Fiber Optics Illustrated Dictionary - Part 24 ppt

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 of optical 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 of the transmission system, in which case traditional crosstalk at the electrical interfaces may occur. In optical 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- properjoints, 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. In terms of reducing elec- trical crosstalk at joints, many finns are developing and installing all-optical switching systems and link- ing components. CRS See cell relay service. CRT See cathode-ray tube. CRTC See Canadian Radio Television and Telecom- munications Commission. cryptanalysis The research and analysis ofcrypto- graphy, that is, message or data encryption. While cryptanalysis is generally the art and science of a broad range of cypher-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. cryptocbannelA communications 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 key CIK. A token for stor- ing, transporting, and protecting cryptographic keys. A cryptographic module and a cryptographic ignition key may be used together to regenerate a key-encrypt- ing key. cryptographic key An input parameter used in key encryption security mechanisms to influence the transformation ofinformation into secured data gen- erated by a cryptographic algorithm. In general, cryp- 222 tographic keys are intended to transform the data into auniquely 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. cryptography The process and study ofconcealing 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. Cryptoki Acryptographic 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 ofelectronic cryptographic con- tainer for the secure packaging of digital 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. crystal 1. 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. A crystalline material used in electronics © 2003 by CRC Press LLC for various purposes such as timing, rectification, and frequency evaluation. See crystal detector. 4. A wave- sensitive semiconductor used in electronics for ap- plications such as radar detection. crystal detector An elegantly simple, early fonn of radio device that superseded the coherer. A crystal 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 of the more elaborate sets included tuning coils. Even- tually crystal sets were superseded by vacuum tube radios, which provided amplification and a much higher degree of electronic manipulation and control Crystal radio sets are still sold as hobby kits from electronics suppliers, many of whom are on the Web. See catwhisker; coherer; Pickard, Greenleaf Whittier; piezoelectric. crystal microphone An early type of microphone employing apiezoelectric crystal. crystal pickup Aparticular 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. CS communications satellite. CSA 1. 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 of Arc hi tec ture/ Archaeology. An organization 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 of C2J2 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 fiber-based systems. 8. Compliant Systems Architec- ture. A 1997 to 1999 EPSRC- funded project for de- signing, constructing, and evaluating ageneric sys- tems architecture compliant with individual persis- tent process applications. 9. See Comprehensive Sys- tem Accounting. 10. computer system architecture. Historic Crystal Radio Wave Detectors r. This diagram of a 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 mountingposts on the left are for connect- ingthe wires for the headphones. The large knobpro- videsfine 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. esc customer service center. CSE See Communication Security Establishment. CSI See Computer Security Institute. CSMA See Carrier Sense Multiple Access. CSNET See Computer+Science Network. CSPP See Computer Systems Policy Project. CSR 1. See cell switch router. 2. customer service record. CST 1. See Computer Science Telecommunications 2. computer-supported telephony. CSTA See Computer Supported Telephony Application. CSU See Channel Service Unit. 223 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary CSUIDSU Channel Service Unit/Data Service Unit. CSUA See Canadian Satellite Users Association. CT 1. Call Type. 2. Cordless Telephone. 3. Confonn- ance Test. A test to detennine whether an implemen- tation complies with the specifications of, and exhib- its behaviors mandated by, a particular standard. CT InnovationAlliance CTIA. A nonprofit trade or- ganization of computer 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/ CT3IP Channelized T3 Interface Processor. A Cisco Systems commercial fixed-configuration interface processor used with Cisco 7 xxx series routers. The CT3IP provides 28 TI channels for serial transmis- sion of data, each with n x 56 kbps or n x 64 kbps bandwidth. Unused bandwidth is filled with idle channel data. The CT3IP does not support multiple T1 channel aggregation (bonding). CTCA See Canadian Telecommunications Consult- ants Association. CTD I. 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. CTI I. Call Technologies, Inc. 2. See Computer Te- lephony Integration. 3. See Critical Technologies In- stitute. CTIA 1. See Cellular Telecommunications Industry Association. 2. Computer Technology Industry As- sociation. CTL See Complex Text Layout. CTS 1. See clear to send. See RS-232. 2. Communi- cation Transport System. 3. Conformance Testing Services. CTSS Compatible Time-Sharing System. A develop- mental computer time-sharing system from the early 1960s. CTTC coax to the curb. Coaxial cable installed into residential areas. See fiber to the home. CTX See Centrex. CU-SeeMe A Macintosh- and IBM-licensed PC- based videoconferencing program from Cornell Uni- versity. It supports 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, Mac MICA, IRIS, ShareView 3000, VISIT Video. cube 1. 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 224 early model of NeXT 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. cubic Embodying the geometric structure ofa 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. A regularly cubic crystalline structure is one that is isotropic, with the atoms spaced equidistant along each axis. In tenns of the 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. CUG closed (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. curie Aunit used for describing the strength of ra- dioactivity, which is equal to 3.7 x 10 10 disintegra- tions per second. It is named after Nobel scientists Pierre and Marie Curie, who did substantial pioneer work in radiation. Curie point, Curie temperature A 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. currentamplifier Any natural, mechanical, or elec- tronic device that provides greater output of an elec- trical signal than the input signal. A public address system (PA) is a type of current amplifier, as are other microphone and speaker combinations. current cell rate CCR. 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 achart of related concepts. curing oven Aspecialized 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 charge CALC. The charge for connecting a private branch phone exchange (PBX) to the central office exchange (Centrex). Customer Owned And Maintained COAM. 