carried out through a

com-puter network, a digitally encrypted mobile

commu-nications line, or a digital telephone line, many means

can be used to hide the signal or the contents of the

signal These include key encryption, scrambling,

fre-quency hopping, and others Cryptochannels were not

generally available to the public before digitally

en-crypted data communications were introduced to

con-sumers in the late 1980s and 1990s; they were mainly

used in government communications, particularly in

the military Now that encryption and secure

chan-nels are becoming available to almost everyone, it

may change the way society communicates

cryptographic ignition keyCIK A token for

stor-ing, transportstor-ing, and protecting cryptographic keys

A cryptographic module and a cryptographic ignition

key may be used together to regenerate a

key-encrypt-ing key

cryptographic keyAninput parameter used in key

encryption security mechanisms to influence the

transformation ofinformation into secured data

gen-erated by a cryptographic algorithm.Ingeneral,

cryp-tographic keys are intended to transform the data into

a uniquely scrambled sequence that cannot be readily interpreted or transformed back into the original mes-sage without the appropriate key information The correct corresponding key may be used to decrypt the message by an authorized recipient This mechanism

is important for securing computer data While there are variations in the level ofsecurity depending upon how the key encryption is implemented, in general the longer the key, the more secure the data in terms

of how technically difficult or time-consuming it would be to try to decrypt the message without the key

Over the years, encryption keys have been getting longer and longer because key encryption aficiona-dos keep finding ways to break the encryption algo-rithms, aided, in part, by more powerful computers and by multiple participants using their computer systems together to accomplish the task Neverthe-less, the cryptographic key model is one of the more secure, better understood, and accepted methods of securing data and is incorporated into various pub-lic/private key systems and digital certificate systems See certification, encryption

cryptographyThe process and study of concealing the contents of a message or transmission from all except the intended recipient It is the primary means ofsecurity in telecommunications The development

of digital communications (ISDN, digital cellular, etc.) makes it easier to provide security, as typical un-scrambled raw data or broadcast signals can be in-tercepted by unauthorized viewers See certificate, Clipper Chip, cryptochannel, encryption, PGP CryptokiA cryptographic token interface in a pub-lic key cryptographic system It defines a crypto-graphic applications programming interface for de-veloping devices to hold cryptographic information and perform cryptographic functions

CryptolopeA type of electronic cryptographic con-tainer for the secure packaging ofdigital information, introduced in 1996 by International Business Ma-chines (IBM) A Cryptolope is a public/private key encryption specification that provides a means to package and distribute control information and con-tent in one package The control infonnation includes pricing, licensing, and conditions of usage Also in-cluded are network addresses and usage data distri-bution instructions Cryptolopes are implemented through Web browser plugins

The Cryptolope package is organized in data layers, including a bill of materials (BOM) describing con-tainer contents; a clear text abstract of the contents, author, etc.; the encrypted contents; intellectual prop-erty rights,related copyrights, and usage rights, etc crystal1 A substance characterized by a repeating internal structure occurring during the solidification

of an element or mixture The characteristic repeat-ing structure is often manifested in the outward appearance Many crystalline forms are transparent

or nearly so See piezoelectricity 2 Apiece oftrans-parent, or semitransparent quartz, usually colorless See quartz 3.Acrystalline material used in electronics

frequency evaluation See crystal detector 4

Awave-sensitive semiconductor used in electronics for

ap-plications such as radar detection

crystal detectorAnelegantly simple, early fonn of

radio device that superseded the coherer Acrystal

de-tector took advantage of the rectifying properties of

various natural and synthetic substances, commonly

galena and carborundum These materials have a

property of allowing electrical alternating current

impulses to pass through in one direction only Thus,

they can be used to convert AC frequencies to a

di-rect current (DC)half-wave.AM radio signals are

converted from radio frequencies to audio

frequen-cies which are audible through headphones or

speakers

Historically, crystal detectors could be built on a very

small scale and could be used without power sources

or amplification, when carefully tuned and connected

with high impedance headphones In essence, they

were the first portable radios and were popular for

field and hobbyist uses

The earliest sets used natural crystals, but later a

num-ber of synthetic crystals were developed, with

vari-ous properties and degrees of sensitivity Portability

could be increased with sets that used crystals that

could be tightly coupled with the catwhisker Some

ofthe more elaborate sets included tuning coils

Even-tually crystal sets were superseded by vacuum tube

radios, which provided amplification and a much

higher degree ofelectronic manipulation and control

Crystal radio sets are still sold as hobby kits from

electronics suppliers, many ofwhom are on the Web

See catwhisker; coherer; Pickard, GreenleafWhittier;

