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Glossary of Terms

0VR Zero Volt Return
2B+D Two Bearer Plus Data
2B1Q 2 Binary 1 Quaternary
2FSK Binary Frequency Shift Keying
3G 3rd Generation
4G 4th Generation
4WTO 4-Wire Transmission Only
A/D Analog-to-Digital converter
AAB Auto Answer Back
AAC Advanced Audio Coding
AACS Advanced Access Content System
AAL's ATM Adaption Layers
AAM Audio Adaptor Modules
AAR Automatic Alternative Route
ABI Application Binary Interface (Unix)
ABM Adaptive Bandwidth Management
ABR Available Bit Rate
AC Alternating Current
AC-3 Audio Codec 3
ACC Advanced Computer Communications
ACD Automatic Call Distribution
ACIA Asynchronous Communications Interface Adaptor
ACK Acknowledge ( char06 - 06H )
ACM Audio Compressor Module
ACO/LT Alarm Cut Off / Lamp Test
ACP Adjacent Channel Power
ACR Attenuation to Crosstalk Ratio
ACT Absolute Congestion Threshold
ADC Analogue to Digital Converter
ADCCMP Advanced data Communications Control Procedures (ANSI X3,66)
ADI Automatic or Alternate Digit Inversion
ADM Add/Drop Multiplex
ADP Automatic Data Processing
ADPCM Adaptive Differential Pulse Code Modulation
ADSI Analogue Display Services Interface
ADSL Asymmetric Digital Subscriber Line
ADX Automatic Data Exchange
AE Aerial
AES/EBU Audio Engineering Society/European Broadcasting Union
AF Audio Frequency
AFC Automatic Frequency Control
AFD Active Format Descriptor
AFT Automatic Fine Tuning
AGC Automatic Gain Control
AIN Advanced Intelligent Network
AIS Alarm Indication Signal
ALAPB Autosynchronous Link Access Protocol, Balanced
ALC Automatic Level Control
ALI Automatic Location Identification
ALN Adaptive Logic Network
ALSC Automatic Level and Slope Control
ALU Arithmetic and Logic Unit
AM Amplitude Modulation
AMI Alternate Mark Inversion
AML Amplitude Modulated Link
AMLCD Active Matrix LCD
AMPS American Mobile Phone System/Advanced Mobile Phone System
AMUSE Advanced Multimedia Services for Residential Users
AM-VSB Amplitude Modulation - Vestigial Sideband
ANGA Annual European trade show for Cable, Broadband and Satellite in Cologne Germany
ANI Automatic Number Identification
ANM Advanced Network Management
ANS Automatic Network Synchronization
ANS v2 Automatic Network Synchronization version 2
ANSI American National Standards Institute
ANSU American National Standards Unit
AOS Alternative Operator Services
APC Angular Physical Contact
APD Avalanche Photo Diode
API Application Programming Interface
APPN Advanced Peer to Peer Networking
APS Automatic Protection Switching
AQA Activity Qualified Access
ARCnet Advancd Resource Computer Network
ARM. Advanced Risc Machines
ARPA Advanced Research Projects Agency
ARQ Automatic Repeat Request
ARU Automatic Response Unit
ASC Abnormal Station Code; Automatic Slope Control
ASCII American Standard Code for Information Interchange
ASIC Application Specific Integrated Circuit
ASID Application Specific Integrated Device
ASK Amplitude Shift Keying
ASR Automatic Send Receive
ATDM Asynchronous Time Division Multiplex(er)
ATE Automated Test Equipment
ATIS Alliance for Telecommunications Industry Solutions
ATM Asynchronous Transfer Mode
ATS Abstract Test Suite
ATSC Advanced Television Systems Committee
ATV Advanced Television
AUI Attachment Unit Interface (Ethernet - 15 oin)
AV Audio-Video
AVC Advanced Video Coding
AVI Audio Video Interleave (Microsoft)
AVS Audio Video Standard
AWC Area Wide Center
AWG American Wire Gauge
AWGN Additive White Gausian Noise
B8ZS Binary 8-Zero Suppression
BAA British Astronomical Association
BABT British Approvals Board for Telecommunications
Balun BALanced to Unbalanced
BASIC Beginners All-purpose Symbolic Instruction Code
BAT Bouquet Association Table (multiplex) (part of SI)
BAW Bukk Acoustic Wave
BB Base Band
BBTH Broadband to The Home
Bc Excess Burst Size
BCC  Black Check Character
BCD Binary Coded Decimal
BCFS Bidirectional Coding Frame Structure
