Satellite Technology Glossary

Satellite Technology Glossary

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There are currently 2701 names in this directory
2P-PAP(Two)
Pulse Amplitude and Phase Modulation Modem

3DTV
3DTVThree Dimensional Television

4PDT
Four-Pole Double-Throw

4PST
Four-Pole Single-Throw

A
Ampere

A-h
Amp-House

a.c. OR AC
Acquisition Cycle

a.u.
Astronomical Unit

A/D
Analog to Digital Conversion

AAC
Automatic Amplitude Control

ABC
Automated Brightness Control

ABM
Apogee Booster Motor

ABS
Absent

ABU
Asia-Pacific Broadcasting Union

AC/DC
Alternating Current or Direct Current

ACAST
Advisory Committee on the Application of Science and Technology to Development (UN)

ACC
Administrative Committee on Coordination

ACCEL OR ACEL
Accelerometer

ACD
Automatic Call Distribution

ACDE
Attitude Control and Determination Electronics

ACDS
Attitude Control and Determination Subsystem

ACE
Attitude Control Electronics

ACI
Acknowledgment Signal Unit

ACM
Acceptance Testing & Configuration Management

ACME
Analog Circuit Multiplication Equipment

ACP
Acquisition and Synchronization Processor

ACS
Attitude Control Subsystem

ACSSB
Amplitude Companded Single Sideband

ACTP
Abridged Condensed Time Plan

ACTS
Advanced Communication Technology Satellite (USA)

ACU
Acquisition Control Unit

ADC
Analog to Digital Converter

ADCE
Attitude Determination and Control Equipment

ADCS
Analog Despin Control System

ADDER
Automatic Digital Data Error Recorder

ADDR
Address Complete

ADE
Automatic Design Engineering

ADF
Automatic Direction Finder

ADI
Alternate Digital Conversion

ADM
Adaptive Delta Modulation

ADMA
Administrative Committee on Coordination

ADP
Acquisition Phase UW Detection

ADPCM
Adaptive Differential Pulse Code Modulation

AEN
Equivalent Articulation Loss (USA)

AEROSAT
Aeronautical Satellite System

AF
Audio Frequency

AFC
Automatic Frequency Control

AFCAC
African Civil Aviation Commission

AFSATCOM
Air Force Satellite Communications System (USA)

AFSK
Amplitude and Frequency-Shift Keying

AFT
Automatic Fine Tuning

AGC
Automatic Gain Control

AGRIS
Agricultural Research Information Service (FAO - USA)

Ah
Ampere-Hour

AI
Articulation Index (of a speech circuit)

AIAA
American Institute of Aeronautics and Astronautics (USA)

AIBD
Asia-Pacific Institute for Broadcasting Development

AIRE
Alarm Indication to Remote End

AIS
Alarm Indication Signal

AKM
Apogee Kick Motor

ALC
Automatic Light/Level Control

ALF
Absorption Limiting Frequency

ALGOL
Algorithmic Language

ALM
Apogee Lowering Maneuver

ALOHA
System developed by University of Hawaii to use RMA for Pacific island communications

ALT
Alternate

ALU
Arithmetic Logic Unit

AM
Air Mass

AMA
Automatic Message Accounting

AMC
Assistant Maneuver Coordinator

AMDS
Automated Earth Station Monitor & Diagnostics System

AMF
Apogee Motor Fire/Firing

AMI
Alternate Mark Inversion (signal); (bipolar signal)

AMS
Attitude Measurement Sensor

AMSAT
Radio Amateur Satellite Corporation (USA)

AMSL
Above Mean Sea Level

AMSS
Automatic Message Switching System

AMVFT
Amplitude-Modulated Voice Frequency Telegraphy

ANC
Active/Automatic Nutation Control

ANCS
Active Nutation Control(ler) System

AND
Type of logic circuit

ANDS
Active Nutation Damping System

ANG
Angle

ANI
Automatic Number Identification

ANIK
Domestic satellite network (owned by Telesat - Canada)

ANL
Automatic Noise Limiter

ANOD
Anode

ANS
Astronomical Netherlands Satellite (Netherlands/USA)

ANSI
American National Standards Institute (USA)

ANT
Antenna

ANTEL
Administraci n Nacional de Telecomunicaciones (El Salvador)

ANTELCO
Administraci n Nacional de Telecomunicaciones (Paraguay)

AOCS
Attitude and Orbit Control Subsystem

AOR
Atlantic Ocean Region

AOS
Acquisition of Signal

AP
Access Point

APC
Automatic Phase Control

APCS
Autonomous Payload Control System

APD
Acquisition Phase Unique Word Detection

APE
Antenna Positioning Electronics

API
Application Program Interface

APK
Amplitude-Phase Keying

APKS
Amplitude-Phase-Keyed System

APL
Average Picture Level

APM
Antenna Positioning Mechanism

APR
Asia Pacific Region

APS
Antennal Position Data Select Switch

APT
Asian Pacific Telecommunity

APTU
African Postal and Telecommunications Union

ARA
Angular Rate Assembly

ARABSAT
Arab Satellite Communication Organization

ARAEN
Reference system for the determination of the articulation reference equivalents

ARC
Atlantic Resotration Committee

ARE
Automatic Reconfiguration Electronics

ARENTO
Telecommunications organization (Arab Republic of Egypt)

ARIANE
Commercial European launch vehicle

ARIANESPACE
European Organization which operates ARIANE launch vehicle systems

ARIEL
Ionospheric satellite (UK)

ARM
Armed

ARP
Apparent Radiated Power

ARPA
Advanced Research Projects Agency (USA)

ARQ
Automatic Repeat Request

ARRL
American Radio Relay League (USA)

ART
Additional Reference Carrier Transmission

ARTI
Arab Regional Telecommunications Institute

AS
Articulation Score

ASA
American Standards Association

ASB
Anti-sideband

ASBU
Arab States Broadcasting Union

ASC
American Satellite Company (USA)

ASCII
American National Standard Code for Information Interchange

ASE
Airborne Support Equipment

ASEAN
Association of South East Asian Nations

ASETA
Asociacion de Empresas Estataless de Tellecomunicacion del Acuerdo Subregional Andino (Association of State-owned Telecommunications of Subregional Andean Agreement)

ASI
Asynchronous Serial Interface

ASIASAT
Asian satellite system supported by UK

ASK
Amplitude Shift Keying

ASL
Above Sea Level

ASP
Acquisition and Synchronization Processor

ASR
Automatic Send and Receive

ASSR
Acquisition and Steady State Reception

AST
American Society for Testing Materials

ASTRA
Application of Space Techniques Relating to Aviation

ASU
Acknowledgment Signal Unit

ASWA
Adjustable Solar Wing Actuator

AT
Acceptance Test

AT&T
American Telephone and Telegraph Company (USA)

ATA
Aeronautical Telecommunications Agency (USA)

ATAA
Air Transport Association of America (USA)

ATB
All Trunks Busy

ATDA
Augmented Target Docking Adapter

ATECO
Automatic Telegram Transmission with Computers

Atlas/Centaur
Launcher (General Dynamics - USA)

ATM
Asynchronous Transfer Mode

ATME
Automatic Telegram Transmission with Computers

ATMS
Automatic Transmission Measuring System

ATN OR ATTN
Attenuation

ATP
Abbreviated Test Plan

ATR
Answering Time Recorder

ATS
Advanced Technology Satellite

ATU
Arab Telecommunication Union

AURA
Astronomy research satellite (France)

AUTO
Automatic

AUTOMOON
Automatic Moon Correction

AUTON
Autonomous commanding

AUTOON
Automatic Ace Turn On

AUX EST
Auxiliary Estimator for Earth Chord

AVC
Automatic Volume Control

AVD
Alternate Voice/Data

AVRG
Average

AX
Axial

AYAME
Experimental Telecommunication Satellite (Japan)

AZ OR Az
Azimuth

B
Baud/bits per second

B-ISDN
Broadband ISDN

B-MAC
Multiplexed Analog Component (TV, type B format)

B/W
Bothway

BA
Burst Acquired

BAI
Baikonur Launch Complex (Russian Federation)

BAPTA
Bearing and Power Transfer Assembly

BAPTA OR BPTA
Bearing & Power Transfer Assembly

BATELCO
The Bahamas Telecommunication Corporation (Bahamas)

BATT
Battery

BB
BaseBand

BBC
British Broadcasting Corporation (UK)

BBD
Broadband Transmission

BBTM
Beam-to-Beam Traffic Matrix

BBU
BaseBand Unit

BC
Broadcasting

BCD
Binary Coded Decimal

BCH
Bose-Chaudhuri Hocquenghem (FEC block codes)

BCM
Binary Coded Matrix/Block Coded Modulation

BCN
Beacon

BCRU
Battery Charging and Reconditioning Unit

BCS
Block Control Signal

BCTE
Bus Command & Telemetry Electronics

BCU
Batch Control Utility

BCW
Burst Code Words

BDC
Battery Discharge Controler

BDE
Baseband Distribution Equipment

BDF
Baseband Distribution Frame

BDT
Bureau of Telecommunication Development (ITU)

BDU
Baseband Distribution Unit

BE
Beacon Explorer (NASA Satellite - USA)

BEEFS
Bit Error Ratio/Error Free Seconds

BEF
Band Elimination Filter

BEP
Bit Error Probability

BER
Bit Error Ratio

BERCONT
Bit Error Ratio Continuous

BEZEQ
The Israel Telecommunication Corp., Ltd.

BF
Branching Filter

BFDI
Bit-Frame Synchronizer Interface

BFN
Beam Forming Network

BFO
Beat Frequency Oscillator

BFS
Bit Frame Synchronizer

BFSI
Bit Frame Synchronizer Interface

BFSK
Binary Frequency Shift Keying

BH
Brinell Hardness

BHASKARA
Satellite for earth observation (India)

BHC
Busy Hour Call

BHL
Busy Hour Load

BIAS
Correction

BIE
Bearer Interface Equipment

BIH
Bureau International de l'Heure (International Time Bureau)

BINR
Basic Intrinsic Noise Ratio

BIP
Bit Interleaved Parity

BIPM
Bureau International des Poids et Mesures (International Bureau of Weights and Measures)

BIQUAD
Biquadratic Filter

Bit
A binary digit, Smallest possible unit of digital transmission

BITE
Built-In Test Equipment

BIU
Bus Interface Unit

BJT
Bipolar Junction Transitor

BLD
Binary Load Dump

BLK
Block

BM
Burst Monitor

BMLA
Burst Mode Microwave Link Analyzer

BMS
Baseband Matrix Switch

BMU
Battery Monitor Unit

BNA
Burst Not Acquired

BNQ
Burst Not Qualified

BNS
Back-up North-South Stationkeeping

BO
Backoff

BOD
Beneficial Occupancy Date

BOL
Beginning of Life

BP
Bandpass

BPF
Bandpass Filter

BPI
Bits Per Inch

BPL
Bandpass Limiter

bps OR BPS OR bit/s
Bits Per Second

BPSK
Bi-Phase Shift Keyed

BPSK, (2-PSK)
Binary phase-shift keying

BQ
Burst Qualified

BRL
Balance Return Loss

BRS
B-Mode Receiving Station

BRT
Beacon Receive Terminal

BS
Backspace

BSE
Broadcast Satellite, Experimental (Japan)

BSG
British Standard Gauge

BSI
British Standards Institute (UK)

BSM
Baseband Switch Matrix

BSP
British Standard Pipe (Thread)

BSS
B-Mode Sending Station

BST
Block the Spade Terminal Command

BSU
Baseband Switching Unit

BSWG
British Standard Wire Gauge

BSXF
Burst Synch Failure

BT
Bandwidth Time product

BTA
Burst Timing Acquired

BTE
Bench Test Equipment

BTG
Beacon Tracker Generator

BTL
Bell Telephone Laboratories (USA)

BTNA
Burst Timing Not Acquired

BTP
Burst Time Plan

BTPC
Burst Time Plan Change

BTPM
Burst Time Plan Memory

BTR
Beacon Tracker Receiver

BTS
Beacon Tracker System

BTU
British Thermal Unit

BU
Baseband Unit

BUV
Backscatter Ultraviolet Spectrometer

BVU
Brightness Value Unit

BW
Bandwidth

BWR
Bandwidth Ratio

C
Capacitance

C-band
Used loosely for satellite services in the 6/4GHz bands

C-MAC
Multiplexed Analog Component (TV, type C format)

C/D
ratio Charge/Discharge ratio

C/I
Carrier-to-Interference Ratio

C/IM3
Carrier-to-3rd Order Intermodulation Ratio

C/IMo
Carrier-to-Intermodulation Noise Density Ratio

C/N
Carrier-to-Noise Ratio

C/T
Carrier-to-Noise Temperature Ratio

C&D
Control and Display

C&DH
Control and Data Handling

C2L
Close Complementary Logic

CAA
Crew Access Arm

CAD
Computer-Aided Design (or Drafting)

CADC
Control and Display Console

CAE
Computer-Aided Engineering

CAFS
Cape Canaveral AFS

CAL
Calibrate mode

CAM
Computer Aided Manufacturing

CAMA
Centralized Automatic Message Accounting

CAN
Cancel

CANTO
Caribbean Association of National Telecommunications Operators

CAO
Completed As Ordered

CAP
Command Assistance Program

CAR
Channel Assignment Record

CAS
Collision Avoidance System

CASSA
Coarse Analog Sun Sensor Assembly

CAT
Computer Aided Tomography

CATH
Cathode

CATR
Compact Antenna (Test) Range

CATV
Cable Television

CAW
Channel Address Word

CAX
Community Automatic Exchange

CB
Citizens' Band (radio) (USA)

CBC
Canadian Broadcasting Corporation

CBCA
Constrained Beam Control Assignment

CBI
Conference Bridge In

CBS
Columbia Broadcasting System (USA)

CBTP
Condensed Burst Time Plan

CBTR
Carrier and Bit Timing Recovery

CC
Central Core

CCA
Collocated Communications Antenna

CCAFS
Cape Canaveral Airforce Station (USA)

CCAQ
Consultative Committee on Administrative Questions

CCB
Coin-Collecting Box

CCC
Control and Coordination Circuit

CCD
Charge Coupled Device

CCES
Common Control Echo Suppressor

CCI
(International Consultative Committee)

