Abbreviations and Acronyms

C c centi (10-2) CACS centralized alarm control system CAM computer-aided manufacturing CAMA centralized automatic message accounting CAN cancel character CAP competitive access provider; customer administration panel CARS cable television relay service [station] CAS centralized attendant services CASE computer-aided software engineering; computer aided system engi-

neering; computer-assisted software engineering CATV cable TV; cable television; community antenna television CBX computer branch exchange C2 command and control C3 command, control, and communications C3CM C3 countermeasures C3I command, control, communications and intelligence CCA carrier-controlled approach CCD charge-coupled device CCH connections per circuit hour CCIF International Telephone Consultative Committee CCIR International Radio Consultative Committee CCIS common-channel interoffice signaling CCIT International Telegraph Consultative Committee CCITT International Telegraph and Telephone Consultative Committee CCL continuous communications link CCS hundred call-seconds CCSA common control switching arrangement CCTV closed-circuit television CCW cable cutoff wavelength cd candela CD collision detection; compact disk CDF combined distribution frame; cumulative distribution function CDMA code-division multiple access CDPSK coherent differential phase-shift keying CDR call detail recording CD ROM compact disk read-only memory CDT control data terminal CDU central display unit C-E communications-electronics CEI comparably efficient interconnection CELP code-excited linear prediction CEP circular error probable CFE contractor-furnished equipment

cgs centimeter-gram-second ChR channel reliability CIAS circuit inventory and analysis system CIC content indicator code CIF common intermediate format CIFAX ciphered facsimile CiR circuit reliability C/kT carrier-to-receiver noise density CLASS custom local area signaling service cm centimeter CMI coded mark inversion CMIP Common Management Information Protocol CMIS common management information service CMOS complementary metal oxide substrate CMRR common-mode rejection ratio CNR carrier-to-noise ratio; combat-net radio CNS complementary network service C.O. central office COAM customer owned and maintained equipment COBOL common business oriented language codec coder-decoder COG centralized ordering group COMINT communications intelligence COMJAM communications jamming compandor compressor-expander COMPUSEC computer security COMSAT Communications Satellite Corporation COMSEC communications security CONEX connectivity exchange CONUS Continental United States COP Committee of Principals COR Council of Representatives COT customer office terminal CPAS cellular priority access services CPE customer premises equipment cpi characters per inch cpm counts per minute cps characters per second CPU central processing unit; communications processor unit CR channel reliability; circuit reliability CRC cyclic redundancy check CRITICOM Critical Intelligence Communications CROM control read-only memory CRT cathode ray tube c/s cycles per second CSA Canadian Standards Association CSC circuit-switching center; common signaling channel CSMA carrier sense multiple access

CSMA/CA carrier sense multiple access with collision avoidance CSMA/CD carrier sense multiple access with collision detection CSU channel service unit; circuit switching unit; customer service unit CTS clear to send CTX Centrex® [service]; clear to transmit CVD chemical vapor deposition CVSD continuously variable slope delta [modulation] cw carrier wave; composite wave; continuous wave CX composite signaling cxr carrier

D d deci (10-1) da deka (10) D-A digital-to-analog; digital-to-analog converter D/L downlink DACS digital access and cross-connect system DAMA demand assignment multiple access DARPA Defense Advanced Research Projects Agency dB decibel dBa decibels adjusted dBa0 noise power measured at zero transmission level point dBc dB relative to carrier power dBm dB referred to 1 milliwatt dBm(psoph) noise power in dBm measured by a set with psophometric weighting DBMS database management system dBmV dB referred to 1 millivolt across 75 ohms dBm0 noise power in dBm referred to or measured at 0TLP dBm0p noise power in dBm0 measured by a psophometric or noise measur-

ing set having psophometric weighting dBr power difference in dB between any point and a reference point dBrn dB above reference noise dBrnC noise power in dBrn measured by a set with C-message weighting dBrnC0 noise power in dBrnC referred to or measured at 0TLP dBrn(f1-f2) flat noise power in dBrn dBrn(144) noise power in dBrn measured by a set with 144-line weighting dBv dB relative to 1 V (volt) peak-to-peak dBW dB referred to 1 W (watt) dBx dB above reference coupling dc direct current DCA Defense Communications Agency DCE data circuit-terminating equipment DCL direct communications link DCPSK differentially coherent phase-shift keying DCS Defense Communications System DCTN Defense Commercial Telecommunications Network DCWV direct-current working volts DDD direct distance dialing