piezoelectric

crystal microphoneAnearly type of microphone

employing a piezoelectric crystal

crystal pickupA particular type of stylus on an

in-strument such as a phonograph, created from a

piezo-electric crystalline material that changes in shape and

consequently generates an electrical impulse which

is then interpreted by the electronics into sound

crystal shutterA type of safety mechanism used in

conjunction with crystal detectors to block excess

radio frequency (RF) energy from reaching and

pos-sibly damaging the components

CScommunications satellite

CSA1 Callpath Services Architecture.2.Canadian

Space Agency The CSA David Florida Laboratory

is particularly known for its research into

telecom-munications technologies 3 See Canadian Standards

Association 4 Center for the Study ofArchitecture/

Archaeology Anorganization devoted to the

ad-vancement of digital technologies suitable for the

study of archaeology and architectural history

http://www.csanet.org/5.client-server architecture

6 communication system architecture 7

Communi-cations Simulator and Analyser A South African

commercial product ofC2J2 that functions as a generic

interactive communications simulator and analyzer

The system supports many different protocols and

media, including Ethernet and some of the newer

ture A 1997 to 1999 EPSRC-funded project for de-signing, constructing, and evaluating a generic sys-tems architecture compliant with individual persis-tent process applications 9 See Comprehensive Sys-tem Accounting 10 computer sysSys-tem architecture

Historic Crystal Radio Wave Detectors r.

This diagram ofa crystal detector, a historic radio receiver, clearly shows the catwhisker and mounting base for the crystal with which the catwhisker is nor-mally in contact, with screws to hold the crystal in place The mounting posts on the left arefor connect-ing the wiresfor the headphones The large knob pro-vides fine adjustment (tuning) for the catwhisker.

This portable crystal detector, with its tuning coil receiver wound around a hollow core, is from the American Radio Museum collection.

esccustomer service center

CSESee Communication Security Establishment

CSISee Computer Security Institute

CSMASee Carrier Sense Multiple Access

CSNETSee Computer+Science Network

CSPPSee Computer Systems Policy Project

CSR 1 See cell switch router.2.customer service record

CST1 See Computer Science Telecommunications

2.computer-supported telephony

CSTASee Computer SupportedTelephonyApplication

CSUSee Channel Service Unit

Fiber Optics Illustrated Dictionary

CSUIDSUChannel Service Unit/Data Service Unit

CSUASee Canadian Satellite Users Association

CT1 Call Type 2 Cordless Telephone 3

Confonn-ance Test Atest to detennine whether an

implemen-tation complies with the specifications of, and

exhib-its behaviors mandated by, a particular standard

CT Innovation AllianceCTIA Anonprofit trade

or-ganization ofcomputer telephony developers and

sys-tems integrators, founded in March 1999 The

Alli-ance was established by the Quebec Ministry of

In-dustry and Commerce to position the province of

Quebec as a center with global scope for computer

telephony research and development R&D areas

in-clude call accounting, voice and facsimile over

In-ternet Protocol (IP), speech recognition, unified

mes-saging, and others http://www.ctinnovation.net/

CT3IPChannelized T3 Interface Processor ACisco

Systems commercial fixed-configuration interface

processor used with Cisco 7xxxseries routers The

CT3IP provides 28 TI channels for serial

transmis-sion of data, each withnx56 kbps ornx64 kbps

bandwidth Unused bandwidth is filled with idle

channel data The CT3IP does not support multiple

T1 channel aggregation (bonding)

CTCASee Canadian Telecommunications

Consult-ants Association

CTDI See cell transfer delay 2 Conditionally Toll

Denied 3 conductivity, temperature, and depth

Elec-tronic devices that measure these variables are used

in water sampling.4.Continuity Tone Detector

CTII Call Technologies, Inc 2 See Computer

Te-lephony Integration 3 See Critical Technologies

In-stitute

CTIA1 See Cellular Telecommunications Industry

Association 2 Computer Technology Industry

As-sociation

CTLSee Complex Text Layout

CTS1 See clear to send See RS-232 2

Communi-cation Transport System 3 Conformance Testing

Services

CTSSCompatible Time-Sharing System

Adevelop-mental computer time-sharing system from the early

1960s

CTTCcoax to the curb Coaxial cable installed into

residential areas See fiber to the home

CTXSee Centrex

CU-SeeMeA Macintosh- and IBM-licensed

PC-based videoconferencing program from Cornell

Uni-versity.Itsupports video, audio, and other utilities

over Internet, with plans to make it

Mbone-compat-ible The encoding is proprietary See Cameo Personal

Video System, Connect 918, MacMICA, IRIS,

ShareView 3000, VISIT Video

cube1 In geometry, a three-dimensional structure

with six equally sized flat square planes all

intercon-nected with each edge in full contact with an edge of

each of the adjacent planes Thus, the point at which

the edges join fonns a comer from which the cube

may be referenced along three mutually

perpendicu-lar axes A cubic structure may be real or imaginary

and does not necessarily specify the size of the

com-ponent planes, which may be infinite 2.colloq.An

early model ofNeXT computer that was shaped like

a black cube, essentially a tower model, for easy ac-cess and upgrade The shape of the NeXT later went

to a more conventional thin slab, which could sit un-der the monitor

cubicEmbodying the geometric structure of a cube

in one or more of its aspects The simplest structure

in a crystal is cubic, with atoms uniformly spaced along three mutually perpendicular axes Aregularly cubic crystalline structure is one that is isotropic, with the atoms spaced equidistant along each axis In tenns ofthe index ofrefraction ofa dieletric material, most solids used in the optics industry are isotropic in any given plane (e.g., glass) However, it is possible to fabricate materials that are anisotropic (varying in density or composition) in order to control their re-fractive properties See cube