CCIF
(International Telephone Consultative Committee)

CCIR
Comite Consultatif International de Radio (International Radio Consultative Committee) (ITU)

CCITT
Comite Consultatif International des Telephones et Telegraphes (International Telephone and Telegraph Consultative Committee) (ITU)

CCKF
Continuity Checktone Failure

CCP
Communications and Control Processor

CCS
Command Coordination System

CCT
Circuit

CCTS
Coordinating Committee on Satellite Communications

CCTV
Closed Circuit Television

CCU
Central Control Unit

CCW
Counter-Clockwise

CD
Crystal Detector

CDA
Command and Data Acquisition (Station)

CDC
CCP Display Creation

CDD
Command Decryption Devices

CDE
Control and Display Equipment

CDF
Carrier Distribution Frame

CDHP
Command and Data Handling Package

CDM
Code Division Multiplex(ing)

CDMA
Code Division Multiple Access

CDN
Content Delivery Network

CDR
Critical Design Review

CDRT
Central Data Recording Terminal

CEEFAX
Trade name for a videodata system (UK)

CELTIC
Names of French digital compression equipment for telephony

CEMA
Canadian Electrical Manufacturers Association (Canada)

CENTO
Central Treaty Organization

CENTROID
Center of thruster torque pulse

CEPT
(European Conference of Postal and Telecommunications Administrations)

CES
Coast Earth Station (INMARSAT)

CESA
Canadian Engineering Standards Association

CEU
Command Extension Unit

CEVM
Consumable Electrode Vacuum Melt

CFDM
Companded Frequency Division Multiplex

CFDM/FM
Companded Frequency Division Multiplex/Frequency Modulation

CFE
Customer Furnished Equipment

CFM
Companded Frequency Modulation

CFN
Cluster Feeding Network

CFPA
C-band Full Performance Antenna

CFR
Code of Federal Regulations

CFRP
Carbon Fiber Reinforced Plastic

CG
Character Generator

CG OR cg
Center of Gravity

CG/MOI
Center of Gravity/Moment of Inertia

CGCI
Computer Generated Command Instruction

CGCIS
Computer Generated Command Instruction System

CGMS
Coordination of Geostationary Meteorological Satellites

CGPM
(General Conference of Weights and Measures)

CH
Channel

CHDB
Compatible High-Density Bipolar Code

CI
Command Interpreter

CIC
Common Interface Circuit

CID
Cathode Imaging Detector

CIFAS
French-German Industrial Consortium for Symphonie Program

CIGRE
(International Conference on Large Electric Systems)

CIMS
Coordination & Interference Management System

CIRC
International Radiomaritime Committee

CIRM
International Marine Radio Association

CISPR
(International Special Committee on Radio Interference)

CITE
Cargo Integrated Test Equipment

CITEL
Inter-American Telecommunications Committee

CKE
Zero Kinetic Energy

CKR
Receive Bit Clock

CKT
Transmit Bit Clock

CL
Closed

CLD
Command Logic Demodulators

CLE
Common Logic Equipment

CLI
Calling Line Identification

CLK
Clock

CLR
Clear

cm OR CM
cm

cm_
Square centimeter

CMC
Central Monitoring and Control

cmd OR CMD
Command

CMDR
Command Rejected

CME
Circuit Multiplication Equipment

CME/LRE
Circuit Multiplication/Low Rate Encoding Equipment

CMEA
Council on Mutual Economic Assistance

CMG
Control-Moment Gyroscope

CMI
Code Mark Inversion

CML
Current-Mode Logic

CMOS
Complementary Metal Oxide Semiconductor/Silicon

CMR
Common-Mode Rejection

CMRR
Common-Mode Rejection Ratio

CMSA
Consolidated Metropolitan Statistical Area

CMT
Continuous Mode Transmission

CMTT
(Joint Study Group for Television and Sound Transmissions)

CMU
Command Modulation Unit

CN
Check Not-Okay

CNES
Centre National d'Etudes Spatiales (France)

CNR
Carrier-to-Thermal-Noise Ratio

CNSS
Center for National Space Study

CO
Central Office

CO-ORD
Coordination Channel

Coax
Coaxial Cable

COBOL
Common Business-Oriented Language

CODAN
Carrier Operated Device Anti-Noise

Codec OR CODEC
Coder-Decoder

COHO
Coherent Oscillator

COM
Computer Output Microfilm

COMSAT
Communications Satellite Corporation

CONDOR
Satellite Network of the Andean Group

CONG
Congestion Error Control

CONT
Controller

CONUS
Continental United States (Coverage)

COP
Communications Operation Plan

COPOL OR CO-POL
Co-Polarization

COPS
Command Operations

COPSK
Coded Octal Phase Shift Keying

COPUOS
Committee on the Peaceful Uses of Outer Space (UN)

COR
Carrier-Operated Relay

CORODIM
Correlation of the Recognition of Degradation With Intelligibility Measurements

CORSA
Cosmic Radiation Satellite (Japan)

COS
Characteristic Orbital Spacing

COSAM
Co-Site Analytical Model

COSMOS
Military Satellite Network (Russian Federation)

COSTED
Committee on Science and Technology in Developing Countries (ICSU-UN)

COTS
Commercial-off-the-Shelf

CP
Circular Polarization

CPA
Co-Polar Attenuation

CPC
Clock Phase Correction

CPCC
Clock Phase Correction Control

CPE
Customer Premise Equipment

CPFSK
Continuous Phase Frequency Shift Keying

CPI
Call Progress Indicator

CPLF
Clock Phase Log File

CPM
Coded-Phase Modulation

CPPI
Consultative Panel on Public Information (UN)

CPRI
Clock Phase Reporting Interval

cps OR CPS
Cycles Per Second

CPSK
Coherent Phase-Shifting Key

CPU
Central Processing Unit

CPVE
Clock Phase Value Entry

CQ
Call "To All Stations"

CQPSK
Quaternary Phase-Shift Keying with Coherent Demodulation

CR
Carriage Return

CRA
Centro Ricerche Aerospaziali (Italy)

CRAN
Command Receive Antenna

CRBW
Carson Rule Bandwidth

CRC
Communications Research Center (Canada)

CRD
Chord

CRDM/F
Companded Frequency Division Multiplex/Frequency

CRO
Cathode Ray Oscilloscope (or Oscillograph)

CROM
Control and Read-Only Memory

CRPL
Central Radio Propagation Laboratory (USA)

CRQ
Call Request

CRRES
Combined Release and Radiation Effects Satellite(combined NASA/USAF Mission - USA)

CRT
Cathode Ray Tube

CRTO
Centre Rigionali (Italy)

CRYO
Cryogenic

CS
Calls per Second

CSC
Common Signaling Channel

CSCD
Common Signaling Channel Demodulator

CSCE
Communications Subsystem Checkout Equipment

CSCM
Common Signaling Channel Modem

CSCS
Common Signaling Channel Synchronizer

CSE
Communications Satellite for Experimental Purposes (Japan)

CSELT
Centro Studi e Laboratori Telecomunicazione (Italy)

CSG
Centre Spatial Guyanais (Guiana Space Center)

CSM
Communications System Monitor

CSM/CSME
Communications Systems Monitor(ing)/Equipment

CSME
CSM Equipment

CSOC
Consolidated Space Operations Center

CSSB
Companded Single Sideband

CSTD
Committee on Science and Technology for Development

CSU
Channel Service unit

CSW
Channel Status Word

CT
Center Tap

CTC
Common Telegraphy Channel

CTCA
Constrained Terminal Control Assignment

CTE
Channel Translating Equipment

CTL
Control

CTP
Command and Telemetry Processor

CTR
Configuration Track Record

CTTE
Common TDMA Terminal Equipment

CTU
Central Telemetry Unit

CU
Crosstalk Unit

CUC
Computer Users' Committee

CVA
Constant Volume Amplifier

CVD
Chemical-Vapor Phase Deposition

CVM
Command Verification Module

CVSD
Continuous Variable Slope

CVSDM
Continuously Variable-Slope Delta Modulation

CW
Carrier Wave

CWBS
Contract Work Breakdown Structure

CX
Coin Box

CXR
Carrier

D-MAC
Multiplexed Analog Component (TV, type D format)

D.A.T.E.
Duly Authorized Telecommunications Entity

d.p.
Drip-Proof

D/
Diameter/wavelength ratio

D/A
Digital to Analog

D/C
Downconverter

D/L
Downlink

D2-MAC
Multiplexed Analog Component (TV, type D2 format)

DA
Demand Assignment

DAC
Digital to Analog Converter

DACCS
Digital Access Cross-Connect System

DAIT
Demand Assigned International Terminal

DAMA
Demand Assigned Multiple Access

DAND
Despin Active Nutation Damper

DASCPC/QPSK
Demand Assigned Single-Channel-Per-Carrier/Quadrature Phase Shift Keying

DASS
Demand Assignment Signaling and Switching Unit

DATE
Duly Authorized Telecommunications Entity

DATTS
Data Acquisition Telecommand and Tracking Station

DAV
Data-Above-Voice

DAVC
Delayed Automatic Volume Control

dB OR DB
Decibel

dB/K
Decibels per Degree Kelvin

dBC
C-scale Sound Level in Decibels

dBm
Decibels Relative to one Milliwatt

dBm0
dBm referred to or measured at a point of zero transmission level(0TLP)

dBm0p
dBm Point psophometrically weighted referred to or measured at a point of zero transmission level (0TLP)

DBMS
Data Base Management System

DBP
Deutsche Bundepost (Germany)

DBS
Direct Broadcast Satellites

DBTR
Digital Bit Timing Recovery

dBV
Decibels Above 1 Volt

dBW
Decibels relative to one Watt

DC OR d.c.
DC Directional Coupler

DC/DC
Direct Current to Direct Current

DCA
Defense Communications Agency (USA)

DCC
Demand Assignment Call Connect

DCCC
Double-Current Cable Code

DCD
Data Carrier Detector

DCDR
Data Collection and Data Relay

DCE
Data Communications Equipment Data Circuit Terminating Equipment

DCM
Device Control Management

DCME
Digital Circuit Multiplication Equipment

DCME/DCMS
Digital Circuit Multiplication Equipment/System

DCN
Document Change Notice

DCP
Data Collection Platform

DCPSK
Differentially Coherent Phase Shift Keying

DCR
Document Change Request

DCRT
Data Collection Receive Terminal

DCS
Data Collection System

DCTL
Direct-Coupled Transistor Logic

DCTV
Despin Compartment Thermal Vacuum Test

DCU
Data Concentrator Unit

DD/C
Dual Downconverter

DDC
Double Downconverter

DDD
Direct Distance Dialing

DDF
Digital Distribution Frame

DDI
Direct Digital Interface

DDIE
Direct Digital Interface Equipment

DDP
Digital Data Processor

DDS
Digital Data System

DEC
Declination

DEF
Defined

DELTA
Launcher (McDonnell Douglas - USA)

Delta-P
Pressure Difference

Demod
Demodulator

Demux OR DEMUX
Demultiplexer

DES
Digital Encryption Standard

DET
Detector

DEV
Deviation

DF
Direction Finding

DFS
Domestic satellite network (Germany)

DG
Differential Gain

DGL
Device Independent Graphics Library

diac
Diode AC Switch

DID
Direct Inward Dialing

DIOS
Digital In-band Open-Look Synchronization

DIP
Dual In-line Package

DIRA
Digital Integrating Rate Assembly

DIRT
Decide-In-Real-Time commanding

DISC
Disconnect command

DITEC
Digital Television Communication System

DIUR
Diurrnal

DIV
Data-In-Voice

DLC
Data Link Receive (Timeplex)

DLE
Data Link Escape

DLF
Direct Through-Connection Filter

DM
Delta Modulation

DM/PSK
Delta Modulation/Phase Shift Keyed

DMA
Direct Memory Access

DME
Distance Measuring Equipment

DMM
Digital Multimeter

DMSP
Defense Meteorological Satellite Program (USA)

DNI
Digital Non-Interpolated

DNIC
Data Network Identification Code

DNTX
Do Not Transmit

DOC
Digital Operations Center

DOD
Department of Defense (USA)

DOM
Domestic

DOMP
Distributed Orbital Mechanical Process

DOMSAT
Domestic Satellite System

DOPSK
Differential Offset Phase Shift Keying

DOS
Disk Operating System

DOV
Data-Over-Voice

DOVAP
Doppler Velocity and Position

DP
Differential Phase

DPA
Destructive Physical Analysis

DPC
Data Processing Center

DPCM
Differential Pulse Code Modulation

DPDT
Double Pole Double Throw (switch)

DPL
Deployed

DPM
Digital Panel Meter

DPSK
Differential Phase Shift Keyed

DPST
Double Pole Single Throw (switch)

DPTC
Digital Program Track Controller

DPU
Data Processing Unit

DQPSK
Differential Quadrature PSK

DR
Data Rate

DRE
Directional Reservation Equipment

DRGS
Direct Readout Ground Station

DRL
Contract Data Requirements List

DRO
Dielectric Resonator Oscillators

DRP
Directional Radiated Power

DRS
Direct Reception Station

DRT
Data Recording Terminal

DS
Data Speech

DS-3
Digital Signal 3

DS1, etc.
Digital Services

DSB
Direct Sounding Broadcast

DSB-SC-AM
Double Sideband-Suppressed Carrier-Amplitude Modulation

DSB-SC-AM w/QM
Double Sideband-Suppressed Carrier-Amplitude Modulation with Quadrature Multiplexing

DSB-SC-ASK
Double Sideband-Suppressed Carrier-Amplitude Shift Keyed

DSCS
Defense Satellite Communications System (USA)

DSDU
Despun Squib Driver Unit

DSE
Data Switching Exchange

DSI
Digital Speech Interpolation

DSI-AC
Digital Speech Interpolation Assignment Channel

DSIP
DS Interface Package

DSL
Deep Scattering Layer

DSM
Dual Synchronous Module

DSMDU
Despun Stepper Motor Driver Unit

DSN
Domestic satellite network (Israel)

DSP
Define Switch Parameter (Timeplex)