DDN Defense Data Network DDS digital data service DEL delete character demarc demarcation point demux demultiplex; demultiplexer; demultiplexing dequeue double-ended queue DES Data Encryption Standard detem detector/emitter DFSK double-frequency shift keying DIA Defense Intelligence Agency DID direct inward dialing DIN Deutsches Institut für Normung DIP dual in-line package DISA Defense Information Systems Agency DISC disconnect command DISN Defense Information System Network DISNET Defense Integrated Secure Network DLA Defense Logistic Agency DLC digital loop carrier DLE data link escape character DM delta modulation DMA Defense Mapping Agency; direct memory access DME distance measuring equipment DMS Defense Message System DNA Defense Nuclear Agency DNIC data network identification code DNPA data numbering plan area DNS Domain Name System DO design objective DoC Department of Commerce DOD Department of Defense; direct outward dialing DODD Department of Defense Directive DODISS Department of Defense Index of Specifications and Standards DOD-STD Department of Defense Standard DOS Department of State DPCM differential pulse-code modulation DPSK differential phase-shift keying DQDB distributed-queue dual-bus [network] DRAM dynamic random access memory DRSI destination station routing indicator DS digital signal; direct support DS0 digital signal 0 DS1 digital signal 1 DS1C digital signal 1C DS2 digital signal 2 DS3 digital signal 3 DS4 digital signal 4 DSA dial service assistance

DSB double sideband (transmission); Defense Science Board DSB-RC double-sideband reduced carrier transmission DSB-SC double-sideband suppressed-carrier transmission DSC digital selective calling DSCS Defense Satellite Communications System DSE data switching exchange DSI digital speech interpolation DSL digital subscriber line DSN Defense Switched Network DSR data signaling rate DSS direct station selection DSSCS Defense Special Service Communications System DSTE data subscriber terminal equipment DSU data service unit DTE data terminal equipment DTG date-time group DTMF dual-tone multifrequency (signaling) DTN data transmission network DTS Diplomatic Telecommunications Service DTU data transfer unit; data tape unit; digital transmission unit; direct to

user DVL direct voice link DX signaling direct current signaling; duplex signaling

E E exa (1018) E-MAIL electronic mail EAS extended area service EBCDIC extended binary coded decimal interchange code Eb/N0 signal energy per bit per hertz of thermal noise EBO embedded base organization EBS Emergency Broadcast System EBX electronic branch exchange EC Earth coverage; Earth curvature ECC electronically controlled coupling; enhance call completion ECCM electronic counter-countermeasures ECM electronic countermeasures EDC error detection and correction EDI electronic data interchange EDTV extended-definition television EHF extremely high frequency EIA Electronic Industries Association eirp effective isotropically radiated power; equivalent isotopically radi-

ated power EIS Emergency Information System el elevation ELF extremely low frequency ELINT electronics intelligence; electromagnetic intelligence

ELSEC electronics security ELT emergency locator transmitter EMC electromagnetic compatibility EMCON emission control EMD equilibrium mode distribution EME electromagnetic environment emf electromotive force EMI electromagnetic interference; electromagnetic interference control EMP electromagnetic pulse EMR electromagnetic radiation EMR hazards electromagnetic radiation hazards e.m.r.p. effective monopole radiated power; equivalent monopole radiated

power EMS electronic message system EMSEC emanations security emu electromagnetic unit EMV electromagnetic vulnerability EMW electromagnetic warfare; electromagnetic wave ENQ enquiry character EO end office E.O. Executive Order EOD end of data EOF end of file EOL end of line EOM end of message EOP end of program; end output EOS end-of-selection character EOT end-of-transmission character; end of tape EOW engineering orderwire EPROM erasable programmable read-only memory EPSCS enhanced private switched communications system ERL echo return loss ERLINK emergency response link ERP, e.r.p. effective radiated power ES end system; expert system ESC escape character; enhanced satellite capability ESF extended superframe ESM electronic warfare support measures ESP enhanced service provider ESS electronic switching system ETB end-of-transmission-block character ETX end-of-text character EW electronic warfare EXCSA Exchange Carriers Standards Association