CUGclosed (telephone) user group (e.g., as in ISDN Q.85 and Q.735 community of interest services) cure~t.To process so that the essential properties of

a substance are changed, usually to improve them,

as in curing a metal to give it strength or resilience,

or curing a hide to preserve it

curieA unit used for describing the strength of ra-dioactivity, which is equal to 3.7x 1010 disintegra-tions per second It is named after Nobel scientists Pierre and Marie Curie, who did substantial pioneer work in radiation

Curie point, Curie temperatureA temperature at which peak levels of a dielectric constant occur in ferroelectric materials

current(symb - I) Movement of electrons through

a conducting medium, usually expressed in amperes Electricity moving through a wire or cable is current See ampere

current amplifierAny natural, mechanical, or tronic device that provides greater output of an elec-trical signal than the input signal A public address system (PA) is a type ofcurrent amplifier, as are other microphone and speaker combinations

current cell rateCCR In ATM networking, a traf-fic flow control concept that aids in the calculation

of ER and may not be changed by the network ele-ments (NEs) CCR is set by the source to the avail-able cell rate (ACR) when generating a forward RM-cell See cell rate for a chart of related concepts curing ovenA specialized heating device used in fi-ber optics cable assembly to cure bonding agents (e.g., epoxy) faster than by air drying, for example customer access line chargeCALC The charge for connecting a private branch phone exchange (PBX)

to the central office exchange (Centrex)

Customer Owned And MaintainedCOAM.This designation is often used to describe customer-owned telephone devices, for example (a designation that be-came more important when the phone company no longer owned and controlled the phones within a customer's premises)

customer record information systemCRIS Also known in the general sense as CIS, customer infor-mation system, it is a computerized database for tracking customer contact, credit, and purchase

have become so sophisticated, they can generate

re-ports on customer buying frequency, purchase

amounts, family relations, and much more, which

concerns those wish to protect personal privacy

Stores that offer member cards for discounts are

usu-ally the ones tracking customer habits Customers

often have no input into how the information is used,

with whom it is shared, how long it is kept on file, or

which employees have access to the information

cutoff decrease factor CDF In ATM networking,

CDP controls the decrease in the allowed cell rate

(ACR) associated with the cell rate margin (CRM)

cutover That moment when a system is switched

from one to another, as from an old system to a new

one or from a primary system to a backup

A cutover may occur ifa system fails and has

redun-dant resources in place to take over for the primary

system Aring-based network cuts over to a

second-ary ring, for example A power system outage may

cause a cutover to a backup generator

It is usually desirable for the cutover to happen as

quickly and uneventfully as possible, preferably so

users on the system don't even notice the change or

are only momentarily inconvenienced See half tap

cutter A mechanism for inscribing grooves in a

re-cording medium such as a phonographic record The

mechanism is used to translate electrical impulses into

physical patterns that can later be read and converted

back into electrical pulses, usually auditory

CW See Call Waiting

CWIS See Campus Wide Information System

CWSI CiscoWorks for Switched Internetworks

In-tegrated management control technology (for

net-work topology, device configuration, traffic

report-ing, VLAN, ATM, and policy-based management)

from Cisco Systems, Inc

cyber- A prefix widely used with almost anything

these days to indicate an electronic version of

some-thing William Gibson is credited with popularizing

the word "cyberspace" to describe an interconnected

science fiction environment inNeuromancerin 1984

Cyber- and sometimes just cyb- have since been used

in many contexts from computers to music, as in

cy-brarian, cyberceleb, cyberphile, cyberspace,

Cyber-space, cybercast, cyberphant, cyberphobe, etc

cybernetics A term introduced by American prodigy

logician and mathematician, Norbert Wiener, who

collaborated with Arturo Rosenblueth and a group of

scientists from various disciplines in developing

many fundamental concepts ofartificial intelligence

He authoredCybernetics: Or Control and

Commu-nication in the Animal and the Machinein 1948 to

discuss ideas about self-reproducing machines and

self-organizing systems Cybernetics refers generally

to the field ofcontrol and communications theory,

en-compassing both human and nonhuman systems

Wiener further described feedback theory in

math-ematical terms and studied the flow of information

from a statistical point ofview These disciplines have

many practical applications in robotics

InCybernetics,Wiener poses some provocative (and

states and electrical states ofabinaty computing device cyberspace 1 Aterm popularized by William Gibson