DSR
Data Set Ready

DSS
Digital Sun Sensor

DST
Direct Sounding Transmission

DSU
Disk Storage Unit

DTC
Detection Threshold Computer

DTE
Data Terminal Equipment

DTI
Data Transfer Interface

DTL
Diode-Transistor Logic

DTM
Digital Termination Module

DTMF
Dual Tone Multiple Frequency

DTP
Detailed Test Plan

DTR
Down-Time Ratio

DUC
Double Upconverter

DUS
Data Utilization/User Station

DUT
Device Under Test

DUV
Data Under Voice

DVLP
Development Center (Intelsat's)

DVM
Digital Volt Meter

DVT
Design Verification Test

DWN
Down

DX or dx
DX Distance reception

e.i.r.p.
EIRP Equivalent Isotropically Radiated Power

e.m.r.p,
Effective Monopole-Radiated Power

e.r.p.
Effective Radiated Power

E/A
Events and Alarms subsystem

E/Q
Energy per Unit Charge

E/S
Earth Station

E/W
East/West

EAC
Engineering Assistance Contract

EAGE
Electrical Aerospace Ground Equipment

EAROM
Electrically-Alterable ROM

EAS
Events and Alarms System

Eb/No
Energy per Bit to Noise density ratio

EBCDIC
Extended Binary-coded Decimal Interchange Code

EBHC
Equated Busy Hour Call

EBR
Electronic Beam Recorder

EBU
European Broadcasting Union

EC
Earth Chord

ECA
Earth Chord measured from earth sensor A

ECB
Earth Chord measured from earth sensor B

ECC
Eccentricity

ECD
Echo Control Device

ECE
Economic Commission for Europe

ECH
Earth Coverage Horn

ECL
Emitter Coupled Logic

ECLA
Economic Commission for Latin America

ECM
Error Correction Mode

ECMA
European Computer Manufacturers Association

ECO
Electron-Coupled Oscillator

ECOM
Electronic Computer-Originated Mail

ECR
Earth Centered Rotating

ECRA
Electrical Contact Ring Assembly

ECS
European Regional Communications Satellite System

ECU
Electrical Conversion Unit

ECWA
Economic Commission for Western Asia

EDA
Electronic Despun Antenna

EDC
Effective Date of Contract

EDF
Energy Dispersal Function

EDI
Electronic Data Interchange

EDOR
Early Definition of Requirements

EDP
Electronic Data Processing

EDPM
Electronic Data Processing Machine

EDPS
Experiment Data and Power System

EDTV
Enhanced Definition Television

EDW
Energy Dispersion Waveform

EEA
Electrostatic Energy Analyzer

EFdS
Error Free Deciseconds

EFI
Error-Free Intervals

EFS
Error-Free Seconds

EFT
Electronic Funds Transfer

EFTA
European Free Trade Association

EG/No
Energy per bit to Noise Density Ratio

EHF
Extremely High Frequency (Miriametric waves)

EIA
Electronic Industries Association (USA)

EIRESAT
Satellite network (Ireland)

EISCAT
European Institute Scatter Facility

EJ
Electronic Journalism

EJF
Estimated Junction Frequency

EKRAN
Statsionar Satellite (Russian Federation)

EL
Elevation

ELEA
Earth Leading Edge A

ELEB
Earth Leading Edge B

ELF
Extremely Low Frequency

ELT
Emergency Locater Transmitter

ELU
Existing Carrier Line-Up

ELV
Expendable Launch Vehicles

EM
Electromagnetism

EMA
Extended Memory Access

EMC
Electromagnetic Compatibility

EMC FOM
Electromagnetic Compatibility Figure of Merit

EME
Earth-Moon-Earth

EMF
Electromagnetic Force

EMI
Electromagnetic Interference

Emin
Minimum Usable Field Strength

EMP
Electromagnetic Pulse

EMS
Electronic Message Service

EMU
Extra-vehicular Maneuvering Unit

ENA
Enabled

ENC
Encoding unit control process

ENG
Electronic News Gathering

Enom
Nominal Usable Field Strength

ENTEL
Empresa Nacional de Telecomunicaciones S.A. (Bolivia), (Chile),(Peru)

ENV
Envelope

EOC
Edge of Coverage

EOD
End of Dialing

EOL
End Of Life

EOOS
Early Orbit Operations Services (Intelsat)

EOS
Earth Observation Satellite

EOW
Engineering Order Wire

EPC
Electronic Power Conditioner/Converter

EPDS
Experiment Power and Data Systems

EPI
Elevation Position Indicator

EPIRB
Emergency Position Indicating Radio Beacon

EPROM
Erasable PROM

EQM
Engineering Qualification Model

ER&S
Exploratory Research and Studies

ERB
Earth Radiation Budget

ERBE
Earth Radiation Budget Experiment

ERL
Echo Return Loss

EROS
Earth Resources Observation Satellite (USA)

ERP
Effective Radiated Power

ERR
Error

ERS
Earth Resources Satellite

ERSOS
Earth Resource Survey Operational System

ERTS
Earth Resources Technology Satellite (USA)

ERU
Encoding Rate Update

Es or ES
Es (sporadic E)

ESA
Earth Station Antenna

ESC
Engineering Service Circuit/Channel

ESCAP
Economic and Social Commission for Asia and the Pacific

ESCES
Environmental Satellite Communication Earth Station (India)

ESD
Electrostatic Discharge

ESM
Eastern Space and Missile Center

ESMR
Electrically Scanning Microwave Radiometer

ESOC
European Space Operations Center

ESPA
Earth Sensor Processor Electronics Package A

ESPB
Earth Sensor Processor Electronics Package B

ESPE
Earth Sensor Processing Electronics

ESRANGE
European Sounding Rocket Landing Range (ESA)

ESRO
European Space Research Organization

ESS
Electronic Switching System

ESSA
Environmental Survey Satellite

EST
Estimate

ESTEC
European Space Research and Technology Center

ESU
Empty Signal Unit

ETA
Estimated Time of Arrival

ETD
Estimated Time of Departure

ETF
Error Threshold Firing

Ethernet
A family of frame-based computer networking technologies for local area networks (LANs).

ETS
Electronic Translator System

ETSI
European Telecommunication Standards Institute

ETT
Electrothermal Thrusters

ETV
Educational Television

EU OR Eu
EU Engineering Unit

EUMETSAT
European Organization for the Exploration of Meteorological Satellites

EURECA
European Retrievable Carrier (Spacecraft)

EUROCONTROL
European Organization for Safety of Air Navigation

EURONET
European Public Network (Data)

EUROSAT
Organization to implement a European system of telecommunications and TV by satellite

EUROSPACE
European Industrial Space Study Group

EUROVISION
European and Mediterranean TV services

EUTELSAT
European Telecommunications Satellite Organization

EUV
Extreme Ultraviolet

EUVE
Extreme Ultraviolet Explorer (NASA Satellite)

eV
Electron Volt

EVA
Extra-Vehicular Activity

EVR
Electronic Video Recording

EW
Electronic Warfare

EXCLUSIVE-NOR
Type of Logic Circuit

EXCLUSIVE-OR
Type of Logic Circuit

EXOS
Exospheric Satellite (Japan)

EXOSAT
European X-Ray Observation Satellite (ESA)

EZ
Ephemeris Time

F
Farad

F/D
Focal Length to Diameter Ratio

f/o
Fiber Optic

F/V
Frequency-to-Voltage

FACC
Ford Aerospace & Communications Corporation

FACT
Fabrication And Continuity Test Program

FAS
Frame Acquisition and Synchronization

FAX
Facsimile

FBSS
Full Band Spread Spectrum

FC or Fc
FC Forecast Center Station

FCC
Federal Communications Commission (USA)

FCD
Facility Completion Date

FCS
Frame Check(ing) Sequence

FD
Functional Description

FD-PSK
Frequency Differential Phase-Shift Keyed System

FDB
Fahrenheit Dry Bulb

FDC
Flight Dynamics and Commanding

FDFM
Frequency Division/Frequency Modulation

FDM
Frequency Division (or Domain) Multiplex

FDM/CFM
Frequency Division Multiplex/Companded

FDM/FM
Frequency Division Multiplex/Frequency Modulation

FDMA
Frequency Division Multiple Access

FDR
Final Design Review

FDS
Flight Dynamic System

FDSS
Fine Digital Sun Sensor

FDSSA
Fine Digital Sun Sensor Assembly

FDSSE
Fine Digital Sun Sensor Electronics

FE
Fast Ethernet

FEC
Forward Error Correction

FET
Field Effect Transistor

FF
Flip Flop (bistable electronic circuit)

FFC
Feed Forward Compensation

FFP
Firm Fixed Price

FFT
Fast Fourier Transform

FGGE
First GARP Global Experiment

FH
Frequency Hopping

FIFO
First In-First Out

FIL
Filter

FINTEL
Fiji International Telecommunications Limited (Fiji)

FIR
Flight Information Region

FIS
Flight Information Service

FIT
Failure in Time

FITE
Forward Interworking Telephony Event

FITS
Failures in 109 hours

FL
Fuel

FLS
Free Line Signal

FLTR
Filter

FLTSATCOM
US Navy Satellite Communications System (USA)

FLU
Full Line Up

FLV
Fuel Valve

FM
Frequency Modulation

FM/FDMA
Frequency Modulation/Frequency Division Multiple Access

FMA
Ferrite Modular Assembly

FMC
Fallback Master Clock

FMEA
Failure Modes and Effects Analysis

FMECA
Failure Modes, Effects, and Criticality Analysis

FMFB
Frequency Modulation Feedback

FMVT
Frequency Modulation Voice Telegraphy

FMW
Fixed Momentum Wheel

FMWA
Fixed Momentum Wheel Assembly

FOM
Factor of Merit

FORTRAN
Formula Translation

FOS
Follow-On Satellite (Intelsat)

FOT
Optimum Working Frequency

FOV
Field of View

FP
Full Period

FPA
Final Power Amplifier

FPR
Flat Plate Radiometer

FRMR
Frame Rejected

FRR
Fast Reroute

FRS
Forward Ready Signal

FRU
Field Replaceable Unit

FRXD
Fully Automatic Reperforator Transmitter Distributor

FS
Figure Shift

FSB
Frame Synchronizer and Buffer

FSD
Full-Scale Deflection

FSF
Fading Safety Factor

FSK
Frequency Shift Keying

FSS
Fixed Satellite Service

FT
Foot (unit of measure)

FT_
Foot Squared

FT/MIN
Foot per Minute

FT/S
Foot per Second

FTF
Fixed Time Firing

FTP
File Transfer Protocol

FUL
Fuel

FVDA
Fully Variable Demand Access

FWB
Fahrenheit Wet Bulb

FWD
Forward

G
Gain

G-M tube
Geiger-Mueller tube

G/T
Gain to Noise Temperature Ratio

GaAs
Gallium Arsenide

GaAsFET
Gallium Arsenide Field Effect Transistor

GAGR
Group Automatic Gain Regulator

GALAXY
Domestic Satellite (Hughes Communications - USA)

GARP
Global Atmospheric Research Program

GARS
Geological Applications for Remote Sensing

GAS
Special Autonomous Study Group (I.T.U.)

GATT
General Agreement on Tariffs and Trade

GbE OR GigE
Gigabit Ethernet

GCE
General Certificate of Education (UK)

GCS
Ground Control System

GDF
Group Distribution Frame

GDL
Satellite System (Luxembourg)

GDMO
General Definition of Managed Objects

GDN
Graphic Display Network

GDP
Gross Domestic Product

GDPS
Global Data Processing System (WMO)

GE
General Electric (USA)

GEMS
Global Environment Monitoring System (UN)

GEO
Geosynchronous (geostationary) Equatorial Orbit

GEO-IRS OR GEOIRS
Geostationary Orbit Infrared Sensor

GEOS
Geodetic Earth-Orbiting Satellites (NASA)

GEU
Ground Encryption Unit

GFE
Government Furnished Equipment

GFRP
Graphite

GGSE
Gravity Gradient Stabilization Experiment Satellite (USA)

GGTS
Gravity Gradient Test Satellite

GHA
Greenwich Hour Angle

GHIUD
Global Human Information Use Per Decade

GHz
Gigahertz (1 billion cycles per second)

GIP
Group Interface Processor

GLB
Global antenna

GM
Gravitational parameter

GMA
Gated Mode Acquisition

GMC
General Motors Corporation

GME
Group Modulating Equipment

GMS
Geostationary Meteorological Satellite

GMT
Greenwich Mean Time

GN
Gain

GNC
Ground Nutation Controller

GND
Ground/Earth

GOES
Geosynchronous Operational Environmental Satellite (USA)

GORC
Global Operations Representative Conference

Gorizont
Communication Satellite (Russian Federation)

GOS
Global Observing System (WMO)

GP OR Gp
GP General Processor

GPC
General Purpose Computer

gpDm
Geopotential Decameter (1 ghDm = 9,81m)

GPIB
General Purpose Interface Bus

GPS
Global Positioning Satellite/System (US)

GRARR
Goddard Range and Range Rate (USA)

GRD
Ground Resolved Distance

GRFP
Graphite-Fiber-Reinforced Plastic

GRGS
(Space Geodesy Research Group)

GRID
Global Resource Information Database

GRND
Ground

GRP
Group

grt
Gross Registered Tons

GS
Group Separator

GSB
Global Storage Block

GSE
Ground Support Equipment

GSFC
Goddard Space Flight Center (USA)

GSO
Geostationary Satellite Orbit

GSTAR
Domestic Satellite Network (Owned by GTE Satellite Corporation - USA)

GTE
General Telephone & Electronics, Inc. (USA)

GTM
Global Traffic Meeting (Intelsat)

GTO
Geostationary (or geosynchronous) Transfer Orbit

GTS
Global Telecommunications System (WMO)

GUATEL
Empresa Guatemalteca de Telecomunicaciones (Guatemala)

GUI
Graphical User Interface

GWN
Gaussian White Noise

H
Microhenry

HAC
Hughes Aircraft Company (USA)

HAD
Half Amplitude Duration

HAKUCHO
Cosmic Radiation Satellite (same as CORSA) (Japan)

HCE
Heater Control Electronics

HD
High Definition

HD-SDI
High Definition-Serial Digital InterfaceHigh Definition

HDB
High Density Bipolar Code

HDLC
High Level Data Link Control

HDRSS
High Data Rate Storage System

HDTV
High Definition Television

HDX
Half Duplex (syn.: semi-duplex)

HE
Heat Exchanger

HEAO
High-Energy Astronomy Observatory

HELIOS
Experimental Satellite (Germany)