F f femto (10-15) f frequency

FAA Federal Aviation Administration FAQ file Frequently Asked Questions file FAX facsimile FC functional component FCC Federal Communications Commission FCS frame check sequence FDDI fiber distributed data interface FDDI-2 fiber distributed data interface-2 FDHM full duration at half maximum FDM frequency-division multiplexing FDMA frequency-division multiple access FDX full duplex FEC forward error correction FECC Federal Emergency Communications Coordinators FED-STD Federal Standard FEMA Federal Emergency Management Agency FEP front-end processor FET field effect transistor FIFO first-in first-out FIP Federal Information Processing FIPS Federal Information Processing Standards FIR finite impulse response FIRMR Federal Information Resources Management Regulations FISINT foreign instrumentation signals intelligence flops floating-point operations per second FM frequency modulation FO fiber optics FOC final operational capability; full operational capability FOT frequency of optimum traffic; frequency of optimum transmission FPIS forward propagation ionospheric scatter fps foot-pound-second FPS frames per second; focus projection and scanning FRP Federal Response Plan FSDPSK filtered symmetric differential phase-shift keying FSK frequency-shift keying FSS fully separate subsidiary FT fiber optic T-carrier FTAM file transfer, access, and management FTF Federal Telecommunications Fund ft/min feet per minute FTP file transfer protocol ft/s feet per second FTS Federal Telecommunications System FTS2000 Federal Telecommunications System 2000 FTSC Federal Telecommunications Standards Committee FWHM full width at half maximum FX fixed service; foreign exchange service FYDP Five Year Defense Plan

G g profile parameter G giga (109) GBH group busy hour GCT Greenwich Civil Time GDF group distribution frame GETS Government Emergency Telecommunications Service GFE Government-furnished equipment GGCL government-to-government communications link GHz gigahertz GII Global Information Infrastructure GMT Greenwich Mean Time GOS grade of service GOSIP Government Open Systems Interconnection Profile GSA General Services Administration GSTN general switched telephone network G/T antenna gain-to-noise-temperature GTP Government Telecommunications Program GTS Government Telecommunications System GUI graphical user interface

H h hecto (102); hour; Planck’s constant HCS hard clad silica (fiber) HDLC high-level data link control HDTV high-definition television HDX half-duplex (operation) HE11 mode the fundamental hybrid mode (of an optical fiber) HEMP high-altitude electromagnetic pulse HERF hazards of electromagnetic radiation to fuel HERO hazards of electromagnetic radiation to ordnance HERP hazards of electromagnetic radiation to personnel HF high frequency HFDF high-frequency distribution frame HLL high-level language HPC high probability of completion HV high voltage Hz hertz

I IA International Alphabet I&C installation and checkout IC integrated circuit ICI incoming call identification ICNI Integrated Communications, Navigation, and Identification ICW interrupted continuous wave IDDD International Direct Distance Dialing IDF intermediate distribution frame

IDN integrated digital network IDTV improved-definition television IEC International Electrotechnical Commission IEEE Institute of Electrical and Electronics Engineers IES Industry Executive Subcommittee IF intermediate frequency I/F interface IFF identification, friend or foe IFRB International Frequency Registration Board IFS ionospheric forward scatter IIR infinite impulse response IITF Information Infrastructure Task Force ILD injection laser diode ILS instrument landing system IM intensity modulation; intermodulation I&M installation and maintenance IMD intermodulation distortion IMP interface message processor IN intelligent network INFOSEC information systems security INS inertial navigation system INTELSAT International Telecommunications Satellite Consortium INWATS Inward Wide-Area Telephone Service I/O input/output (device) IOC integrated optical circuit; initial operational capability; input-output

controller IP Internet protocol; intelligent peripheral IPA intermediate power amplifier IPC information processing center IPM impulses per minute; interference prediction model; internal polar-

ization modulation; interruptions per minute in/s inches per second ips interruptions per second IPX Internet Packet Exchange IQF intrinsic quality factor IR infrared IRAC Interdepartment Radio Advisory Committee IRC international record carrier; Interagency Radio Committee ISB independent-sideband (transmission) ISDN Integrated Services Digital Network ISM industrial, scientific, and medical (applications) ISO International Organization for Standardization ITA International Telegraph Alphabet ITA-5 International Telegraph Alphabet Number 5 ITC International Teletraffic Congress ITS Institute for Telecommunication Sciences ITSO International Telecommunications Satellite Organization ITU International Telecommunication Union