in his popular science fiction/fantasy novel

Neuromancerto describe a society in which the par-ticipants live in an abstracted reality, a "consensual hallucination experienced daily by billions " See Cyberspace 2 A content-rich virtual reality environ-ment in which participants interact through a variety

of sensory data input devices

Cyberspace A conceptualization of the computing machinery and its associated culture as an intellec-tually and culturally habitable abstract space exist-ing beyond the obvious physical role of tools and communications devices It has been described as a meta-environment in which we can interact as part ofa larger, perhaps not fully knowable, dynamic, digi-tal organism The Internet is seen as an important component or organizing feature ofthis environment See cyberspace; Dyson, George

Cyberspace Electronic Security Act of1999 CESA

An act of the u.s government that acknowledges fundamental changes in our society stemming from the development of the information superhighway and establishes a middle ground intended to enable law enforcement officials to carry out their duties while safeguarding individual freedoms and rights CESA describes the increasing demand for computer-provided information services and states that new risks arise as a result of their use It contends that

"Cryptography can meet these needs [as] an im-portant tool in protecting the confidentiality of wire and electronic communications and stored data " but that encryption can also " facilitate and hide unlawful activity." The text ofthe Act expresses con-cerns that the normal tools of law enforcement for search and seizure are " wholly insufficient when encryption is utilized to scramble the information in such a manner that law enforcement, acting pursu-ant to lawful authority, cannot decipher the evidence." With respect to the tools oflaw enforcement and their relationship to the pace oftechnology, the Act asserts that "Technology does not presently exist that allows law enforcement to decrypt such information "

In light of the strong encryption technologies that have been developedinthe u.S and abroad, there is evidence to support this last statement, especially given time constraints in particular instances such as terrorist activities

In terms of individual freedoms and privacy, CESA states, "While means to aid investigators' and pros-ecutors' efforts to obtain plaintext are needed, the Act

is not intended to make it unlawful for any person to use encryption in the United States for otherwise lawful purposes, regardless of the encryption algo-rithm selected, key length chosen, or implementation technique or medium used Similarly this Act is not intended to require anyone to use third parties for stor-age of decryption keys, and this Act does not estab-lish any regulatory regime for entities engaging in such an activity Finally, this Act is not intended to affect export controls on cryptographic products."

Fiber Optics Illustrated Dictionary

These last statements are significant because they

represent a departure from the tone and direction of

previous proposals They were included in large part

because ofcriticism and debate between law

enforce-ment supporters on the one hand and civil liberties

supporters and vendors (who desire to compete in the

global marketplace with strongly encrypted products)

on the other

It is an important Act and, due to space limitations,

cannot be wholly included here, but the reader is

en-couraged to look up the CESA text and become

fa-miliar with its tenets and implications See

Ameri-can Civil Liberties Union, Electronic Communications

Privacy Act of 1986, Electronic Frontier Foundation,

Electronic Privacy Infonnation Center

CyberStar Acommercial global satellite

communi-cations system designed to provide broadband,

inter-active multimedia data transmissions CyberStar is a

venture of lora1Space & Communications

Cyber-Star operates on leased Ku-band transponders on the

Telstar system

CyberTelecom See Washington Internet Project

cybrarian A compound word derived from

cyber{space] and librarian A cybrarian is a

librar-ian/research professional setting up resources or

con-ducting research and information retrieval online,

es-pecially on the Internet Given the astounding

vol-ume offree infonnation on the Net, and the difficulty

of narrowing the search and finding relevant

infor-mation, in essence locating the needle in the haystack,

cybrarians provide valuable information, filtering,

and organizational services You can find almost any

type ofinfonnation on the Web, from people's names

and addresses, to scientific abstracts and more, and

this could easily be a full-time occupation

cyclic fatigue Fatigue in a material from prolonged,

repetitive, low-level vibration

Glass and glass-like plastics suitable for fiber optic

lightguides and ceramic ferrules in fiber optic

con-nectors may become brittle and subject to breakage

from overt stresses but are not considered highly

vul-nerable to cyclic fatigue in nonnal installations

Tests for oyclic fatigue in optic fiber have been

con-ducted using high-resolution micromechanical

meth-ods Various types ofmatrix strains, fiber strains, and

crack opening displacements (CaDs) were detected

by researchers in the mid-1990s Rousseau et a1

de-termined that the debonding of fibers "begins at the

point of matrix cracking and rapidly increases."