HELVESAT
Broadcast Satellite System (Switzerland)

HEM
Hughes Engineering Module

HEMT
High Electron Mobility Transistors

HEOS
Highly Eccentric Orbit Satellite

HF
High Frequency (3,000 - 30,000 Khz)

HILAT
High Latitude Satellite (DOD - USA)

HIRS
High Resolution Infrared Sounder

HISPASAT
Satellite Network (Spain)

HL
Half-Life (radioactive)

HLL
High-Level Language

HLLV
Heavy Lift Launch Vehicle

HLX
Helix

HM
Hybrid Modulation

HNS
Hughes Network Systems

hp OR HP
HP Hewlett-Packard (company, USA)

HPA
High Power Amplifier

HPBW
Half-Power Beam Width

HPF
Hazardous Processing Facility

HPI
Height Position Indicator

HPIB
Hewlett Packard Interface Board

HPM
Hybrid Phase Modulation

HQ
Intelsat Headquarters

HQES
Headquarters Earth Station

HRC
Hypothetical Reference Circuit

HRDC
Hypothetical Reference Digital Circuit

HRDP
Hypothetical Reference Digital Path

HRFAX
High Resolution Facsimile

HRIR
High Resolution Infrared Scanning System

HRP
Historical Storage and Retrieval Processor

HRX
Hypothetical Reference Connection

HSE
Host Station Equipment

HT
Horizontal Tabulation

HTR
Heater

HV
High Voltage

HVM
High Voltage Module

HW
Hardware

HYPACE
Hybrid Programmable Attitude Control Electronics

Hz
Hertz (Cycles per Second)

I/O
Input/Output

I&D
Integrate and Dump Detection

IAAB
Inter-American Association of Broadcasting

IAE
AInternational Atomic Energy Agency

IAF
International Astronautical Federation

IAGA
International Association of Geomagnetism and Aeronomy

IAGC
Instantaneous Automatic Gain Control

IAI
Initial Address Information

IAP
Initial Acquisition Phase

IARU
International Amateur Radio Union

IAT
Intermediate Attitude Trim

IATA
International Air Transport Association

IATE
International Accounting and Traffic Analysis Equipment

IAU
International Astronomical Union

IB
Input Buffer

IBC
Interface Buffer Controller

IBI
Intergovernmental Bureau for Informatics

IBRD
International Bank for Reconstruction and Development (World Bank)

IBS
Intelsat Business Services

IBS/FT
Intelsat Business Service Full Time

IBTO
International Broadcasting and Television Organization

IC
Index Correction

ICAO
International Civil Aviation Organization

ICB
Incoming Call Barred

ICC
Intelsat Communications Center

ICDSC
International Conference on Digital Satellite Communications

ICI
International Commission on Illumination

ICN
Idle Channel Noise

ICON
Intelsat Information and Communications Network

ICPO
International Criminal Police Organization (Interpol)

ICRP
International Commission on Radiological Protection

ICS
International Chamber of Shipping

ICSA
Intelsat Computer Systems Architecture document

ICSAB
International Civil Service Advisory Board

ICSU
International Council of Scientific Unions

ICW
Interrupted Carrier Wave

ID
Identification

IDA
International Development Association

IDB
Integrated Data Base

IDC
Image Dissector Camera

IDCC
International Data Communications Center

IDCP
International Data Collecting Platform

IDDD
International Direct Distance Dialing

IDF
Intermediate Distribution Frame

IDN
Integrated Digital Network

IDP
Integrated Data Processing

IDR
Intermediate Data Rate

IDTV
Improved Definition TV

IE
Index Error

IEA
International Energy Agency

IEC
International Electrotechnical Commission

IEE
Institute of Electrical Engineers (UK)

IEEE
Institute of Electrical and Electronic Engineers (USA)

IEEIE
Institute of Electrical and Electronic Incorporated Engineers

IERE
Institution of Electronics and Radio Engineers

IES
Incoming Echo Suppressor

IESS
Intelsat Earth Station Standards

IETEL
Instituto Ecuatoriano de Telecomunicaciones (Ecuador)

IEU
Interface Electronics Unit

IEV
International Electrotechnical Vocabulary

IF
Intermediate Frequency

IFA
Intermediate Frequency Amplifier

IFD
In-Flight Disconnects

IFE
Intelsat Furnished Equipment

IFF
Intensity Fluctuation Factor

IFIP
International Federation for Information Processing

IFL
Inter-Facility Link

IFOV
Instantaneous Field of View

IFR
Instrument Flight Rules

IFRB
International Frequency Registration Board (ITU)

IFS
Intelsat Financial System

IFTC
International Film and Television Council

IGFET
Insulated-Gate Field Effect Transistor

IGOSS
Integrated Global Ocean Station System

IGRF
International Geomagnetic Reference Field

IIC
Individual Interactive Commanding

IICM
Intelsat Intersystem Coordination Manual

IISL
International Institute of Space Law

ILC
Inter-Link Controller (Timeplex Card)

ILD
Injection Laser Diode

ILS
Integrated Logistical Support

IM
Intelsat Management

IMC
International Maintenance Center

IMD
Intermodulation Distortion

IMMED
Immediate

IMO
International Maritime Organization (formerly IMCO)

IMP
Interface Message Processor

IMPATT
Impact Avalanche Transit Time (diode)

IMPD
Impedance

IMUX
Input Multiplexer

in_
Square inch

in/s
Inches per second

INAG
Ionospheric Network Advisory Group

INC
Inclination

INCATEL
Instituto Centroamericano de Telecomunicaciones (Central American Institute of Telecommunications)

INJ
Injector

INMARSAT
International Maritime Satellite Organization

INSAT
Domestic Satellite Network (India)

INTEL
Instituto Nacional de Telecomunicaciones (Panama)

INTELPOST
Name of international organization created to conduct experimental electronic mail transmissions

INTELSAT
International Telecommunications Satellite Organization

INTERCOSMOS
International Research Satellites (Russian Federation)

INTERSPUTNIK
International Space Telecommunication Organization (Russian Federation)

INUKSAT
Domestic Satellite System (proposed by Denmark)

IOB
Inter-Organization Board for Information Systems and Related Activities

IOC
Input/Output Controller

IOCTF
Intelsat Operations Center TDMA Facility

IOO
Inclined Orbit Operation

IOR
Indian Ocean Region

IOT
In-Orbit Test

IOTA
Intelsat Online Transaction Access

IOTE
In-Orbit Test Equipment

IP
Index Pulse

IPA
Intermediate Power Amplifier

IPCE
Interface Power Conditioning Electronics

IPDC
International Program for Development of Communications

IPG
Index Pulse Generator

IPP
International Phototelegraph Position

IPS
Input Processing and Service request generation block

IPTC
International Press Telecommunications Council

IPU
Information Processing Ability

IR
Information Rate

IRB
Inoperative Reference Burst

IRE
Institute of Radio Engineers

IRIG
Inter-Range Instrumentation Group

IRLS
Interrogation, Recording and Location System

IRP
International Routing Plan

IRS
Information Receiving Station

IRTV
Infra-Red Thermal Vacuum

IRU
Indefeasible Right of Use

IS
Information Separator

ISAS
Institute of Space and Aeronautical Science (Japan)

ISB
Independent Side Band

ISC
Intelsat Service Center

ISCC
International Service Coordination Center

ISCOM
Satellite for Communication Technology (India)

ISCS
Integrated Satellite Conrol Systems

ISEE
International Sun-Earth Explorers

ISF
International Shipping Federation

ISIS
International Satellite for Ionospheric Studies (USA/Canada)

ISL
Inter Satellite Link

ISM
Industrial, Scientific, and Medical Applications

ISMC
International Switching Maintenance Center

ISO
International Standards Organization

ISP
Specific Impulse

ISPC
International Sound Program Center

ISPO
Intelsat Spacecraft Project Office

ISPRS
International Society for Photogrammetry and Remote Sensing

ISR
Intelsat System Record

ISRO
Space Research Organization (India)

ISS
Information Sending Station

IST
Integrated System Test

ISTC
Integrated System Test Complex

ISTN
Integrated Switching and Transmission Network

ISU
Independent Signal Unit

ITA
Independent Television Authority (UK)

ITAF
Intelsat Technical Annex Facility

ITALSAT
Italian Communication Satellite System (Domestic Service - Italy)

ITC
International Television Center

ITCC
International Technical Control Center

ITDB
Integrated Traffic Data Base

ITE
International Telephone Exchange

ITM
International Transmission Maintenance

ITMC
International Transmission Maintenance Center

ITOS
Improved TIROS Operational Satellite (NDAA - USA)

ITPC
International Television Program Center

ITPR
Infrared Temperature Profile Radiometer

ITR
Intelsat Test Record

ITS
Insertion Test Signal

ITT
International Telephone and Telegraph Company (USA)

ITU
International Telecommunications Union

IUCAF
Inter-Union Commission on Allocation of Frequencies for Radio Astronomy and Space Science

IUE
International Ultraviolet Explorer

IUGG
International Union of Geodesy and Geophysics

IUPAP
International Union of Pure and Applied Physics

IUS
Inertial Upper Stage

IXC
Interexchange Carrier

JASC
Japan Sea Cable

JCL
Job Control Language

JF
Junction Frequency

JFET
Junction Field Effect Transistor

Jitter
The deviation in the time it takes for packets that are part of the same file to traverse the network, compared with the average delay time for all of the packets.

JIU
Joint Inspection Frequency

JPCD
Just Perceptible Color Difference

JPL
Jet Propulsion Laboratories (USA)

JRD
Joint Requirements Development

JSC
Johnson Space Center (USA)

JSD
Justification Service Digit

K or k
K Boltzmann's Constant

K-band
Frequency Spectrum 10.9 to 36 GHzK-band

kA
Kiloampere

Ka-band
Loosely used for 30/20 GHz satellite systems

KAG
Kagoshima Space Center (Japan)

kb
Kilobit

kb/s OR kbit/s OR kbps
Kilobits Per Second

KERMA
Kinetic Energy Released in Material

keV
Kiloelectron volt

KFPA
K-band Full Performance Antenna

Kg
Kilogram

kH
Kilohenry

kHz
Kilohertz (1000 cycles per second)

kJ
Kilojoules

KLY
Klystron

km(s)
Kilometer(s)

KP
Start of Pulsing

KSC
Kennedy Space Center (USA)

Ku-band
Loosely used for 10.7 to 18 GHz satellite systems

kV
Kilovolt

kVA
Kilovoltampere

kW
Kilowatt

kWh
Kilowatt-hour

L
Inductance

L-band
Frequencies in the spectral region of 1.5 GHz

L-SAT
Experimental Satellite Network (ESA)

LAE
Liquid Apogee Engine

LAGEOS
Laser Geodynamic Satellite (USA)

LAM
Liquid Apogee Motor

LAMAR
Large Area Modular Array of Reflectors

LAMMR
Large Antenna Multifrequency MW Radiometer

LAN
Local Area Network

LANDSAT
Earth Resources Survey Satellite (USA)

LAP
Link Access Protocol/Procedure

LAPB
Link Access Protocol Balanced

LAS
Low-Altitude Observation Satellite

LASCR
Light-Activated Silicon-Controlled Rectifier

LASCS
Light-Activated Silicon-Controlled Switch

LASER OR laser
Light Amplification by Stimulated Emission of Radiation

LASSII
Low Altitude Satellite Studies of Ionosphere

LAST
Large Aperture Scanning Telescope

LAT
Latitude

LATA
Local Area Transport Arrangement

LB
Local Battery

LBS
Liquid Bipropellant Subsystem

LC
Inductance

LCC
Launch Control Center (Intelsat)

LCD
Liquid Crystal Display

LCH
Latch

LCM
Load Current Monitor

LCMU
Load Current Monitor Unit

LDD
Linear Delay Distortion

LDM
Linear-Delta Modulation

LDOE
Longitude Drift/Orbit Eccentricity

LEAC
Laboratory Engineering Assistance Contract

LEASAT
U.S. Military Satellite Network (USA)

LEC
Local Exchange Carrier

LED
Light Emitting Diode

LEM
Logical End of Media

LEO
Low Earth Orbit

LETF
Launch Equipment Test Facilities

LF
Line Feed

LFM
Link Framing Module

LHA
Local Hour Angle

LHCP
Left Hand Circular Polarization

LIDAR
Light Detection and Ranging

LIFO
Last In - First Out

LINCOMPEX
Linked Compressor and Expander

LIPS
Link Performance Simulation Program

LK
Lock

LLF
Line Link Frame

LLIP
Launch Loads Instrumentation Processor

LM or Lm
LM Limits Program

LMA
Limited Motion Antenna

LMS
Level Measuring Set

LMSS
Land Mobile Satellite Service

LMT
Local Mean Time

LMTR
Limiter

LNA
Low-Noise Amplifier

LNB
Low-Noise Block-Down Converter

LNC
Low Noise Converter

LNR
Low Noise Receiver

LO
Local Oscillator

logamp
Logarithmic Amplifier

LON
Longitude

LOPs
Omega Lines of Position

LOR
Loran

LORAN-C
Long Range Navigational System

LOS
Line of Sight

LOUTCH
Ku-band Satellite Networks (Russian Federation)

LOX
Liquid Oxygen

LP
Line-up Preparations

LPA
Low Power Amplifier

LPC
Linear predictive coding

LPE
Liquid Phase Epitaxy

LPF
Low Pass Filter

LPS
Launch Process System

LRC
Langley Research Center (USA)

LRE
Low Rate Encoding

LRE/DSI
Low Rate Encoding with Digital Speech Interpolation

LRFAX
Low Resolution Facsimile

LRG
Launch Risk Guarantee

LRIR
Limb Radiance Inversion Radiometer

LRPM
Long Range Planning Model

LRR
Launch Readiness Review

LS
Letter Shift

LSB
Least Significant Bit

LSD
Least Significant Digit

LSE
Line Signaling Equipment

LSI
Large Scale Intigration

LSM
Line Switch Marker

LSO
Line Signaling Oscillator

LSP
Label Switch Path

LSR
Label Switch Router

LST
Large Space Telescope (NASA Satellite - USA)

LSU
Leading Signal Unit

LTC
Local Telephone Circuit

LTOM
Less Than One Minute

LTOS
Less Than One Second

LTT
Lower-tier test

LU
Line-Up

LUF
Lowest Usable Frequency

LUXSAT
Satellite Network (Luxembourg)