IVDT integrated voice data terminal IXC interexchange carrier

J JANAP Joint Army-Navy-Air Force Publication(s) JCS Joint Chiefs of Staff JPL Jet Propulsion Laboratory JSC Joint Steering Committee; Joint Spectrum Center JTC3A Joint Tactical Command, Control and Communications Agency JTIDS Joint Tactical Information Distribution System JTRB Joint Telecommunications Resources Board JTSSG Joint Telecommunications Standards Steering Group JWID Joint Warrior Interoperability Demonstration

K k kilo (103); Boltzmann’s constant K coefficient of absorption; kelvin KDC key distribution center KDR keyboard data recorder KDT keyboard display terminal kg kilogram kg·m·s kilogram-meter-second kHz kilohertz km kilometer kΩ, k kilohm KSR keyboard send/receive device kT noise power density KTS key telephone system KTU key telephone unit

L LAN local area network LAP-B Data Link Layer protocol (CCITT Recommendation X.25 [1989]) LAP-D link access procedure D laser light amplification by stimulated emission of radiation LASINT laser intelligence LATA local access and transport area LBO line buildout LC limited capability LCD liquid crystal display LD long distance LDM limited distance modem LEC local exchange carrier LED light-emitting diode LF low frequency LFB look-ahead-for-busy (information) LIFO last-in first-out LLC logical link control (sublayer)

l/m lines per minute LMF language media format LMR land mobile radio LNA launch numerical aperture LOF lowest operating frequency loran long-range aid to navigation system; long-range radio navigation;

long-range radio aid to navigation system LOS line of sight, loss of signal LP linearly polarized (mode); linear programming; linking protection;

log-periodic (antenna); log-periodic (array) LPA linear power amplifier LPC linear predictive coding LPD low probability of detection LPI low probability of interception lpi lines per inch lpm lines per minute LP01 the fundamental mode (of an optical fiber) LQA link quality analysis LRC longitudinal redundancy check LSB lower sideband, least significant bit LSI large scale integrated (circuit); large scale integration; line status in-

dication LTC line traffic coordinator LUF lowest usable high frequency LULT line-unit-line termination LUNT line-unit-network termination LV low voltage

M m meter M mega (106) MAC medium access control [sublayer] MACOM major command MAN metropolitan area network MAP manufacturers’ automation protocol maser microwave amplification by the stimulated emission of radiation MAU medium access unit MCC maintenance control circuit MCEB Military Communications-Electronics Board MCM multicarrier modulation MCS Master Control System MCW modulated continuous wave MCXO microcomputer compensated crystal oscillator MDF main distribution frame MDT mean downtime MEECN Minimum Essential Emergency Communications Network MERCAST merchant-ship broadcast system MF medium frequency; multifrequency (signaling)

MFD mode field diameter MFJ Modification of Final Judgment MFSK multiple frequency-shift keying MHF medium high frequency MHS message handling service; message handling system MHz megahertz mi mile MIC medium interface connector; microphone; microwave integrated cir-

cuit; minimum ignition current; monolithic integrated circuit; mutual interface chart

MILNET military network MIL-STD Military Standard min minute MIP medium interface point MIPS, mips million instructions per second MIS management information system MKS meter-kilogram-second MLPP multilevel precedence and preemption MMW millimeter wave modem modulator-demodulator mol mole ms millisecond (10-3 second) MSB most significant bit MSK minimum-shift keying MTBF mean time between failures MTBM mean time between maintenance MTBO mean time between outages MTBPM mean time between preventive maintenance MTF modulation transfer function MTSO mobile telephone switching office MTSR mean time to service restoration MTTR mean time to repair µ micro (10-6) µs microsecond MUF maximum usable frequency MUX multiplex; multiplexer MUXing multiplexing mw microwave MWI message waiting indicator MWV maximum working voltage

N n nano (10-9); refractive index N0 sea level refractivity; spectral noise density NA numerical aperture NACSEM National Communications Security Emanation Memorandum NACSIM National Communications Security Information Memorandum NAK negative-acknowledge character