BCH Base-Chadhuri-Hocquenghem
BD Blu-ray Disc
BECN Backward Explicit Congestion Notification
BER Bit Error Ratio
BERT Bit Error Rate Tester
BETRS Basic Exchange Telecommunications Radio Service
B-FRAME Bidirectionally Predictive-coded (B) Pictures
BFSK Binary Frequency Shift Keying
BFT Binary File Transfer
BGA Bumped (Ball) Grid Array
BHCC Busy Hour Call Completion
BIL Basic impulse Insulation Level
BIP-8 Bit Interleaved Parity-8
BISDN Broadband Integrated Services Digital Network
B-ISDN Broadband Integrated Services Digital Network
BIST Built In Self Test
BISUP Broadband ISdn User Part
BIT. Built In Test
BITS Building Integrated Timing System
BML Business Management Layer
BNC Bayonet Neil-Councilman Connector
BNF Backus-Naur Form
BOP Bit Oriented Protocol
BPF Band Pass Filter
B-pictures Bidirectionally Predictive Pictures (motion compensation)
BPS b/s, Bits Per Second
BPSK Binary Phase Shift Keying
BRA Basic Rate Access
BRAN Broadband Radio Access Networks
BRI Basic Rate Interface
BRISC Bi-polar/BiCMOS reduced instruction set computer
BRR Bit-Reduction Rate
BSC Binary Synchronous Communications
BSF Band Stop Filter
BSI British Standards Institute
BSS Broadcast Satellite Service
BT British Telecom
BTAM Basic Telecommunications Access Method
BTSC Broadcast Television Systems Committee
BW Bandwidth
C Capacitance
C/N Carrier to Noise Ratio
CA Conditional Access; Commercial Announcement
CAC Carrier Access Code
CACS Conditional Access Control System
CAD Computer-Aided Design
CAE Computer-Aided Engineering
CAI Common Air Interface: Confederation of Aerial Industries
CAM Computer Aided Manufacturing
CAP Carrier-less Amplitude and Phase technology
CAPs Competitive Access Providers
CARS Community Antenna Relay Station
CAS Channel Associated Signaling
CAT Conditional Access Table (multiplex) (part of SI)
CATG Computer-Aided Test Generator
CATS Computer Aided Transmitter Simulation
CATV Cable (Community) Aerial Television System
CB Citizens Band
Cb, Cr Chrominance, equivalent to U,(-Y) and V, (R-Y)
CBDS Connectionless Broadband data Service
CBR Constant Bit Rate
CBTE Control Bus Telephony Extension
CBW Central Battery Working
CC Closed Caption
CCA Circuit Card Assembly
CCC Computer Control Center
CCD Charge Coupled Device
CCETT Center Common d'Etudes de Telediffusion et Telecommunications
CCF Custom Calling Features
CCFL Cold Cathode Fluorescent Lamp
CCIR-601 Comite Consultatif International des Radio Communications (France)
CCITT Comite Consultatif International de Telegraphique et Telephone
CCM Companding Conversion Module
CCN Configuration and Control Network
CCS Compression Control System, Computer Control System
CCSS Communications Channel Signalling System
CCTV Closed Circuit Television
CCU Camera Control Unit
CD Carrier Detect; Compact Disc
CDDI Copper Distributed Data Interface
CD-I Compact-Disc Interactive (Phillips)
CDM Code Division Multiplex
CDMA Code Division Multiple Access (Qualcomm)
CDPD Cellular Digital Packet Data
CDR Common Data Rate
CDV Cell Delay Variation
CEBus Consumer Electronics Bus
CEC Consumer Electronics Control
CEI Commission Electronique International
CELPC Code Excited Linear Predictive Coding
CEN Comite Europeen de Nornalisation
CENELEC Comite Europeen de Nornalisation Electrotechnique
CEPT Conference European des Administrations des Postes et Telecommunications
CER Cell Error Rate
CEV Controlled Environmental Vault
CFSK Coherent Frequency Shift Keying
CH Cable Headend
CHAP Challenge handshae Authentication Protocol
CHOTS Corporate Headquarters Office Technology System
CI Craft Interface, Control Information
CIC Carrier Identification Code; Cable In Conduit
CIDR Classless Inter-Domain Routing
CIE Commission International de L'Eclairage
CIF Common Intermediate Format: Common Image Format
CIN Computer Integrated Manufacturing
CIR Committed Information Rate
CIRC Cross-Interleaved Reed-solomon Code.