LV
Latched Valve

M bit/s OR MB/s OR Mbps
Megabits per second

M or m
M Mega/Million

m_
Square meter

mA OR MA
mA Milliampere

MAC
Multiplexed Analogue Components

MAD
Monitoring and Diagnostic Unit

MAG
Magnitude

MAGE
Mechanical Aerospace Ground Equipment

MAMSK
Multitone AMSK

MAP
Middle Atmosphere Component

MAPS
Measurement of Pollution from Satellite

MARECS
Maritime Experimental Comsat System (ESA) (formerly MAROTS)

MARISAT
Maritime Satellite System (USA)

MAS
Multi-Administration (satellite) System

maser OR MASER
Microwave Amplification by Stimulated Emission of Radiation

MAWG
Mutual Aid Working Group

MAXIT
Maximum Interference Threshold

MB
Metric Burst

MBA
Multiple Beam Antenna

MBB
Messerschmitt-Bolkow-Blohm (Germany)

MBC
Miniature beryllia circuit

MBPC
Multiple Burst Per Carrier

MBps
Megabits Per Second

MBPT
Multiple Burst Per Transponder (or Transmitter)

MBTA
Multiple Beam Torus Antenna

MBTP
Master Burst Time Plan

MC
Maintenance Center

MCC
Master Control Console

MCE
Motor Control Electronics

MCH
Map Change Handler

MCLF
Multichannel Loading Factor

MCPC
Multiple Channels Per Carrier

MCS
Maritime Communications Subsystem

MCU
Monitor and Control Unit

MCVFT
Multichannel Voice Frequency Telegraphy

MCW
Memory Control Word

MD
Multi-Destinational

MDA
Mechanically Despun Antenna

MDE
Motor Drive Electronics

MDF
Main Distribution Frame

MDFD
Multi-Destination Full Duplex

MDHD
Multi-Destination Half Duplex

MDS
Minimum Discernible Signal

MDTA
Modulatdor-Demodulator Translator Assembly

MDUS
Medium Data Utilization Station (Australia)

ME
Managed Element

MECH
Mechanism

MECO
Main Engine Cutoff

Mega
Million

MELCO
Mitsubishi Electric Corporation (Japan)

MEM
Memory

MEOP
Maximum Expected Operating Pressure

MESH
Matra-ERNO-SAAB-Hawker Siddeley Dynamics Aerospace Consortium

MET
Mission Elapsed Time

Meteor
Meteorological Satellite (Russian Federation)

Metro Ethernet
A network in which the customer interface is Ethernet based, and is typically offered in a metropolitan area versus over a wide area

METSTAT
Meteorological Satellite

mf OR MF
MF Medium Frequencies (Band 6)

MFC
Compelled Multifrequency Signaling

MFR
Manufacturer

MFS
Magnetic field strength

mg OR MG
mg Milligram

MGC
Multigroup Controller

mH
Millihenry

MHD
Magnetohydro-dynamics

MHz
Megahertz (one million cycles per second)

MIC
Microwave Integrated Circuit

MIFR
Master International Frequency Register (record of frequency assignments maintained by the IFRB) (ITU)

MIL-STD
Military Standards

MINIT
Minimum Interference Threshold

MIOS
Modular Input-Output System

MIP
Master Index Pulse

MIPR
Master Index Pulse Reference

MIPRG
Master Index Pulse Reference Generator

MIS
Management Integrated System

MJD
Modified Julian Date

MKS
Meters, Kilograms, and Seconds

ML
Mean Life

MLA
Microwave link Analyzer

MLI
Multilayer Insulation

MLO
Master Local Oscillator

MLS
Microwave Landing System

mm
Millimeter

MMH
Monomeghyl Hydrazine

mmHg
Millimeter of mercury

MMIC
Monolithic Microwave Integrated Circuit

MML
Man-Machine Language

MMS
Maritime Mobile Service

MMSS
Maritime Mobile Satellite Services

MMV
Multimission Modular Vehicle

MMW
Millimeter Wave

MNRU
Modulated Noise Reference Unit

MNVR
Maneuver

MOC
Management Observation and Conference Room

MOD
Microwave Oscillator Diode

Mod or MOD
Modulator

modem OR MODEM
Modulator

MOF
Maximum Observed Frequency

MOI
Minutes of Inertia

MOL or mol
MOL Manned Orbital Laboratory

MON
Monitoring Station

mono
Monostable

MOPT
Mean One-way Propagation Time

MORE
Maritime system (Russian Federation)

Morelos
Domestic satellite system (formerly Ilhuicahua - Mexico)

MOS
Metal Oxide semiconductor

MOSFET
Metal Oxide Semiconductor Field Effect Transistor

MOST
Metal-Oxide Semiconductor TransistorM

MOU
Memorandum Of Understanding

MPA
Medium Power Amplifier

MPEG
Moving Picture Experts Group

MPLS
Multi-Protocol Label Switching

MPLS Label
A short, fixed-length identifier that is used to determine the forwarding parameters of a packet on an MPLS network

MPM
Multilateral Planning Meeting

MPOD
Monopod

MPRS
Master Primary Reference Station

MPRT
Master Primary Reference Terminal

MPSK
Multiple-Phase Shift-Keying

MPU
Microprocessing Unit

MRB
Materials Review Board

MRIR
Medium Resolution Infrared Radiometer

MRR
Manufacturing Readiness Review

MRS
Minimum Residual Shutdown

ms OR mS
ms Millisecond

MSA
Metropolitan Statistical Area

MSAT
Canadian Mobile Satellite System

MSB
Most Significant Bit

MSC
Management Services Contract(or)

MSD
Most Significant Digit

MSED
Minimum Signal Element Duration

MSFN
Manned Space Flight Network

MSI
Medium-Scale Integration

MSK
Minimum Shift Keying

msl
Minimum Sea Level

MSM
Microwave Switch Matrix

MSR
Multifrequency Signal Register

MSS
Mobile Satellite Service

MSSF
Mate Scanner Stop Failure

MST
Mixed Simulation Tests

MSU
Maintenance Signal Unit

MSW
Microwave Spectrometer

MTBF
Mean Time Before/Between Failures

MTC
Main Trunk Circuit (WMO)

MTF
Modulation Transfer Function

MTP
Master/Motor Burst Time Plan

MTR
Motor

MTS
Message Telecommunications/Telephony Service

MTTF
Mean Time To Failure

MTTR
Mean Time To Restore/Repair

MTU
Magnetic Tape Unit

MU
Multi-Destination Unidirectional

MUF
Maximum Usable Frequency

MUL
Multi-use

MULT
Multiple

Multicast
A network technology for transmission of data files from a single source to multiple destinations efficiently, without duplicate use of bandwidth on the network. Contrast with Unicast

MUM
Multi-Unit Message

MUSE
Monitor of Ultraviolet Solar Energy

Mux OR MUX
Multiplexer

mV
Millivolt

MVBR
Multivibrator

MW or mW
MW Microwatt

MWA
Momentum Wheel Assembly

Mykotronx
(MYKO) A type of Ground Encryption Unit

n or N
n Nano (one-Billionth)

n-QAM
N-state Quadrature Amplitude Modulation

n.mi
Nautical mile

N/A
Not Applicable

N/I
Noise to Interference Ratio

nA
Nanoampere

NAB
National Association of Broadcasters (USA)

NACD
Network Autonomous Commanding Display

NACK
Negative Acknowledgement

NAM
National Association of Manufacturers (USA)

NAND
Type of logic circuit

NAS
National Academy of Sciences (USA)

NASA
National Aeronautics and Space Administration (USA)

NASC
National Aeronautics and Space Council (USA)

NASCOM
NASA Communications Network (USA)

NASDA
National Space Development Agency (Japan)

NAT/TFG
North Atlantic Traffic Forecasting Group

NAVSAT
Satellite Navigation Corporation Navy Satellite (US)

nb OR NB
Narrow Band

NBC
National Broadcasting Corporation (USA)

NBFM
Narrowband Frequency Modulation

NBR
No Burst Received

NBTR
Narrowband Tape Recorder

NC
Network Congestion/Concentrators

NCAP
Nonlinear Circuit Analysis Program

NCC
Network Control Center

NCM
Network Controller Module (Timeplex card)

NDB
Nondirectional Radio Beacon

NDES
Normal Digital Echo Suppressor

NDT
Nondestructive Test

NEA
Noise Equivalent Angle

NEC
Nippon Electric Company (Japan)

NESC
National Environmental Satellite Center (USA)

NESS
National Environment Satellite Service

Network Latency
Network Latency in a packet-switched network is the time it takes packets to traverse the network from source to destination.

nF OR NF
nF Nanofarad

NGO
Non-Governmental Organization

nH
Nanohenry

NHK
Nippon Hoso Kyokai (Japan Broadcasting Corporation)

Ni-Cd
Nickel Cadmium

Ni-H2
Nickel Hydrogen

NIC
Nearly Instantaneous Companding

NILS
Non-Intelsat Launch Support

NIMBUS
Meteorological Satellite (USA)

NIS
No Input Signal

NIST
National Institute of Standards and Technology (USA)

NL
New Line

NLR
Noise Loading Ratio

nm
Nanometer

NMC
National Meteorological Center (USA) (WMO)

NMCC
Network Management and Control Center

NMI
No Modular Input

NMOS
N-channel Metal Oxide Silicon

NMS
Network Management Signal

NNI
Network Node Interface

NOAA
National Oceanic and Atmospheric Administration (USA)

NOC
Network Operations Center

NOR
Not OR function

NORAD
North American Air Defense Command (USA)

NORDSAT
Broadcast television satellite system for Nordic countries (Norway)

NOS
No Output Signal

NOSFER
(New master system for the determination of reference equivalents)

Np OR NP
Np Neper

NPC
North Pacific Cable

NPN
Negative-Positive-Negative

NPNP
Negative-Positive-Negative-Positive

NPR
Noise Power Ratio

NPRC
Network Packet Recirculator/Concentrator

NPV
Net Present Value

NRDE
Non-Reference Diagnostic Equipment

NRMS
Network Reference and Monitoring Station

NRZ
Non-Return to Zero

NRZ-I
Non-Return-to-Zero-Inverted

NRZ-L
Non-Return to Zero-Low

NRZ-M
Non-Return to Zero Mark

NRZ-S
Non-Return to Zero-Space

NRZL
Non-Return to Zero Level

ns
Nanosecond (one-billionth)

NSA
National Security Agency (USA)

NSC
Network Switching Center

NSCS
Non-linear Satellite Channel Simulator

NSF
National Science Foundation (USA)

NSI
NASA Standard Initiator

NSL
Net Switching Loss

NSPC
National Sound Program Center

NSR
No Signal Received

NSSDC
National Space Science Data Center (USA)

NTC
National Television Center

NTI
Noise Transmission Impairment

NTIA
National Telecommunications and Information Administration (USA)

NTP
Network Terminating Point

NTS
Navigation Technology Satellite

NTSC
National Television System Committee

NTSC System
System of color television based on the recommendation of the NTSC using 525 lines and 60 fields with a video bandwidth of 4.2 MHz (US, Canada, Japan)

NTT
Nippon Telegraph and Telephone Public Corporation (Japan)

NTU
Network Terminating Unit

NU
Number Unobtainable

NUT
Nutation

nV
Nanovolt

NVR
Nonvolatile Residues

nW
Nanowatt

O/P
Output

O&M
Operation and Maintenance

OAO
Orbiting Astronomical Observatory

OAS
Orbit Adjust Subsystem

OAU
Organization of African Unity

OB
Outside Broadcast

OBA
Optical Barrel Assembly

OBE
Out-of-Band Emission

OBN
Out-of-Band Noise

OBWR
On-board Waveform Regenerator

OC-#
Optical Carrier

OCC
Operations Control Center (Intelsat)

OCE
On-Call Engineer

OCO
Oven Controlled Oscillator

OCW
Oscillator Control Word

OCXO
Oven-Controlled Crystal Oscillator

OD
Oceanographic Data Station

ODAS
Ocean Data Acquisition Systems (UNESCO)

ODBC
Open Database Connectivity (usually a driver) use support Microsoft ACCESS link and use SQL based d to tables.

ODD
Operator Distance Dialing

ODL
Orbital Design Life

OECD
Organization for Economic Cooperation and Development (UN)

OEM
Original Equipment Manufacturer

OES
Outgoing Echo Suppressor

OFHC
Oxygen-Free High Conductivity Copper

OFT
Orbital Flight Test

OGO
Orbiting Geophysical Observatory

OGR
Outgoing Repeater

OIRT
International Radio and Television Organization

OJT
On-the-Job Training

OLV
Oxidizer valve

OM
Orbital Mechanics

OMA
Operations Management Application

OMJ
Orthomode Junction

OML
Orbital Maneuver Life

OMP
Orbital Mechanics Processor

OMS
Orbital Maneuvering System

OMT
Orthomode Transducer

OMUX
Output Multiplexer

ONC
Ordinary National Certificate (UK)

OODBMS
Object Oriented Database Management System

OOS
Orbital Operations System

OP
Output Processor

opamp
Operational Amplifier

OPD
Operation Parameter Data

OPSK
Octal Phase Shift Kying

OPTT
Office des Postes et Telecommunications du Togo

OPTUS
Australian Telecommunications Carrier

OQPSK
Offset Quaternary Shift Keying

OR
Operations Research

ORACLE
Viewdata or teletext system similar to CEEFAX (BBC)

ORB
Obeyed Reference Burst

ORBIS
Orbiting Radio Beacon Ionospheric Satellite

ORION
Proposed Separate Satellite System

OSC
Oscillator

OSCAR
Amateur Radio Communications Satellite (USA and Australia)

OSEOS
Operational Synchronous Earth Observatory Satellite

OSI
Open System Interconnection

OSM
Miniaturized Rigid Coaxial Cable

OSO
Orbiting Solar Observatory (USA)

OSPK
Off Set Keyed Quadrature Phase Shift Keying

OSR
Optical Solar Reflector

OSV
Ocean Station Vessel (ICAO, WMO)

OTCI
Override TSO Corection Interval

OTE
Hellenic Telecommunications Organization, S.A.(Greece)

OTEC
Ocean Thermal Energy Conversion

OTI
Ibero-American Television Organization

OTLP
Zero Transmission Level Point

OTP
Office of Telecommunications Policy (USA)

OTS
Orbital Test Satellite

OTV
Orbital Transfer Vehicle

OU
Occasional Use

OUB
Occasional Use Bands

OVERVLTG
Over Voltage

OW
Order Wire

OWF
Optimum Working Frequency

OXD
Oxidizer

P OR p
P Microprocessor

P-P OR p-p OR p.p. OR pp
Peak-to-Peak

p.e.p. OR PEP
Peak Envelope Power

p.f.d OR PFD
Power Flux Density

P2MP
Point to multipoint

P2P
Point to point

PA or pA
PA Power Amplifier

PABX
Private Automatic Branch Exchange

PAC
Platform Azimuth Control

Packet
A formatted block of data that is routed between an origin and a destination on a network.