NASA National Aeronautics and Space Administration NATA North American Telecommunications Association NATO North Atlantic Treaty Organization NAVSTAR Navigational Satellite Timing and Ranging NBFM narrowband frequency modulation NBH network busy hour NBRVF narrowband radio voice frequency NBS National Bureau of Standards NBSV narrowband secure voice NCA National Command Authorities NCC National Coordinating Center for Telecommunications NCS National Communications System; net control station NCSC National Communications Security Committee NDCS network data control system NDER National Defense Executive Reserve NEACP National Emergency Airborne Command Post NEC National Electric Code® NEP noise equivalent power NES noise equivalent signal NF noise figure NFS Network File System NIC network interface card NICS NATO Integrated Communications System NID network interface device; network inward dialing; network informa-

tion database NII National Information Infrastructure NIOD network inward/outward dialing NIST National Institute of Standards and Technology NIU network interface unit NLP National Level Program nm nanometer NMCS National Military Command System nmi nautical mile NOD network outward dialing Np neper NPA numbering plan area NPR noise power ratio NRI net radio interface NRM network resource manager NRRC Nuclear Risk Reduction Center NRZ non-return-to-zero NRZI non-return-to-zero inverted NRZ-M non-return-to-zero mark NRZ-S non-return-to-zero space NRZ1 non-return-to-zero, change on ones NRZ-1 non-return-to-zero mark ns nanosecond NSA National Security Agency

NSC National Security Council NS/EP National Security or Emergency Preparedness telecommunications NSTAC National Security Telecommunications Advisory Committee NTCN National Telecommunications Coordinating Network NTDS Naval Tactical Data System NT1 Network termination 1 NT2 Network termination 2 NTI network terminating interface NTIA National Telecommunications and Information Administration NTMS National Telecommunications Management Structure NTN network terminal number NTSC National Television Standards Committee; National Television Stan-

dards Committee (standard) NUL null character NVIS near vertical incidence skywave

O O&M operations and maintenance OC operations center OCC other common carrier OCR optical character reader; optical character recognition OCU orderwire control unit OCVCXO oven controlled-voltage controlled crystal oscillator OCXO oven controlled crystal oscillator OD optical density; outside diameter OFC optical fiber, conductive OFCP optical fiber, conductive, plenum OFCR optical fiber, conductive, riser OFN optical fiber, nonconductive OFNP optical fiber, nonconductive, plenum OFNR optical fiber, nonconductive, riser OMB Office of Management and Budget ONA open network architecture opm operations per minute OPMODEL operations model OPSEC operations security OPX off-premises extension OR off-route service; off-route aeronautical mobile service OSHA Occupational Safety and Health Administration OSI open switching interval; Open Systems Interconnection OSI-RM Open Systems Interconnection-Reference Model OSRI originating stations routing indicator OSSN originating stations serial number OTAM over-the-air management of automated HF network nodes OTAR over-the-air rekeying OTDR optical time domain reflectometer; optical time domain reflectometry OW orderwire [circuit]

P p pico (10) P peta (1015) PABX private automatic branch exchange PAD packet assembler/disassembler PAL phase alternation by line PAL-M phase alternation by line-modified PAM pulse-amplitude modulation PAMA pulse-address multiple access p/a r peak-to-average ratio PAR performance analysis and review PARAMP parametric amplifier par meter peak-to-average ratio meter PAX private automatic exchange PBER pseudo-bit-error-ratio PBX private branch exchange PC carrier power (of a radio transmitter); personal computer PCB power circuit breaker; printed circuit board PCM pulse-code modulation; plug compatible module; process control

module PCS Personal Communications Services; personal communications sys-

tem; plastic-clad silica (fiber) PCSR parallel channels signaling rate PD photodetector PDM pulse delta modulation; pulse-duration modulation PDN public data network PDS protected distribution system; power distribution system; program

data source PDT programmable data terminal PDU protocol data unit PE phase-encoded (recording) PEP peak envelope power (of a radio transmitter) pF picofarad PF power factor PFM pulse-frequency modulation PI protection interval PIC plastic insulated cable ping packet Internet groper PIV peak inverse voltage PLA programmable logic array PL/I programming language 1 PLL phase-locked loop PLN private line network PLR pulse link repeater PLS physical signaling sublayer pm phase modulation PM mean power; polarization-maintaining (optical fiber); preventive