So, while cyclic fatigue is not significant in fiber

op-tics overall, slight existing cracks introduced from

coupling stresses, installation strain, excessive

bend-ing, etc., could be exacerbated by the additional stress

of cyclic fatigue Also, the materials supporting

fi-ber optics structures may be subject to cyclic fatigue,

even if the inner core is reasonably resistant to

re-petitive forces, so it is still a factor to be considered

in cable installation

Incables in general, possible sources ofcyclic fatigue

include road traffic vibrations, wind on aerial cables,

vibrations from construction machinery, etc

cyclic memory Atype ofmemory that can be accessed only when the process of memory access passes through that portion in its cycle that contains the in-fonnation desired

cyclic olefm polymer (COP) A synthetic material used to coat silver hollow glass lightguides suitable for the conduction oflaser-emitted infrared radiation

Ithas good heat resistance, transparency and electri-cal characteristics The material is marketed under a number of names by different companies, including ZEON's ZEONIX, Mitsui Chemicals' Apel, and oth-ers In Summer 200I,Goodrich Corporation, a ma-jor developer of the material, sold its Electronic Ma-terials Division to Sumitomo Bakelite Co., Ltd cyclic redundancy check CRC A file integrity and data transmission error checking mechanism widely used in computing The CRC is a calculate-and-com-pare system A block of data, the total data content ofa file, or a group oftransferred data can be scanned

to create a numeric sum total that provides a simple representation ofits contents This total is then com-pared with one that is computed in the same way af-ter file compression, manipulation, or transfer The computed values are evaluated If they match, an

er-ror may have occurred, but with a low probability of

likelihood Ifthey don't match, an error is likely, and the data transfer or manipulation may be repeated File transfer programs such as ZModem often in-cluded CRC methods to monitor data transfer Some file compression formats, such as PNG, are divided into logical data chunks, with each chunk incorpo-rating a CRe to provide a reference for data integ-rity so the file can be checked without opening the image in a viewer See checksum, magic signature cyclic shift A system in which anything that comes out one end of the production line, register, stack, or other physical or logical conveyance goes back in at the beginning ofthe system in a continuous loop Pro-grammers sometimes use cyclic shifts to rearrange data

cyclotron A device for devising nuclear manipula-tions that follow a helical path There are many makes and models ofcyclotrons, ranging also greatly in size

Acommon, basic configuration is an evacuated con-tained space in which charged atomic particles are guided and accelerated through a spiral path by vari-ous magnetic means The centripetal path ofthe par-ticles can be used to effect radiant emissions cypherpunkAnindividual advocating the preven-tion oftyranny through public access and widespread dissemination ofelectronic cyphers, encryption meth-ods, and other digital security technologies, in order

to ensure that their power and accessibility are not concentrated in the hands of only a few people or or-ganizations See Pretty Good Privacy; Zimmennann, Philip

Czochralski technique Ameans ofcreating crystal-line structures that are useful in semiconductor tech-nologies By passing the materials throughAmolten state, large single crystals can be grown Drawing crystals from a melt is known as "crystal pulling."

in mathematics to symbolize a difference in or change

of/in For example, a=L\v would be interpreted as

acceleration equals a change in velocity.

d symb -deci-, a prefix used to denote one tenth, or

10-1,as in decimeter, deCibel.

D 1 symb dual polarization (ITU) 2 symb

electro-static flux density See flux

D bank, digital bank, digital channel bankIn data

communications, a multiplexer combining analog

signals from a number oflow-rate data channels into

a single high-rate digital signal at the transmitter or

converting digital to analog at the receiving end

D banks are commonly used in time-division

multi-plexing (TOM) In North American pulse-code

modulation (PCM) systems, 24 channels are

com-bined through TDM for transmission over a single

line operating at DSI rates See D channel, time

di-vision multiplexing See DS- for a fuller explanation

and a chart

D bitIn anX.25network, the D bit is a binary

indi-cator at the beginning of a data packet, immediately

following theQbit, that signals successful packet

delivery Following theQand D bits are a number of

protocol fields including the piggyback and sequence

fields used for flow control The D bit indicates the

meaning of the data in the piggyback field If D is

set to zero (0), the local data communications

equip-ment (DCE) received the packet but it isn't indicated

whether the remote data terminal equipment (DTE)

received the packet IfD is set to one (1), it indicates

that the remote data terminal equipment (DTE) has

received the packet SeeQbit

(FCC) designation for a Personal Communications Services (PCS) license granted to a telephone com-pany serving a Major Trading Area (MTA) This li-cense grants permission to operate in a 10-Mhz block

at certain FCC-specified frequencies See ABlock for

a chart of frequencies

D channel delta channel, data channel A channel used for managing network connections The D chan-nel is the administrative chanchan-nel for ISDN with Sig-naling System 7 (SS7).InISDN, the D channel is a full-duplex channel that carries control and signal-ing information It handles various call setup and teardown functions (e.g., establishment and handling ofB channels) and signals subscriber service infor-mation such as Caller ID The D (delta) channel con-trols the B (bearer) channel at 16,000 bps for Basic Rate Interface (BRI) or 64,000 bps for Primary Rate Interface (PRI) as shown in the ISDN Channel Func-tions chart One D channel is typically associated with two or more B channels

The D channel utilizes three layers and associated protocols for implementing communications (Note that there are some differences in Layer 3 D channel implementations between North American and Eu-ropean versions of ISDN.)