Packet Loss
A type of error on a digital network that occurs when one or more packets of data traveling across a network fail to reach their destination.

PAD
Packet Assembly and Disassembly

PADS
Development Laboratories

PAGEOS
Passive Geodetic Earth-Orbiting Satellite (NASA - USA)

PAL
Phase Alternation Line (TV standard)

PAL-M
PAL System using NTSC Parameters

PALAPA
Domestic satellite system (Indonesia)

PAM
Payload Assist Module

PAM-D
Payload Assist Module D

PAMA
Pulse Address Multiple Access

PAML
Program Authorized Materials List

PANA
Pan-African News Agency

PANAFTEL
Pan-African Telecommunication Network

PanAmSat
Alpha Lyracom Space Communications Satellite Network (USA)

PANDA
Pivot-Assisted Nutation Damping Assembly

PAPM
Pulse Amplitude and Phase Modulation

Par OR PAR
Par OR PAR Parity

Paramp
Parametric amplifier

PAT
Pending Alarms Control Table

PATU
Pan-African Telecommunications Union

PAX
Private Automatic Exchange

PBC
Program Booking Center

PBER
Pseudo Bit Error Rate (pseudo BER)

PBK
Playback Mode

PBM
Perigee Boost Motor

PBS
Public Broadcasting System (USA)

PBX
Private Branch Exchange

PC or pc
PC Personal Computer

PCA
Polar Cap Absorption

pcb OR PCB
Printed Circuit Board

PCE
Power Conditioning Electronics

PCI
Pattern Correspondence Index

PCM
Payload Change Out Room

PCMID
Pulse Command ID

PCU
Power Control Unit

PDA
Predetermined Arc

PDC
Platform Despin Controller

pdf OR p.d.f.
Probability Density Function

PDH
Plesiochronous Digital Hierarchy

PDL
Program Design Language

PDM
(syn.: pulse width modulation)

PDN
Public Data Network

PDR
Preliminary Design Review

PDS
Planned Domestic Services

PDTS
PCM/DSI Test Set

PDUS
Primary Data Receiving Station (Meteosat)

PE
Pictorial Element

PEC
(Marconi SCG)

PEM
Proto Environmental Model

PERT
Project Evaluation and Review Technique

PERUMTEL
Perusahaan Ummum Telekonunikasi (Indonesia)

PES
Post-Ejection Sequencer

PESC
Telephone Engineering Service Circuit

pF OR PF
pF Picofarad (Unit of electrical capacitance)

PFB
Provisional Frequency Board

PFIX
Power Failure Interrupt

PFM
Protoflight Model

PFO
Pilot Frequency Oscillator

PG
Permanent Glow

PGM
Program

PGP
Pretty Good Privacy

PH
Packet Handler

Phebus
European Experimental Broadcast Television Satellite (also H-Sat)

PHILCOMSAT
Communications Satellite Corporation (Philippines)

Pico
A trillionth

PID
Parameter Identification Directory

PIL
Pilot

PIM
Passive Intermodulation

PIN
Parameter Identification Number / Name

PIP
Payload Integration Plan

PIRC
Pacific and Indian Ocean Restoration Committee

PIU
Payload Interface Unit

PIV
Peak Inverse Voltage

PKM
Perigee Kick Motor

PKO
Project Kick-Off meeting

PL
Parts List

PLD
Phase-Locked Demodulator

PLE
Plesetsk Launch Complex (Russian Federation)

PLL
Phase-Locked Loop

PLS
Phase-Lock system

PLU
Phase Lock Unit

PM
Permanent Magnet

PMA
Permanent Management Arrangements

PMB
Proto Main Body

PMBX
Private Manual Branch Exchange

PMD
Propellant Management Device

PMF
Perigee Motor Firing

PMO
Project Management Office

PMOS
P-channel MOS

PMR
Pressure Modulated Radiometer

PMS
Picturephone Meeting Service

PMU
Propellant Management Unit

PN
Positive-Negative junction

PNM
Pulse Number Modulation

PNP
Positive-Negative-Positive junction

PNPN
Positive-Negative-Positive-Negative

PNS
Primary North-South Stationkeeping

POCA
Point of Closest Approach

POGO
Polar Orbiting Geophysical Observatory

POL
Polarization

Polang
Polarization Angle

PoP
Point of Presence

POR
Pacific Ocean Region

POS
Positioning

pot OR POT
Potentiometer

POTOK
Satellite Network (Russian Federation)

PP
Patch Panel

PPA
Platform Pointing Angle

PPF
Payload Processing Facility

PPI
Plan Position Indicator

ppm OR PPM
PPM Parts Per Million

PPS
Pulses Per Second

PPU
Power Processor Unit

PQM
Proto Qualification Model

PR
Preemptible

PRB
Primary Reference Burst

PRBS
Primary Reference Burst Sequence

Preamp
Preamplifier

PRESTEL
Tradename for the United Kingdom Post Office Corporation's viewdata or telex service (UK)

PRF
Pulse Repetition Frequency

PRFD
Pulse Recurrence Frequency Discrimination

PRI
Primary

PRN
Pseudo-Random Noise

PROC
Processor

Progress
Modified Automatic Soyuz Cargo Spacecraft (Russian Federation)

PROM
Programmable Read Only Memory - silicon chips that are "burnt" according to NSA's KI-23 algorithm. These chips, sometimes referred to as "PROMs" or "Keys", consist of 24 six (6) bit words. Each word is used to select a certain bit in the 63-bit shift register contained within an encryption/decryption device. These chips are loaded into a ground encryption unit (GEU) and onto a S/C decryption unit. When a GEU is instructed to select a location, and then passed a string of 63 bits, the "key" loaded in this location, will cause the 63 bits in this string to be uniquely shifted to different positions.

PROP
Propulsion

PRPM
Primary Power Monitor

PRR
Pulse Repetition Rate

PRT
Primary Reference Terminal

ps OR PS
ps Picosecond

PSC
Perigee Stage Cradle

PSD
Performance Start Date

PSDU
Perigee Stage Driver Unit

PSI OR psi
PSI Paid Service Indication

psia
Pounds Per Square Inch Absolute

psid
Pounds Per Square Inch differential

psig OR PSIG
Pounds Per Square Inch Gauge

PSK
Phase Shift Keying

PSM
Power System Monitor

PSN
Primary North/South Stationkeeping

PSSC
Public Service Satellite Consortium (USA)

PSTN
Public Switched Telephone Network

PSU
Power Supply Unit

PTAT
Private Transatlantic Cable

PTC
Pacific Telecommunications Council

PTD
Proceed-To-Dial (signal)

PTDS
Program Track Data Switch

PTLU
Pre-Transmission Line-Up

PTM
Pulse Time Modulation

PTS
PCM Telemetry Switch

PTT
Post, Telegraph, Telephone (general designation)

PULSAR
Pulsed Sequential Access Relay

PUT
Programmable Uni-junction Transistor

PV
Present Value

PVA
Perigee Velocity Augmentation

PVC
Polyvinyl Chloride

pW
Picowatt

PWM
Pulse Width Modulation

PWMP
Psophometrically Weighted Mean Power

pWp
Picowatt psophometrically weighted

pWp0
Picowatt Psophometrically weighted measured at a point of zero transmission level (0TLP)

PWR
Power

Q
Quality Factor

QA
Quality Assurance

QAM
Quad Asynchronous I/O Module

QAM-PAM
Quadrature Amplitude Modulation-Pulse Amplitude Modulation

QASK
Quadrature Amplitude Shift Keying

QAT
Quick Roll Estimate Attitude Trim

QC
Quality Control

QDU
Quantization Distortion Unit

QM
Qualification Model

QPRS
Quadrature Partial-Response System

QPSK
Quaternary Phase Shift Keying

QPSK/FDMA
Quaternary Phase Shift Keying/ Frequency Division Multiple Access

QRP
Low-power amateur radio

QSM
Quad Synchronous Module

QSS
Quasar (Quasi-Stellar Radio Source)

QTY
Quantity

QVM
Quadrature

R
Degree Rankine

R&D
Research and Development

R&QA
Reliability and Quality Assurance

RA NODE
Right Ascension of Ascending Node

Ra or RA
Ra Radium (chemical symbol)

RAC
Repeat Automated Command

Rad OR RAD
Radian

RADA
Random Access Discrete Address

RADAR
Radio Receiving and Ranging

RADTR
Radiator

RAF
Rate Adjustment Factor

RAG
Request Handling and Assignment Generation

RAM
Random Access Memory

RAMS
Random Access Measuring System

RARC
Regional Administrative Radio Conference

RAS
Remote Analysis System

RASCOM
Regional African Satellite Communications System

RB
Reference Burst

RBD
Reference Burst Distribution

RBID
Reference Burst Identification

RBOC
Regional Bell Operating Company (USA)

RBU
Receive Baseband Unit

RBV
Remote Beam Vidicom

RBW
Reverse Band Working

RC
Remote Control

RCA
Radio Corporation of America (USA)

RCC
Rescue Coordination Center

RCEC
Repayment of Capital/Excess Compensation Account

RCO
Restoration Control Office

RCP
Receive Channel Processing Function

RCS
Reaction Control (Sub)System

RCT
Reaction Control Thruster

RCTL
Resistor-Capacitor-Transistor Logic

RCTP
Retransmitted Condensed Burst Time Plan

RCV
Reveive

RDARA
Regional and Domestic Air Route Area

RDB
Rate Distortion Bound

RDF
Repeater Distribution Frame

RDG
Receive Data Gate

RDM
Read-only Memory

RDSS
Radio Determination Satellite Service

RDU
Remote Decoder/Distribution Unit

RDUR
RCS Duration

RE
Earth Radii

REA
Reaction Engine Assembly

RECON
Battery Reconditioning

RED
Redundant

REJ
Receiving Reject

REL
Relative

RELP
Residual Excited Linear Processor

RELRATE
Relative Rate

REOR
Reorientation

REP
Repetition

RESTEC
Remote Sensing Technology Center (Japan)

RET
Reliable Earth Terminal

RF
Radio Frequency

RFC
Request For Change

RFI
Radio Frequency Interference

RFP
Request For Proposal

RFQ
Request For Quotation

RFS
Ready For Service

RG
Guard Release

RGB
Red-Green-Blue

RGM
Release Guard Message

RHCP
Right Hand Circular Polarization

RI
Repeat Indication

RIF
Receive IF

RIM
Receiver Intermodulation

RIP
Ring Interface Processor

RIS
Retransmission Identity/Indication Signal

RJE
Remote Job Entry

RL
Return Loss

RLO
Restoration Liaison Officer

RLSF
Release Failure

RLY
Relay

RMA
Random Multiple Access

RMAC
Remote Monitoring and Control

RMBAFN
Reconfigurable Multibeam Antenna Feed Network

RMC
Regional Meteorological Center (WMO)

RMI
Route Monitoring Information

RMS OR rms
RMS Remote Manipulator System

RMTE
Remote

RN
Radio Networking System

RNG
Ranging

RNI
Ready for Network Integration

RO
Receive Only

ROI
Return on Investment

ROM
Read Only Memory

ROP
Reference Terminal Operational Parameters

ROSAT
Roentgen Satellite (Germany)

ROTV
Receive-Only television

RPLY
Reply

rpm OR RPM
Revolutions Per Minute

RPOA
Recognized Private Operating Agency

RPOE
Recognized Private Operating Entity

RPS OR rps
RPS Relative Performance Score

RPU
Ranging Processing Unit

RQ
Repetition of Information

RR
Radio Regulations

RR/u
Revenue Requirements per Unit

RRE
Receiving Reference Equivalent

RRL
Radio Research Laboratories (Japan)

RRM
Relative Rate Mode

RRS
Retransmission Request Signal

RRT
Relative Rate Fault Detection and Recovery

RS
Reed Solomon (block) encoder/decoder Record Separator

RSA
Revenue and Signatory Accounting

RSAN
Remote Spectrum Analyzer Network

RSD
Radial Spin Down

RSE
Register Signaling Equipment

RSO
Redundancy Switchover

RSP
Receive Shift Pulse

RSR
Revenue System Redevelopment

rss OR RSS
Root Sum Squares

RSSD
Reference Station Status Display

RST
Reference State Table

RSTN
Regional Seismic Test Network

RSU
Radial Spin Up

RT
Radiotelephone

RTCTP
Reference Terminal Condensed Burst Time Plan

RTE
Real Time Executive

RTE-A
HP 1000 Operating System

RTE/TSM
TDMA Reference and Monitor Station Equipment

RTEP
Reference Terminal Equipment Processor

RTF
Radiotelephony

RTG
Radio-isotope Thermoelectric Generator

RTH
Regional Telecommunication Hub

RTI
Real Time Interrupt

RTL
Resistor-Transistor Logic

RTM
Redundant Telemetry Modules

RTNR
Ring Tone No Reply

RTP
Real Time Peripheral

RTT
Ratioteletype

RTU
Remote Telemetry Unit

RUD
Receive Channel Status Update and Overload Canal Decoding Process

RURAX
Rural Automatic Exchange

RX OR Rx
Receive/Receiver

Rz OR RZ
Return to Zero

S or s
S Distance along a path (phys., chem.) Specific Entropy

S-meter
Signal-Strength meter

S/C
Spacecraft

S/C Key
The term used to indicate a unique location within a decryption unit on-board a S/C

S/EOS
Standard Earth Observation Satellite

S/I
Signal-to-Interference Ratio

S/N
Signal-to-Noise Ratio

S/Q
Signal Quality Value

S+DX
Speech+Duplex (Simultaneous Speech and Telegraphy in a Voice Channel)