CISC Complex Instruction Set Computer
CISDR Common Image Structure Data Rate
CISPR Comite International des Perturbations Radiotechniques
CIU Customer Interface Unit
CK Category Key
CLASS Custom Local Area Signaling Services
CLI Cumulative Leakage Index
CLID Calling Line Identification
CLNP ConnectionLess Network Protocol
CLNS ConnectionLess Network Service
CLP Cell Loss Priority
CLR Cell Loss Ratio
CLUT Colour Look Up Table
CM Controller/Multiplexer; Cable Modem
CMI Control Module Idle
CMIP Common Management Information Protocol
CMRR Common-Mode Rejection Ratio
CMTS Cable Modem Termination System
CNET French National Center for Scientific Research
CNR C/N, Carrier to Noise Ratio
CO Central Office
COB Chip On Board
COBOL Common Business Oriented Language
CODEC Code/Decode
COFDM Coded Orthogonal Frequency Division Multiplexing
COMSAT Communications Satellite Corporation
COOLAN Central Office-based Local Area Network
CORBA Common Request Object Broker Architecture
COS Corporation for Open Systems
COSHH Control Of Substances hazardous to Health
COST Cooperation on Science and Technology
COT Customer Originated Trace
CPD Common path Distortion
CPE Customer Premise Equipment; Control Processing Equipment
CPFSK Continuous Phase Frequency Shift Keying
CPGA Ceramic Pin Grid Array
CPLD Complex Programmable Logic Device
CPM Continuous Phase Modulation
CPPM (CPRM) Content Protection for Recordable Media
CPS Characters Per Second
CPSS Control Packet Switching System
CPSS v2 Control Packet Switching System version 2
CPT Cable Pass Thro
CPU Central Processing Unit
CQFP Ceramic Quad Flatpack
CR Carriage Return ( char 13 - 0DH )
CRC Cyclic Redundancy Check
CRPE Center for Environmental Physics Research
CRT Cathode Ray Tube
CSA Canadian Standards Association
CSDN Circuit Switched Data Network
CSI Channel Status Information
CSMA Carrier Sense Multiple Access
CSMA/CA Carrier Sense Multiple Access/ Collision Avoidance
CSMA/CD Carrier Sense Multiple Access/ Collision Detection
CSO Composite Second Order
CSR Customer Service Representative
CSS Channel Synchronization Sequence; Content Scamble System
CSS (scrambling) Content Scramble System
CSSA Computing Services and Software Association 
CSSB/AM Companded Single Sideband/ Amplitude Modulation
CSU Channel Service Unit
CT Cordless Telephone
CTB Composite Triple Beat
CTD Cell Transfer Delay / Charge Transfer Device
CTS Cable Test System: Clear To Send
CVSD Continuously Variable Slope Delta-modulation
CVT Constant Voltage Transformer 
CW Carrier Wave; Continuous Wave; Control Word
CWS Can We Serve
D/A Data Acquisition
DAB Digital Audio Broadcasting
DAB+ Digital Audio Broadcasting plus (upgrade to the DAB standard using HE-AAC v2 audio coding)
DAC Digital to Analogue Convertor
DALS Dedicated Line Access
DAMA Demand Assigned Multiple Access
DAPSK Differential Amplitude Phase Shift Keying
DASS Digital Access Signalling Standard
DAT Digital Audio Tape
DATV Direct Antenna Television
DAVC Digital Audio Video Council
DAVIC Digital Audio Video Council
dB Decibel
dBc Decibel relative to Carrier
dBc/Hz Decibel relative to Carrier in one Hz bandwidth (Phase noise)
dBi Decibel relative to isotropic source
dBK Decibel relative to 1 deg K
dBm Decibel Milliwatt
dBm0 Decibel relative to 1mW at point of zero reference level
dBm0p as dBm0 but psophometrically weighted
dBm0ps as dBm0p but weighted for audio transmission
dBmV decibels relative to 1mV
DBPSK Differential Binary Phase-Shift Keying
DBPT Deutsche Bundespost Telecom
DBS Direct Broadcast Satellite