D channel software monitors will generally show D channel statistics in terms offrames sent and received along with a number of diagnostic and error codes including overruns, timeouts, residue, buffer status, call attempts, etc Buffering may be available for ana-lyzing D channel characteristics remotely or at a later time Filtering may be available for limiting services

ISDN Channel Functions

BRI Basic Rate Interface 16 kilobytes/second using DSSI to control the two B

channels and/or theX.25format user data.

PRI Primary Rate Interface 64 kilobytes/second using DSSI to control all the B

channels In conjunction with NFAS, the D channel can also control B channels on multiple PRISe

Fiber Optics Illustrated Dictionary

or for detecting and preventing unauthorized

manipu-lation of D channel communications Depending

upon the product, the monitoring software may be

linked into the system at the terminal (T) interface to

monitor both forward and backward signal paths

In Link Access Procedure (LAP), the recommended

protocol for a circuit-switched network, the D

chan-nel carries the signaling information See B chanchan-nel,

D bank, D channel stack, ISDN, protocol analyzer,

QSeries Recommendations

D channel stack In ISDN, a signaling stack that

pro-vides access to the resources of the D channel at the

SITreference point The stack implements the three

lower layers of the OSI reference model Vendors

such as Texas Instruments have developed D

chan-nel stack products as self-contained firmware

de-signed to cooperate with the host-based Common

ISDN API (CAPI) See D Channel

D connector A standard cable connector that is

housed in a shell that resembles the letter D The

elon-gated D-shape is a naturally keyed shape as the curved

edges on one side provide a guide to the correct

ori-entation for connecting the cable D connectors,

es-pecially 9-, 15-, and 25-pin are commonly used to

interconnect computers and peripheral devices such

as printers, monitors, and modems Most AlB

switch-boxes for computer data connections use DB-25

in-puts and outin-puts See DB-25

D link In Signaling System 7 (SS7) networks, the D

link is a diagonal link that connects a secondary

Sig-nal Transfer Point (STP) pair to a primary STP pair

in a quad-link configuration Thus, a local STP pair

may be linked to a network gateway STP pair

Some-times calledBID links since B links (bridge links) are

a more generic designation for interconnecting STPs

D region A region (as opposed to a layer) of the

Earth's ionosphere that exists only in the daytime,

starting from around 70 or 80 kilometers above the

Earth's surface and extending up to and overlapping

the E region, which is more clearly defined The D

region can have a significant impact on the

propaga-tion of radio waves, causing greater dissipapropaga-tion and

attenuation when the region is active in the daytime

See ionospheric sublayers for a chart

D Series RecommendationsA series of

recom-mended guidelines for general telecommunications

tariff principles that may be purchased from the

ITU-T Since ITU-T specifications and

recommen-dations are widely followed by vendors in the

tele-communications industry, those wanting to maximize

interoperability with other systems should be aware

of the information disseminated by the lTU-T Afull

list of general categories is in the Appendix and

spe-cific series topics are listed under individual entries

in this dictionary, e.g., B Series Recommendations,

C Series Recommendations, etc See ITU-T D Series

Reconnnendationschart

D- conditioningAs specified by the lTU for D-l and

D-2 transmission lines, a means to handle 9.6 Kbps

operations by improving the signal-to-noise ratio and

nonlinear (harmonic) distortion to within certain

specified limits For example, for D-l conditioning,

the SIN ratio parameter may be defmed by a vendor

as 28 decibels with the signal-to-modulation ratio parameters defined as 35 or 40 decibels, depending upon the order of the intermodulation distortion D-conditioning varies with the type of service being offered over the D channel that is being conditioned Not all conditioning is suitable for all types of ser-vices For example, a D-conditioned line may not be optimal for voice communications

D-l, D-2, D-3, etc See digital video format for a chart

of standardized formats

D-scope, D-scanA type of C-scope radar display in which the target blips extend vertically to provide an estimate of distance See C-scope

D-VHS Adigital version ofVHS recording/playback technology developed byNC.Since digital technolo-gies are so easily transmitted to or from computer applications and over Internet links, formats like D-VHS may become important for Web-based commu-nications Digital variants are also important in video editing as no data is lost in the editing asinanalog formats Many digital video technologies are transi-tional They use digital imaging but often store the information on tapes rather than disks or magnetic cards They may also play older format analog tapes See SVHS

DAMPS, D-AMPS Digital Advanced Mobile Phone Service Descended from AMPS, DAMPS was intro-duced as a 900MHzfrequency modulation (FM) sec-ond-generation mobile phone transmission technol-ogy in the early 1990s DAMPS was capable of car-rying three digital channels, compared to one analog AMPS channel, in a 3D-kHz analog slot Modulation

is through a 2-bits-per-symbol nonbinary modem

In DAMPS, bandwidth is allocated according to fre-quency division multiple access (FDMA) schemes The two most prevalent means of dividing frequen-cies in DAMPS are time division multiple access (TDMA) and code division multiple access (CDMA)