maintenance; pulse modulation

PMB pilot-make-busy (circuit) PMO program management office POI point of interface POP point of presence POSIX portable operating system interface for computer environments POTS plain old telephone service PP polarization-preserving (optical fiber) P-P peak-to-peak (value) P/P point-to-point PPM pulse-position modulation pps pulses per second PR pulse rate PRF pulse-repetition frequency PRI primary rate interface PRM pulse-rate modulation PROM programmable read-only memory PRR pulse repetition rate PRSL primary area switch locator PS permanent signal psi pounds (force) per square inch PSK phase-shift keying PSN public switched network p-static precipitation static PSTN public switched telephone network PTF patch and test facility PTM pulse-time modulation PTT postal, telephone, and telegraph; push-to-talk (operation) PTTC paper tape transmission code PTTI precise time and time interval PU power unit PUC public utility commission; public utilities commission PVC permanent virtual circuit; polyvinyl chloride (insulation) pW picowatt PWM pulse-width modulation PX private exchange

Q QA quality assurance QAM quadrature amplitude modulation QC quality control QCIF quarter common intermediate format QMR qualitative material requirement QOS quality of service QPSK quadrature phase-shift keying QRC quick reaction capability

R racon radar beacon

rad radian; radiation absorbed dose radar radio detection and ranging RADHAZ electromagnetic radiation hazards RADINT radar intelligence RAM random access memory; reliability, availability, and maintainability R&D research and development RATT radio teletypewriter system RBOC Regional Bell Operating Company RbXO rubidium-crystal oscillator RC reflection coefficient; resource controller RCC radio common carrier RCVR receiver RDF radio-direction finding REA Rural Electrification Administration REN ringer equivalency number RF radio frequency; range finder RFI radio frequency interference RFP request for proposal RFQ request for quotation RGB red-green-blue RH relative humidity RHR radio horizon range RI routing indicator RISC reduced instruction set chip RJ registered jack RJE remote job entry rms root-mean-square (deviation) RO read only; receive only ROA recognized operating agency ROC required operational capability ROM read-only memory ROSE remote operations service element protocol rpm revolutions per minute RPM rate per minute RPOA recognized private operating agency rps revolutions per second RQ repeat-request RR repetition rate RSL received signal level rss root-sum-square R/T real time RTA remote trunk arrangement RTS request to send RTTY radio teletypewriter RTU remote terminal unit RTX request to transmit RVA reactive volt-ampere RVWG Reliability and Vulnerability Working Group

RWI radio and wire integration RX receive; receiver RZ return-to-zero

S s second SCC specialized common carrier SCE service creation environment SCF service control facility SCP service control point SCPC single channel per carrier SCR semiconductor-controlled rectifier; silicon-controlled rectifier SCSR single channel signaling rate SDLC synchronous data link control SDM space-division multiplexing SDN software-defined network SECDEF Secretary of Defense SECORD secure voice cord board SECTEL secure telephone SETAMS systems engineering, technical assistance, and management services SEVAS Secure Voice Access System S-F store-and-forward SF single-frequency (signaling) SGDF supergroup distribution frame S/H sample and hold SHA sidereal hour angle SHARES Shared Resources (SHARES) HF Radio Program SHF super high frequency SI International System of Units SID sudden ionospheric disturbance SIGINT signals intelligence SINAD signal-plus-noise-plus-distortion to noise-plus-distortion ratio SLD superluminescent diode SLI service logic interpreter SLP service logic program SMDR station message-detail recording SMSA standard metropolitan statistical area SNR signal-to-noise ratio SOH start-of-heading character SOM start of message sonar sound navigation and ranging SONET synchronous optical network SOP standard operating procedure SOR start of record SOW statement of work (S+N)/N signal-plus-noise-to-noise ratio sr steradian S/R send and receive

SSB single-sideband (transmission) SSB-SC single-sideband suppressed carrier (transmission) SSN station serial number SSP service switching point SSUPS solid-state uninterruptible power system STALO stabilized local oscillator STD subscriber trunk dialing STFS standard time and frequency signal (service); standard time and fre-

quency service STL standard telegraph level; studio-to-transmitter link STP standard temperature and pressure; signal transfer point STU secure telephone unit STX start-of-text character SUB substitute character SWR standing wave ratio SX simplex signaling SXS step-by-step switching system SYN synchronous idle character SYSGEN system generation