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 system CRIS. Also known in the general sense as CIS, customer infor- mation system, it is a computerized database for tracking customer contact, credit, and purchase © 2003 by CRC Press LLC information. In the last half decade, these systems 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. A ring-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 in Neuromancer in 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. cyberneticsA 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 authored Cybernetics: Or Control and Commu- nication in the Animal and the Machine in 1948 to discuss ideas about self-reproducing machines and self-organizing systems. Cybernetics refers generally to the field of control 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 of view. These disciplines have many practical applications in robotics. In Cybernetics, Wiener poses some provocative (and revolutionary at the time) parallels between neuron states and electrical states ofa binaty computing device. cyberspace 1. A term popularized by William Gibson in his popular science fiction/fantasy novel Neuromancer to 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 avariety 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 of this environment. See cyberspace; Dyson, George. Cyberspace Electronic SecurityAct of 1999 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 of the 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 of law enforcement and their relationship to the pace of technology, 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 developed in the 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 ofdecryption 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." 225 © 2003 by CRC Press LLC 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 of criticism 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. CyberStarA commercial global satellite communi- cations system designed to provide broadband, inter- active multimedia data transmissions. CyberStar is a venture of lora 1 Space & 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 of free 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 of matrix 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. In cables in general, possible sources of cyclic fatigue include road traffic vibrations, wind on aerial cables, vibrations from construction machinery, etc. 226 cyclic memory A type of memory 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 of laser-emitted infrared radiation. It has 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 200 I, 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 of transferred data can be scanned to create a numeric sum total that provides a simple representation of its 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. If they 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 of the 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 of cyclotrons, ranging also greatly in size. A common, 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 of the par- ticles can be used to effect radiant emissions. cypherpunk An individual advocating the preven- tion of tyranny through public access and widespread dissemination of electronic 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 techniqueA means of creating crystal- line structures that are useful in semiconductor tech- nologies. By passing the materials through A molten state, large single crystals can be grown. Drawing crystals from a melt is known as "crystal pulling." © 2003 by CRC Press LLC 0, L\ symb. The third letter of the Greek alphabet, used 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 bank In data communications, a multiplexer combining analog signals from a number of low-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 DS I rates. See D channel, time di- vision multiplexing. See DS- for afuller explanation and a chart. D bit In an X.25 network, the D bit is a binary indi- cator at the beginning ofa data packet, immediately following the Q bit, that signals successful packet delivery. Following the Q and 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. See Q bit. D Block A Federal Communications Commission (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 A Block 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 channel for ISDN with Sig- naling System 7 (SS7). In ISDN, 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 3D channel implementations between North American and Eu- ropean versions of ISDN.) D channel software monitors will generally show D channel statistics in terms of frames sent and received along with a number ofdiagnostic 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 alater time. Filtering may be available for limiting services ISDN Channel Functions Abbreviation Service Notes BRI Basic Rate Interface 16 kilobytes/second using DSSI to control the two B channels and/or the X.25 format 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 227 © 2003 by CRC Press LLC 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 channel, D bank, D channel stack, ISDN, protocol analyzer, Q Series Recommendations. Dchannel stack In ISDN, a signaling stack that pro- vides access to the resources of the D channel at the SIT reference 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 outputs. See DB-25. Dlink 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 called BID 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 dissipation and attenuation when the region is active in the daytime. See ionospheric sub layers for a chart. D Series Recommendations A 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. A full 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- TD Series Reconnnendationschart. D- conditioning As 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, 228 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-scan A type of C-scope radar display in which the target blips extend vertically to provide an estimate of distance. See C-scope. D- VHS A digital version ofVHS recording/playback technology developed by NC. 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 as in analog 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 900 MHz frequency 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, JacquesArsene (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 of light to a calibrated scale. It could mea- sure the current and voltage of direct currents and was widely distributed in many forms. A number of elec- trical concepts and inventions are named after him. See galvanometer, D' Arsonval. © 2003 by CRC Press LLC 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 factors in the fixing of rates Concept and implementation of "one-stop shopping" for international'prlvateleased telecommunication circuits Special conditions for the lease of intemationalend-to-enddigitalcircl.litsforprivate service ' Private leasing of transmitters Of receivers General tariff prirtciples· for intertlationalpublicdatacdInmunicationseMces Special tariffprinciples for internationalpacket-switched public data communication services by means of the virtual callfacility Measurement unit for charging by volume in the international