To increase capacity and security in mobile commu-nications, in general, many cellular systems are be-ing converted from AMPS to digital AMPS (DAMPS) Some legacy systems supporting AMPS, which is based upon frequency division multiple ac-cess (FDMA), have a dual mode for selecting mul-tiple access (the formats are not directly compatible) See AMPS, North American Digital Cellular D'Arsonval, Jacques Arsene(1851-194D)AFrench physicist who proposed using the thermal properties

of the ocean to generate energy He was unable to achieve a net gain in power generation Succeeding generations of researchers continued to pursue this idea with better success through experimentation D'Arsonval introduced the first reflecting, moving coil galvanometer in 1882, an improvement on pre-vious arrangements By means of a small, concave mirror mounted on the coil, the instrument could re-flect a beam oflight to a calibrated scale It could mea-sure the current and voltage ofdirect currents and was widely distributed in many forms Anumber ofelec-trical concepts and inventions are named after him See galvanometer, D'Arsonval

Tenns and definitions for the Series-D Recommendations

General principles for the lease of international (continental _a.l ].(.,=ljnten:on1ttt1~~ntalU· private telecommunication circuits and networks

Principles for the lease of analog international circuits for private service

Special conditions for the lease of international (continental' and intercontinental) sound- and television-program circuits for private service

Costs and value of services rendered as factorsinthe fixing of rates

Concept and implementation of "one-stop shopping" for international' prlvateleased telecommunication circuits

Special conditions for the leaseofintemationalend-to-enddigitalcircl.litsforprivate

Private leasingoftransmittersOfreceivers

General tariff prirtciples·for intertlationalpublicdatacdInmunicationseMces

Specialtariffprinciples for international packet-switched publicdatacommunication servicesby means of the virtual callfacility

Measurement unit for charging by volumein the international packet-switched data communication service

Guiding principles to govern the apportionment of accounting mtesinintemational packet-switched publicdatacommunication relations

General charging and accounting principles for nonvoice· services provided.by

interworking between publicdatanetworks

Special tarifTprinciples for the international circuit-switched publicdata

communication services

Special tariff principles for short transaction transmissions onthe international packet-switched public data networks usingthefastsel~ctfacilitywitb.restrictiol1

Implementation of reverse charging on international publicdatacommunication

services

General charging principlesinthe international public message handling services and associated applications

General accounting principles applicable to message handling services and associated applications

Accounting and settlement principles applicable to the provisionafpublic directory services between interconnected Directory Management'Domains

General tariff principles applicabletotelegrams exchanged in the' international public telegram service

Introduction of accounting ratesbyzones in the intemationalpuolictClegrattfseMce Accounting in theintemational~ublic~legramservic~ , ' > / < i < '

Partial and total refund ofchargesin tbeintemationalpublic telegraniisetvice

Charging and accounting principles, for the international telemessage service

Tariff and international accounting principles for the international teletexservice Guiding principles to govern the apportionment of accounting ratesinintercontinental telex relations

Charging and accounting provisions relatingtothe measurement ofthechargeable duration of a telex call

General charging and accounting principles in the international telex service for multi-address messages via store-and-forward units

Charging and accounting inthe.international telex service

General tariff principles for the 'international public facsimileiserviee'between public bureaus (bureaufax service)

generaltariffprinciples.forthepublicfa.csimil~.service.betwe~!l sU1:J~Cribel"sUltions

Number

D.OOO

DJ

D.3

D.4

D.5

D.7

0.8

D.9

D.lO

DJl

D.l2

0.13

DJ5

D.20

D.21

0.30

D.35

0.36

D.37

0.40

D.41

D.42

D.43

0.45

0.50

D.60

0.61

D.65

D.67

D.70

D.71

Description

Fiber Optics Illustrated Dictionary

Number

. lTU-T D Series Recommendations, coot•

Description D.73

D.79

D.80

D.81

0.83

D.85

D.90

D.91

0.93

D.94

D.95

D.96

D.98

D.100

D.I03

D.104

D.105

D.106

D.lIO

D.lls

D.116

0.117

D.120

D.l40

D.150

D.1S1

D.ISS

D.160

D.170

0.171

D.172

D.173

D.174

General tariff and intemlltionalaccounting principles for interworking between the : intemationalbureaufaxandtelefax services

Charging'and accounting principles for the international videotex service Accounting and refunds: for phototelegrams

Accounting and refunds for private phototelegraph calls Rates for phototelegrams and privatephototelegraph caUs Charging for international phototelegraph calls to multiple destinations Charging, billing, international accounting and settlement in the maritime mobile service

Transmission in encodedform of maritime telecommunications accounting ' information