SABM
Set Asynchronous Balanced Mode command

SAC
Spin Axis Control

SAD
Space Antennae Diversity

SADA
Solar Array Drive Assembly

SADE
Solar Array Drive Electronics

SAGR
Supergroup Automatic Gain Regulator

SAIL
Shuttle Avionics Integration Laboratory (NASA - USA)

SAM
Selective Assignment Message

SAMOS
Air Force Reconnaissance Satellite (USA)

SAMS
Stratospheric and Mesospheric Sounder

SAMSARS
Satellite-Based Maritime Search and Rescue System

SAR
Search and Rescue

SARIT
Satellite Network (Italy)

SARSAT
Search and Rescue Satellite (US, Russian Federation, France and Canada)

SAS
Small Astronomical Satellite

SATCOM
Domestic satellite network (Owned by RCA American Communications, Inc. - USA)

SAW
Surface Acoustic Wave

SAX
Small Automatic Exchange

SB
Simultaneous Broadcast

SBPC
Single Burst per Transmitter/Transponder

SBTP
Secondary Burst Time Plan

SC
Service Channel or Satellite Channel

SCA
Small Communications Antenna

SCATHA
Spacecraft Charging at High Altitudes Scientific Satellite (USA)

SCC
Satellite Control Center (Intelsat)

SCD
Service Commencement Date

SCE
Spacecraft Control Electronics

SCF
Satellite/Spacecraft Control Facility

SCFM
Sub-carrier Frequency Modulation

SCG
Signal/Synchronous Command Generator

SCH
Seizures per Circuit per Hour

SCIM
Speech Communications Index Meter

SCMID
Serial Command ID

SCN
Software Change Notice

SCNA
Sudden Cosmic Noise Absorption

Scope
Oscilloscope

SCOR
Scientific Committee On Ocean Research

SCP
Satellite Channel Processing Procedure

SCPC
PCM/PSK Telecommunications Equipment

SCPC/CFM
Single Channel Per Carrier/Companded Frequency Modulation

SCPDM
Suppressed Clock Pulse Duration Modulation

SCR
Selective Chopper Radiometer

SCS
Silicon-Controlled Switch

SCTO
Stalled Call Timed Out

SCU
System Control Signal Unit

SCUC
Satellite Communications Users Conference

SD
Single Destinational

SD-SDI
Serial Digital Interface

SDCV
Spatially-dedicated Continuously-visible

SDF
Supergroup Distribution Frame

SDH
Synchronous Digital Hierarchy

SDI
Strategic Defense Initiative (USA)

SDL
Specification and Description Language

SDMA
Space Domain/Division Multiple Access

SDNTX
Selective Do Not Transmit

SDP
Solar Drum Positioner

SDRO
Selected Data Retrieval Output

SDS
Satellite Diagnostic Subsystem

SDU
Spun Driver Unit

SEA
Sudden Enhancement of Atmospherics

SEC
American Security Carrier

SED
Service End Date

SEER
Secondary Electron Emission Ratio

SEG
System Engineering Group

SEL
Selected

SELCAL
Selective Call/Calling

SEM
Scanning Electron Microscope

SEMS
Space Environment Monitor Subsystems

SEN
SENSE command

SEOS
Synchronous Earth Observation Satellite

SEQ
Sequence

Service Availability
The percentage of time within the total time for a service ordered by a customer during which the service is available to successfully transfer customer content

SES
Severely Errored Seconds

SET
European Telecommunications Working Group of the CEPT

SETAB
(Working standard with subscriber's equipment)

SETED
(Working standard with an electrodynamic microphone and receiver

SEU
Single Event Upset

SFD
Saturation Flux Density

SFERT
Master Telephone Transmission Reference System

SFOF
Space Flight Operation Facility

SG
Super Group (CCIR/CCITT)

SGCS
Satellite Ground Control System (Intelsat)

SGDF
Supergroup Distribution Frame

SGP
Simplfied General Perturbation

SHA
Sidereal Hour Angle

SHAR
Sriharikota Island Launch Complex (India)

SHE
Spacecraft Handling Equipment

SHF
Super High Frequency 3,000 - 30,000 MHz Shuttle Launcher (NASA - USA)

SI
Speech Interpolation

SICC
Spanish International Communications Corporation (USA)

SICL
HP's Standard Instrument Control Library

SID
Sudden Ionospheric Disturbance

SIDEREAL
Sidereal clock time relative to orbit node

SIDM
Single Integration Delta Modulation

SIG
Senior Interagency Group

SIM
Simulator

SIMP
Satellite Interface Message Processor

SIR
Selected for Internal Reference

SIRIO
Experimental Satellite Network (Italy)

SIT
Static Induction Transistor

SITC
Satellite International Television Center

SITE
Satellite Instructional TV Experiment

SIU
Signaling Interface Unit

SIV
Solar and Interplanetary Variability

SLA
Service Level Agreement

SLL
Satellite Line Link

SLMS
Selective Level Measurement Set

SLOHA
Slotted ALOHA

SLS
Side Lobe Suppression

SLT
Satellite Local Time

SMA
Search Mode Acquisition

SMDU
Stepper Motor Drive Unit

SME
Solar Mesosphere Explorer (NASA Satellite - USA)

SMM
Solar Maximum Mission (NASA Satellite - USA)

SMS
Shuttle Mission Simulator

SMY
Solar Maximum Year

SNDTX
Selective Do Not Transmit code

SNF
System Noise Figure

SNG
Satellite Newsgathering

SNL
SYNCH Loss

SNR
Signal-to-Noise Ratio

SNT
System Noise Temperature

SO
Shift-Out

SOC
Satellite Operations Complex

SOD
Satellite Operations Department

SOE
Sequence of Events

SOF
Satisfactory Operation Factor

SOH
Start of Heading

SOI
Silicon-On-Isolator

SOLAS
Safety Of Life At Sea

SOM
Space Oblique Mercator

SOP
Single Ocean Payload

SORF
Start of Receive Frame

SORMF
Start of Receive Multiframe

SOS
Silicon-On-Sapphire

SOTF
Start Of Transmit Frame

SOTMF
Start Of Transmit Multiframe

SOW
Statement of Work

Soyuz
Two-Man Spacecraft (Russian Federation)

SPACENET
Domestic satellite network (Owned by GTE - USA)

SPADE
SCPC PCM multiple Access Demand assigned Equipment

SPAS
Shuttle Payload Satellite

SPC
Stored Program Control

SPD
Synchronous Phase UW Detection

SPDT
Single Pole Double Throw

SPE
Signal Processing Equipment

SPEC
South Pacific Economic Cooperative

SPELDA
Dual-launch system for heavy geostationary payloads, used by Ariane

SPF
Single Point Failure

SPI
Software Productivity Improvement

SPINE
Space Information Network Experiment (ESA)

SPL
Signal Processing Modem

SPM
Signal Processing Modem

SPN
Spin

SPOT
Earth Observation Satellite System (France)

SPR
Software Problem Report

SPS
Solar Powered Satellite

SPST
Single Pole/Single Throw

SPT
System Performance Test

Sputnik
Experimental satellite for manned space flights (Russian Federation)

SQL
Structured Query Language

SQRX
Square Axis Positioner

SR
Scanning Radiometer

SRA
Slip Ring Assembly

SRAEN
Reference system for the determination of articulation reference equivalents

SRARQ
Selective Repeat-Automatic Repeat Request

SRATS
Solar Radiation and Thermospheric Structure Satellite (Japan)

SRB
Secondary Reference Burst

SRC
Source

SRD
Step Recovery Diode

SRE
Sending Reference Equivalent

SRF
Service Request Flag

SRIP
Supplemental Retirement Income Plan

SRL
Stability Return Loss

SRM
Solid Rocket Motor

SRO
Synthesizer Reference Oscillator

SRP
Signal Reference Point

SRR
Shipment Readiness Review

SRS
Secondary Reference Station

SRT
Secondary Reference Terminal

SRTS
Supporting RTE and TSM System

SS
Satellite Switching

SS-TDMA OR SS/TDMA
Satellite-Switched Time Division Multiple Access

SS/L
Space Systems/Loral

SSB
Single Sideband (AM)

SSB-SC-AM
Single Sideband Suppressed Carrier Amplitude

SSB-SC-ASK
Single Sideband Suppressed Carrier Amplitude Shift Keyed

SSB-SC-PAM
Single Sideband Suppressed Carrier Pulse Amplitude Modulation

SSBTP
Satellite Switching Burst Time Plan

SSC
Satellite Situation Center

SSCTP
Satellite Switching Condensed Time Plan

SSD
Service Start Date

SSE
Space Segment Engineering

SSES
Space Segment Payload Engineers

SSFC
Sequential Single Frequency Code

SSI
Small-Scale Integration

SSLO
Solid State Local Oscillator

SSM
Satellite System Monitor

SSMA
Spread Spectrum Multiple Access

SSME
Space Shuttle Main Engine

SSMG
Satellite System Monitoring Group

SSMTP
Satellite Switching Master Time Plan

SSO
Simultaneous Sun Outage

SSOG
Satellite Systems Operations Guide (Intelsat)

SSOP
Satellite System Operations Plan

SSP
Sensor Suite Positioner Sub-Satellite Point

SSPA
Solid State Power Amplifier

SSPS
Satellite Solar Power Station

SSR
Steady State Reception

SSRA
Spread Spectrum Random Access

SSRTE
Satellite Switching Reference Terminal Equipment

SSSF
Self-Scanner Stop Failure

SST
Satellite-to-Satellite Tracking

SSTDMA
Satellite Switched Time Division Multiple Access

SSTM
Station to Station Traffic Matrix

SSTP
Switch State Time Plan

SSTV
Slow Scan Television

SSU
Secondary Sampling Unit

SSUS
Solid Spinning Upper Stage

SSV
Switch State Verification

ST
"End Pulsing" Command (CCITT format)

STA
Structural Test Article

STAR
Satellite Telecommunications with Automatic Routing (Simple form of SPADE system)

STAT
Status

STATSIONAR
Communications Satellite for Geostationary Orbit Operation (Russian Federation)

STBY
Standby

STC
Switching and Testing Center

STCC
Spacecraft Technical Control Center

STD
Subscriber Trunk Dialing

STDN
Space Tracking and Data Network

STE
Spacecraft Test Equipment

STELLA
Satellite Transmission Experiment Linking Laboratories (ESA)

STEP
Stepper

STETS
Solar Terrestrial Energy Transfer Studies

STIPS
Study of Traveling Interplanetary Phenomenon

STM
Structural Test/Thermal Model

STOM
Spade Terminal Operator's Manual

STOW
Stowed

STOX
Speech plus Duplex (speech and telegraphy in voice channel)

STP
Signal Transfer Point

STR
Strength

STRATS
Solar Radiation and Thermospheric Satellite (Japan)

Streaming
A method for delivering video or other content over a telecommunications network in a continuous flow

STRIP
Satellite Transmission Impairment Program

STRT
Start

STS
Space Transportation System (operated by NASA - USA)(the Shuttle)

STSK
Scandinavian Committee for Satellite Telecommunications

STX
Start of Text

SU
Signal Unit

SUB
Substitute Character

SUPARCOT
Space and Upper Atmosphere Research Commission (Pakistan)

SURVSATCOM
Survivable Communications Satellite

SVC
Secure Voice Communications Service / System

SVM
Space Vehicle Motor

SW
Short-Wave (radio)

SWE
Spherical Wave Expansion

SWF
Short Wave Fadeout

SWG
Standard Wire Gauge

SWI
Special World Interval

SWIFT
Society for Worldwide Interbank Financial Telecommunications

SWL
Short-Wave Listener

SWOF
Switchover Operation Failure

SWR
Standing Wave Ratio

SYMCOSAT
Consortium for Symphony Satellite

Symphonie
Experimental Satellite System (France/Germany)

SYN
Synthesizer

SYNCH
Syncronize/Synchronizer

SYNCOM
Early Geostationary Satellite (USA)

SYNCOM IV
Experimental Satellite Designed by Hughes Aircraft for STS Launch (prototype for operational satellites for 1980's - USA)

SYSGEN
System Generation

SYU
Synchronous Signal Unit

t OR T
t Metric ton

T/R OR TR
Transmit/Receive

T/V
Thermal Vacuum

T&C
Telemetry and Command

T&EC
Tests and Evaluation Center

TA
Terminal Acquisition

TAAPM
Two-Axis Antenna Positioning Mechanism

TACSAT
Tactical Satellite (USA)

TAM
Total Assignment Message

TANC
Thrust Actuated Nutation Damping Control

TARS
Turn Around Ranging Station

TAS
Terminal Acquisition Support

TASI
Time Assignment Speech Interpolation

TASO
Television Advisory Standards Organization

TASS
Terminal Acquisition and Synchronization Support

TAT
Transatlantic Telephone (USA/Europe) Cable

TAW
Terminal Acquisition Window

TB
Traffic Burst

TBBF
Top Baseband Frequency

TBD
To be determined/defined/developed/done

TBM
Traffic Burst Monitor

TBMP
Traffic Burst Monitor Procedure

TBn
Traffic Burst No. n

TBTP
TSM Burst Time Plan

TBU
Transmit Baseband Unit

TC
Temperature Coefficient

TC&R
Telemetry, Command, and Ranging

TCA
Thrust Chamber Assembly

TCAR
TDMA Channel Assignment Record

TCC
Telephone Coordinating Circuit

TCE
Telemetry and Command Equipment

TCEU
Telemetry and Command Extension Unit

TCH
Transparent Circuit Handler

TCI
TSO Correction Interval

TCM
Trajectory Correction Maneuvers

TCP
Thruster Control Processor

TCRG
Trunk Circuit Relay Group

TCS
Technical Communications Support

TCTP
Test Abridged CTP

TCTS
Trans-Canada Telephone System (Canada)

TCU
Thruster Control Unit

TCW
Telemetry Control Word

TCXO
Temperature-Compensated/Controlled Crystal Oscillator

TD-PSK
Time-Differential Phase-Shift Keyed System

TDA
Terminal/Tunnel Diode Amplifier

TDB
Traffic Data Base

TDC
Telegraphy Data Channel

TDF
Broadcasting Satellite Network (France)

TDG
Transmit Data Gate

TDHS
Test Data Handling System

TDL
Tapped Delay Line

TDM
Time Division Multiplex

TDMA
Time Division Multiple Access

TDMA/DNI
Time Division Multiple Access without Digital Speech Interpolation

TDMA/DSI
Time Division Multiple Access with Digital Speech Interpolation

TDMS
Telegraph Distortion Measuring Set

TDP
Telemetry and Display Processors

TDR
Time Domain Reflectometer

TDRS
Tracking and Data Relay Satellite

TDRSS
Tracking and Data Relay Satellite System

TDS
Tracking and Data Acquisition Station

TDU
TDMA Diagnostic Unit

TE
Threshold Extension

TEAGEN
Telemetry Event and Alarm Generation Module

TEC
Total Electron Content

TECD
TDMA Equipment Configuration Data

TED
Telemetry Event Detection

TEL
Telephone

TELCOR
Instituto Nicaraguense de Telecomunicaciones y Correos (Nicaragua)

TELE-X
Experimental Satellite Network (Sweden)

TELECOM
Empresa Nacional de Telecomunicaciones de Colombia'

TELEDIREKTORATE
Telecommunications Administration (Norway)

TELESAT
Domestic Satellite (Canada)

TELESPAZIO
Societa per azioni per le comunicazioni spaziali (Italy)

TELEX
Switched Automatic Telegraph Subscriber Network

TEM
Transverse electric and magnetic mode

TEMP
Temperature

TERA OR TERRA
One trillion

TERLS
Thumba Equatorial Rocket Launching Center (India)

TERM
Termination

TESC
TDMA Engineering Service Circuits

TETTO
Toroidal Beam Telemetry Antenna

TEXTEL
Trinidad and Tobago External Telecommunications Co., Ltd.