packet-switched data communication service Guiding principles to govern the apportionment of accounting mtes inintemational packet-switched public data communication relations General charging and accounting principles for nonvoice· services provided .by interworking between public data networks Special tarifTprinciples for the international circuit-switched public data communication services Special tariffprinciples for short transaction transmissions on the international packet- switched public data networks using the fast sel~ct facilitywitb.restrictiol1. Implementation of reverse charging on international public data communication services General charging principles in the 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 tariffprinciples applicable to telegrams exchanged in the'international public telegram service Introduction of accounting rates by zones. in the intemationalpuolictClegrattfseMce Accounting in the intemational~ublic~legramservic~ ,'>/<i<' Partial and totalrefund of charges in tbeintemationalpublic telegrani i setvice Charging and accounting principles, for .the international tel emess age service Tariff and international accounting principles for the international teletexservice Guiding principles to govern the apportionment of accounting rates in intercontinental telex relations Charging and accounting provisions relating to the measurement of the chargeable 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 in the. international telex service General tariffprinciples for the 'international. public facsimileiserviee'between public bureaus (bureaufax service) general tariffprinciples.forthepublicfa.csimil~.service.betwe~!l sU1:J~Cribel"sUltions (telefax service) , .,. 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 lTU-T DSeries RecommendatioDs " 229 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Number . lTU-T D Series Recommendations, coot• Description 230 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 Generaltariff 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 inthc:intemationallandmobile telephone~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 refundsin 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 relating to the transferred account telegraph and telematic services Charging for international calls in manual or semi-automatic operating Charging in automatic service for calls terminating on a recorded announcement statin~ the reasonforthecallno~be~~colllpleted Chargingforcallsto<subscriber'ssUlfion ·connected eithertotheabsentsuhscriber's serviceor to a device' substituting a Sllbscriber in his. absence Charging for calls from or to a, public calloffice 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 relating to the home country direct telephone service Charging and accounting principles for the international premium rate service (IPRS) . Charging and accounting principles for thejnternationaltelecommunication 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 Recommendation D.150 for remuneration of facilities made available to the 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 of information necessary for billing. and accounting regarding collect and credit card calls © 2003 by CRC Press LLC Number 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 ITU-T D Series Recommendations, cont. Description Transmission in encoded fonn of telephone reversed charge biJlingandaccounting information Adjustment of charges and refunds in the international telex service Monthly accounts for semi-automatictelephone calls (ordinary and urgent calls, with or without special facilities) Occasional provision of circuits for international sound- and television-program transmissions General tariff and accounting principles for international one-way point-to-multipoint satellite .services Geneml tariff and accounting principles for international two-way multipoint telecommunicationservice via satellite General· charging and accounting principles 11pplicable 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 tariffprinciples 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 signal transferpoi~tandlor~igna~ling point for relay in Signalling System No.7 ••• . . ··>i •• <> •••. • •••. i </ .i Charging and accounting principles for the use ofSignalling.Systenl~o.7 Charging .·and· accounting•principles to·be applied to·· internationalcircttit-moae· • demand bearer services provided.over the Integrated Services DigitalNetwork (ISDN) Charging and accounting principles forATMIB-ISDN Charging and accounting principles to be applied to frame relay data .transmission service General charging and accounting principles for supplementary services associated with international telecommunication.services.provided over the. Integrated Services Digital Network (ISDN) Charging and accounting principles relating to the User-to-UserInfonnation{UUI) supplementary service ~pecific tariffand accountingprinciplesapplicable to ISDNslJJ:lPlem~~taryservices Charging and accounting principles tone applied to the reversed charge supplementary service i / . . .i. . . i< > ••• • · •••. /i .<. Charging and accounting principles forteleservices supportedtiytheJSON 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 services . . Charging and accounting principles fortheglobar"irtualIletwOrksetVice Detennination of accounting rate shares in telephone relationsamongcoU111:ries in EUrope and the MediterraneanBasin 231 •. IfRI,.r .• •. ~ , © 2003 by CRC Press LLC . 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-, 1 5-, 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 outputs. See DB-25. Dlink 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 called BID links since B links (bridge links) are a more generic designation for interconnecting STPs. D. idle channel data. The CT3IP does not support multiple T1 channel aggregation (bonding). CTCA See Canadian Telecommunications Consult- ants Association. CTD I. 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. CTI I. Call Technologies, Inc. 2. See Computer Te- lephony Integration. 3. See Critical Technologies In- stitute. CTIA 1. See Cellular Telecommunications Industry Association. 2. Computer Technology Industry As- sociation. CTL See Complex Text Layout. CTS 1. See clear to send. See RS-232. 2. Communi- cation Transport System. 3. Conformance Testing Services. CTSS Compatible Time-Sharing System. A develop- mental computer time-sharing system from the early 1960s. CTTC coax to the curb. Coaxial cable installed into residential areas. See fiber to the home. CTX See Centrex. CU-SeeMe A Macintosh- and IBM-licensed PC- based videoconferencing program from Cornell Uni- versity. It supports video, audio, and other utilities over Internet, with plans to make it Mbone-compat- ible. The encoding is proprietary. See Cameo Personal Video System,. LLC 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 of criticism 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. CyberStarA commercial global satellite communi- cations system designed to provide broadband, inter- active multimedia data transmissions. CyberStar is a venture of lora 1 Space & Communications. Cyber- Star operates on leased Ku-band transponders on the Telstar system. CyberTelecom See Washington Internet Project. cybrarian