Charging and accounting in thc:intemationallandmobiletelephone~ervice(provided via cellular radio systems)

Charging,billing, and accounting principlesJor international aeronalltical mobile service and international aeronautical mobile-satellite service

Charging, billing, accounting, and refunds in the data messaging land/maritime mobile-satellite service

Charging, billing, accounting, and settlement principles for Global Mobile Personal Communications by Satellite(GMPCS)forthe international telephone service Charging and accounting provisions relatingtothe transferred account telegraph and telematic services

Charging for international calls in manual or semi-automatic operating Charginginautomatic service for calls terminating on a recorded announcement

Chargingforcallsto<subscriber'ssUlfion ·connected eithertotheabsentsuhscriber's serviceortoa device' substituting a Sllbscriberinhis.absence

Charging for calls from orto a,publiccalloffice Introduction of reduced rates during periods of light traffic in intemationaltelephone service

Charging and accounting for conference calls Tariffprinciples and accounting for the International Freephone Service (IFS) Charging and accounting principles relatingtothe home country direct telephone service

Charging and accounting principles for the international premium rate service (IPRS) Charging and accounting principles for thejnternational telecommunication charge card service

Accounting •.rateprinciples.•forintet'Il!ltionaltelephone servicea New system for accounting in international telephony Old•• srste111.foraccountit,lg in intel1uqional~elephony

Guiding principles governing the apportionment of accounting rates in intercontinental telephone relations

Mode<of application of the flat-rate price procedure set forth in Recommendation D.67 and RecommendationD.150for remuneration of facilities made availabletothe administrations of other countries

Monthly telephone and telex accounts Adjustments and refunds in the international telephone service Accounting for calls circulated over intemational routes for which accounting rates have not been established

Defaulting subscribers Conventional transmission ofinformation necessary for billing and accounting regarding collect and credit card calls

0.176

0.177

0.178

0.180

0.185

0.186

D.188

0.190

0.192

0.193

0.196

0.197

0.201

0.210

0.211

0.212

0.220

0.224

D.22S

0.230

0.231

D.232

0.233

0.240

D.250

0.251

D.260

0.280

0.285

0.286

0.300R

Description

Transmission in encoded fonn of telephone reversed charge biJlingandaccounting

information

Adjustment of charges and refundsinthe international telex service

Monthly accounts for semi-automatic telephone calls (ordinaryand urgentcalls,with

or without special facilities)

Occasional provision of circuitsforinternational sound-andtelevision-program

transmissions

Generaltariffand accounting principles for international one-way point-to-multipoint

satellite services

Geneml tariff and accounting principles for international two-way multipoint

telecommunicationservice viasatellite

General· charging and accounting principles11pplicable to an international

videoconferencingservice • •·•• ··.i » i · i ••

Exchange of international traffic accollntingdata among administrations using

electronic data interchange(E01)techniques

Principles for charging and accounting of service telecommunicationS

Special tariff principles for privilege telecommunications

Clearing of international telecommunication balances of accounts

Notification of change of address(es) for accounting and settlementpurposes

General principles regarding call-back practices

Generalcharging and accounting principles for international telecomtnooication

services provided over the Integrated Services Digital Network (ISDN)

International accounting for the use o.fthe signaltransferpoi~tandlor~igna~lingpoint

forrelay inSignalling System No.7 ••• ··>i •• <> •••. •••• i < /.i

Charging and accounting principlesforthe useofSignalling.Systenl~o.7

Charging ·and·accounting •principles to·be appliedto··internationalcircttit-moae· •

demand bearer services provided.over the Integrated Services DigitalNetwork (ISDN)

Charging and accounting principles forATMIB-ISDN

Charging and accounting principlestobeapplied to frame relaydata.transmission

service

General charging and accounting principles for supplementary services associated

with international telecommunication.services provided overthe.Integrated Services

Digital Network (ISDN)

Charging and accounting principles relating to the User-to-User Infonnation{UUI)

supplementary service

~pecifictariffand accounting principlesapplicable toISDNslJJ:lPlem~~taryservices

Charging and accounting principlestoneapplied to the reversed charge

supplementary service i / ..i i< > ••• •·••• /i .<.

Charging and accounting principles forteleservices supported tiytheJSON

General charging and accounting principles for nonvoice services provided by

interworkingbetween the ISDN and existing public data networks

General charging and accounting principles for the basic telephone service provided

over the ISDN or by interconnection between the ISDN and the public switcbed

telephone network

Charging and accounting capabilities to be applied on the ISDN

Principles for charging and billing, accounting and reimbursements for universal

personal telecommunication

Guiding principles for charging and accounting for inteJligentnetworksuppOrted

Chargingandaccounting principles for theglobar"irtualIletwOrksetVice

Detennination ofaccounting rate shares in telephone relationsamongcoU111:ries in

EUropeand the Mediterranean Basin

•.I f R I , r • •.~ ,