TFA
Transmit Frame Acquisition

TFAS
Terminal Frame Acquisition and Synchronization

TFC
Traffic

TFD
Telemetry Field Descriptor

TFE
Thuster Firing Electronics

TFG
Transmit Frame Generation

TFG-DM
Telemetry Format Generator - Dwell Mode

TFG-NM
Telemetry Format Generator - Normal Mode

TFM
Tamed frequency modulation

TFR
Theoretical Final Route

TFS
Transmit Frame Synchronization

TFT
Thin Film Transistor

TFU
Timing and Frequency Unit

TG OR Tg
TG Task Group (CCIR)

TGF
Through Group Filter

TH
Transponder/Time Hopping

THD
Total Harmonic Distortion

THR
Thruster

TID
Travelling Ionospheric Disturbance

TIE
Trunk Interface Equipment

TIFF
Tagged Image File Format (computer graphics)

TIM
TDMA/Terrestrial Interface Module

TIP
Tracking Impact Prediction (DUS Satellite)

TIROS
Meteorological Satellite (USA)

TIRS
Thermal Infrared Scanner

TIU
Terrestrial Interface Unit

TIUPIL
Typical Information Use Per Individual

TLM
Telemetry

TLP
Transmission Level Point

TM
Telemetered

TM/TC
Telemetry/telecommand

TMATV
Time multiplex analog television

TMF
Test and maintenance facility

TMN
Network

TNIP
Terrestrial Network Interface Processor

TNS
TDMA network simulator

TOA
Time Of Arrival

TOC
Table of Coincidences

TOCC
Technical and Operational Control Center (UK)

TOD
Time of Date

TOIRS
Transfer Orbit Infrared Earth Sensor

TOJ
Telecommunications of Jamaica Ltd.

TOPS
Telemetry Operations

TOR
Telegraph on Radio

TORQ
Torque

TOS
Time Ordered System

TOSSA
Transfer Orbit Sun Sensor Assembly

TOT
Time of Transmission

TOVS
TIROS Operational Vertical Sounder

TP
Telemetry Processor

TPC
Transpacific Cable

TPD
Time Pulse Delay

TPL
Transmission Point Level

TPOD
Tripod

TPP
Telecommunication Preparatory Program

TPS
Therman Protection System

TPT
Transmission Path Translator

TRAD
Directional Telemetry Antenna

TRF
Tuned Radio Frequency

triac
Triode AC semiconductor switch

TRM
Transmit-Receive Module

TRMA
Time Randon Multiple Access

TRMS
TDMA reference and monitoring station

TRR
Test readiness review

TRT
Timing and Reference Transponder

TRU
Transponder Right of Use

TS
Telegraph Service (CCITT)

TSC
Technical Services Contractor

TSCM
Terminal Service Channel Monitor

TSDE
Time Source Digital Electronics

TSDS
Terminal Stripchart Display System

TSESC
Telegraph Engineering Service Circuit

TSF
Through Supergroup Filter

TSGF
Through Supergroup Filter

TSM
TDMA System Monitor

TSO
Time sharing option

TSP
Transmit Shift Pulse

TSPS
Traffic Service Positions System

TSS
Terminal Synchronization Support

TSSD
TDMA system status display

TSU
Tandem/Test/Telephone/Terminating Signal Unit

TT&C
Tracking Telemetry and Command

TT&R
Tracking, Telemetry and Ranging

TTB
Trunk Test Buffer

TTC OR TT&C
Tracking, Telemetry and Command

TTC&M
Tracking, Telemetry, Command and Monitoring

TTC&R
Tracking, Telemetry, Command and Ranging

TTF
Test Time Frame

TTG
Transmit Timing Generator

TTK
Time-To-Knee test

TTL, T 2L
Transistor-Transistor Logic

TTP
Trunk Test Panel

TTPB
Trunk Test Panel Buffer

TTS
TDMA/Traffic Terminal Simulator

TTY
Telegraphic teletype/teleprinter/teletypewriter (order wire)

TU
Transmission Unit

TURS
Timing unit redundancy selector

TUU
Transponder for Unrestricted Use

TV
Television (video and assigned audio)

TV-SAT
Satellite Network (Germany)

TV/FM
Frequency modulation television with associated audio FM-subcarrier

TVC
Thrust Vector Control

TVEC
Total Vertical Electron Content

TVI
Television Interference

TVRO
Television receive only Terminal

TVSC
Television Service Center

TVT
Television Typewriter

TW
Travelling wave

TWEB
Transcribed Weather Broadcast

TWERLE
Tropical Wind, Energy Conversion, Reference Level Experiment

TWT
Travelling Wave Tube

TWTA
Travelling Wave Tube Amplifier

TWX
Teletypewriter Exchange Service

TX
Transmitter

TX/RCU
Transmit/Receive Control Unit

U/C
Up-Converter

U/D
Up/down chain

UA
Unnumbered Acknowledge Response

UAMPT
African and Malagasy Postal and Telecommunications Union

UAPT
African Postal and Telecommunications Union

UARS
Upper Atmospheric Research Satellite

UART
Universal Asynchronous Receiver/Transmitter

UARTO
United Arab Republic Telecommunication Organization

UAS
Unified Antenna Structure

UAX
Unit Automatic Exchange

UBK
Unblock

UC
Unit Call

UDC
Universal Data Classification

UDMH
Unsymmetrical dimethyl Hydrozine

UDTS
Universal Data Transfer Service

UER
Union Europeenne Radiodiffusion (European Broadcasting Union)

UET
Unattended earth terminal

UFB
Unfit for Broadcast

UFT
Voice Frequency (VF) Telegraphy

UHF
Ultra-High Frequencies (Band 9; 300-3000 MHz)

UITP
International Union of Public Transport

UJT
Unijunction Transistor

ULK
Unlock

ULPC
Uplink power control system

UN
United Nations

UNCTAD
United Nations Conference on Trade and Development (UN)

UNDP
Development Program (UN)

UNDRO
Office of Disaster Relief Coordinator (UN)

UNEP
Environment Program (UN)

UNESCO
Educational, Scientific and Cultural Organization (UN)

UNI
User-network interface

Unicast
Data transmission from a single source to a single destination. Contrast with Multicast.

UNICODEC
Universal Coder/Decoder (TV Service)

UNIPEDE
(International union of Producers and Distributors of Electric Energy)

UNITAR
Institute for Training and Research (UN)

UNL
Unlatched

UPC
Universal Product Code

UPLS
Up-Front-Lump-Sum

UPS
Uninterruptible Power Supply

URM
Universal Restoration Manual

URSI
(International Union of Radio Science)

URTNA
(Union of National Radio and Television Organizations of Africa)

US
Unit Separator

USAID
United States Agency for International Development (USA)

USASAT
Generic name given to USA satellite networks

USB
Upper Side Band

USGS
United States Geological Survey (USA)

USISC
International Service Carriers (USA)

USS
Uplink Selector Switch

UST
"Unblock SPADE Terminal" command

UT
Universal Time

UTC
Universal Coordinated Time

UTCA
Unconstrained Terminal Control Assignment

uW OR UW
uW Microwatt

UWER
Unique word error rate

UWL
Unique word loss

UWP
Unique word processor

UZrH
Uranium zirconium hydride reactor

V OR v
V Delta velocity

V/D
Voice/Data

V/F
Voltage-to-Frequency

V1
Critical Speed

VA
Volt Ampere

VAB
Vehicle Assembly Building (Kennedy Space Center, Florida)

VAC
Volts AC

VADC
Attitude data control system motor drive voltage

VADCS
Attitude data control system motor drive voltage system

VADIS
Voice and Data Integrated System

VAJ
Feed forward term when firing axial thruster

VALV
Valve

VAN
Value Added Network

VAS
Value Added Service

VBD
Voice band data

VBTS
Beacon Tracking System motor drive voltage

VCC
Vehicle Command Count. Used with encryption

VCD
Valve Coil Driver

VCO
Voltage Controlled Oscillator

VCXO
Voltage Control Crystal Oscillator

VDA
Vapor Deposited Aluminum

VDDA
Variable Destination Demand Assignment

VDT
Visual display terminal

VDU
Video Display Unit

VELCOR
Velocity Correction

VF
Voice Frequency

VFO
Variable Frequency Oscillator

VFR
Visual Flight Rules (ICAO)

VFT
Voice Frequency Telegraph

VGA
Video Graphics Adapter

VHF
Very High Frequencies (Band 8)

VHRR
Very High Resolution Radiometer

VIAS
Voice Intelligibility Analysis Set

VID
Video

VIP
Versatile Information Processor

VIR
Vertical Interval Reference Signal

VIS
Video Short-term

VISSR
Visible and Infrared Spin Scan Radiometer

VITEAC
Video Transmission Engineering Advisory Committee (USA)

VITS
Verification International Test Signal

VLBI
Very Long Base Interferometer

VLF
Very Low Frequencies (Band 4)

VLR
Very Long Range

VLSI
Very Large Scale Integrations

VMOS
Vertical Metal-oxide Semiconductor

VN
Verification tests

Vne
Never exceed [a specific velocity]

VOC
Video Operations Center

VOD
Video on Demand

VODAS
Voice Operated Device Anti-Singing

VOGAD
Voice Operated Gain Adjusting Device

VOLNA
Mobile Satellite Network (Russian Federation)

VOM
Volt-ohm-milliammeter

VOR
VHF Omnidirectional Radio Range

VOW
Voice orderwire

VOX
Intersyllabic Voice Activated Carrier

VPD
Variable Power Divider

VPF
Vertical Processing Facility (KSC)

VPN
Virtual Private Network

VPS
Variable phase shifters

VRE
Voice Recognition Equipment

VRJ
Feed Forward term when firing radial thruster

VRMS
Volts RMS

VSAT
Very Small Aperture Terminal

VSB
Vertical Sideband

VSDM
Variable slope delta modulation (encoding technique)

VSG
Video Stripchart Generator

VSM
Vestigial Sideband Modulation

VSP
Virtual Switching Point

VSWR
Voltage Standing Wave Ratio

VT
Vertical Tabulation

VTF
Via Terrestrial Facilities

VTPR
Vertical Temperature Profile Radiometer

VTR
Video Tape Recording

VTVM
Vacuum Tube Voltmeter (syn.: Valve Voltmeter)

Vu OR VU
Volume Unit

VVC
Voltage-Variable

W or w
W Electrical energy

W/G
Waveguide

WAN
Wide Area Network

WARC
World Administrative Radio Conference

WATCHDOG
Timer for checking ACE operation

WATS
Wide area telephone service

WATSS
Wide Area Telephone Service System

WB
Wet Bulb

WBD
Wideband Data (Channel)

WBEAF
Wideband Earth Station Antenna Feed

WBFM
Wideband Frequency Modulation

WBPA
Wideband Power Amplifier

WBS
Work Breakdown Structure

WBSARC
World Broadcasting Satellite Administrative Radio Conference

WBTVR
Wideband Video Tape Recorder

WDC
World Data Center (Rockets and Satellites)

WEFAX
Weather Facsimile

WESTAR
Western Union Telegraph Communication Satellite (USA)

WF
Weighing Function

WG
Waveguide

WGN
White gaussian noise

Wh
Watthour

WHO
World Health Organization (UN)

WISI
World Index of Space Imagery

WMC
World Meteorological Center

WMO
World Meteorological Organization (UN)

WMS
World Magnetic Survey

WORM
Write-Once Read-Many (memory storage)

WP
Working Party (CCIR/CCITT)

wpm OR WPM
Words Per Minute

WRTC
Working Reference Telephone Circuit

Ws
Wattsecond

WSMC
Western Space and Missile Center

WTG
Weighing

WWVB
National Bureau of Standards Radio Station (Boulder, Colorado)

WWW
World Weather Watch

X
Combined Services (CCITT)

X-band
frequency spectrum in the 8/7 GHz range

X-POL OR X-Pol
Cross-polarized

X-Strp OR X-STRP
Cross-strap

XCE
Transponder Command Electronics

XDCR
Transducer

XIPS
Xenon Ion Propulsion Subsystem

Xmit
Transmit

XMTR
Transmitter

XPD
Cross-Polar Discrimination/Decoupling

XPDR
Transponder

XPI
Cross Polar Interference

XSE/XDE
Transponder Sequencer and Driver Electronics

XSSF
Scanner Synch Failure

XTAL
Crystal

XTE
Transponder Telemetry Electronics

Y
Admittance (phys.)

z or Z
z Figure of merit (elec. eng.)

Z-CAL
Zero Range Calibration

ZRT
Zero Range Transponder

ZT
Zone Time