T T tera (1012) TADIL tactical data information link TADIL-A tactical data information link-A TADIL-B tactical data information link-B TADS teletypewriter automatic dispatch system TADSS Tactical Automatic Digital Switching System TAI International Atomic Time TASI time-assignment speech interpolation TAT trans-Atlantic telecommunication (cable) TC toll center TCB trusted computing base TCC telecommunications center TCCF Tactical Communications Control Facility TCF technical control facility TCP transmission control protocol TCS trusted computer system TCU teletypewriter control unit TCVXO temperature compensated-voltage controlled crystal oscillator TCXO temperature controlled crystal oscillator TD time delay; transmitter distributor TDD Telecommunications Device for the Deaf TDM time-division multiplexing TDMA time-division multiple access TE transverse electric [mode] TED trunk encryption device TEK traffic encryption key TEM transverse electric and magnetic [mode]

TEMPEST compromising emanations TEMS telecommunications management system TGM trunk group multiplexer THD total harmonic distortion THF tremendously high frequency THz terahertz TIA Telecommunications Industry Association TIE time interval error TIFF tag image file format TIP terminal interface processor TK response timer TLP transmission level point TM transverse magnetic [mode] TP toll point TRANSEC transmission security TRC transverse redundancy check TRF tuned radio frequency TRI-TAC tri-services tactical [equipment] TSK transmission security key TSP Telecommunications Service Priority [system] TSPS traffic service position system TSR telecommunications service request; terminate and stay resident TTL transistor-transistor logic TTTN tandem tie trunk network TTY teletypewriter TTY/TDD Telecommunications Device for the Deaf TV television TW traveling wave TWT traveling wave tube TWTA traveling wave tube amplifier TWX® teletypewriter exchange service TX transmit; transmitter

U UDP User Datagram Protocol UHF ultra high frequency U/L uplink ULF ultra low frequency UPS uninterruptible power supply UPT Universal Personal Telecommunications service USB upper sideband USDA U.S. Department of Agriculture USFJ U.S. Forces, Japan USFK U.S. Forces, Korea USNO U.S. Naval observatory USTA U.S. Telephone Association UT Universal Time UTC Coordinated Universal Time

uv ultraviolet

V V volt VA volt-ampere VAN value-added network VAR value added reseller VARISTAR variable resistor vars volt-amperes reactive VC virtual circuit VCO voltage-controlled oscillator VCXO voltage-controlled crystal oscillator V/D voice/data Vdc volts direct current VDU video display unit; visual display unit VF voice frequency VFCT voice frequency carrier telegraph VFDF voice frequency distribution frame VFO variable-frequency oscillator VFTG voice-frequency telegraph VHF very high frequency VLF very low frequency V/m volts per meter VNL via net loss VNLF via net loss factor vocoder voice-coder vodas voice-operated device anti-sing vogad voice-operated gain-adjusting device volcas voice-operated loss control and echo/signaling suppression vox voice-operated relay circuit; voice operated transmit VRC vertical redundancy check VSAT very small aperture terminal VSB vestigial sideband [transmission] VSM vestigial sideband modulation VSWR voltage standing wave ratio VT virtual terminal VTU video teleconferencing unit vu volume unit

W WADS wide area data service WAIS Wide Area Information Servers WAN wide area network WARC World Administrative Radio Conference WATS Wide Area Telecommunications Service; Wide Area Telephone Ser-

vice WAWS Washington Area Wideband System WDM wavelength-division multiplexing

WHSR White House Situation Room WIN WWMCCS Intercomputer Network WITS Washington Integrated Telecommunications System WORM write once, read many times wpm words per minute wps words per second wv working voltage WVDC working voltage direct current WWDSA worldwide digital system architecture WWMCCS Worldwide Military Command and Control System WWW World Wide Web

X XMIT transmit XMSN transmission XMTD transmitted XMTR transmitter XO crystal oscillator XOFF transmitter off XON transmitter on XT crosstalk XTAL crystal

Z Z Zulu time ZD zero defects Zo characteristic impedance 0TLP zero transmission level point