dBuV decibels relative to 1uV
dBV decibels relative to 1V
dBW Decibel Watt
DC Direct Current; Direct Coupler
DCC Direct Card Connect, Digital Compact Cassettes; Data Communications Channel
DCD Data Carrier Detect; Duty Cycle Distortion
DCE Data Communications Equipment: Data Circuit terminating Equipment
DCM Direct Connect Module
DCN Data Communications Network
DCP Data Communications Processor
DCS Diagnostic and Control System, Digital Cross-connect System
DCT Discrete Cosine Transform
DD Dolby Digital
DDC Digital Down Converter
DDCMP Digital Data Communications Message Protocol
DDD Direct long- Distance Dialling
DDJ Data Dependent Jitter
DDS Direct Digital Synthesis, Dataphone Digital Service: Digital Data Service
DE Discard Eligible
DEA Digital Encryption Algorithm
DECT Digital Enhanced Cordless Telecommunications
DES Data Encryption Standard
DFB Distributed Feedback
DFM Design For Manufactureability
DFR Digital Fault Recorder
DFSK Differential Phase Shift Keying
DFT Design For Test: Discrete Fourier Transform
DHCP Dynamic Host Configuration Protocol
DIA Data Interface Adapter
DID Direct Inward Dialing
DIN Deutsche Industrie Normen
DisEqC Digital Satellite Equipment Control
DIU  Data Interface Unit
DLC Digital Loop Carrier:  Data Link Control
DLIC Data Link Connection Identifier
DLSw Data Link Switching
DM Delta Modulation
DMA Direct Memory Access
DMB Digital Multimedia Broadcasting
DMM Digital MultiMeter
DMS Digital Multiplex Systems
DMT Design Maturity Testing; Discrete Multitone
DNIC Digital Network Interface Circuit
DNS Domain Name System ( Internet )
DOC Department of Communications
DOCSIS Data Over Cable Service Interface Specification
DOPSK Differential Offset Phase Shift Keying
DOS Disc Operating System
DP Dial Pulsing
DPAK Power Transistor Surface Mount Package
DPCM Differential Pulse Code Modulation
DPDT Double-Pole, Double-Throw ( switch )
DPM Digital Processor Module
DPM2 Digital Processor Module 2
DPN Data Packet Network
DPO Dial Pulse Originate
DPSK Differential Phase Shift Keying
DPT Dial Pulse Terminate
DQPSK Differential Quadrature Phase Shift Keying
DR. Dynamic Range
DRAGA Dual Rate Adaption Gate Array
DRAM Dynamic Random Access Memory
DRC Dynamic Range Control
DRM Digital Radio Mondiale
DS Digital Signal
DS/CDMA Direct Sequence CDMA
DS/PPM Direct Sequence Pulse Position Modulation
DS0 Digital Service level 0
DS-0 Digital Signal Level 0 (64Kbps), Usually single voice channel
DS-1 Digital Signal Level 1 (1.554 Mbps) 24 voice or other data services
DS-3 Digital Signal Level 3 (45 Mbps) 28 DS-1 circuits
DSB Double Sideband Modulation
DSBSC Double Sideband Suppressed Carrier
DSD Direct Stream Digital
DSI Digital Speech Interpolation
DSL Digital Subscriber Line
DSM Digital Storage Medium
DSNG Digital Satellite News Gathering
DSP Digital Signal Processing
DSR Digital Storage and Retrieval: Data Set Ready
DSS Digital Satellite Service or Digital Satellite System
DSSS Direct Sequence Spread Spectrum
DS-SSMA Direct Sequence-Spread Spectrum Multiple Access
DSU Digital Switch Unit, Data Service Unit
DSX-1 Digital Signal Cross-Connect Level 1
DTC Department of Trade Controls; Decoder Time Clock
DTE Data Termination Equipment
DTH Direct To Home
DTI Department of Trade and Industry
DTM Digital TransModulation
DTMF Dual Tone Multiple Frequency
DTR Data Terminal Ready
DTS Digital Time Stamp
DTS (sound system) Digital Theater Systems
DTT Digital Terrestrial Television
dTTb Digital Terrestrial Television Broadcasting
DTU Data Termination Unit
DTVC Digital Television by Cable
DUT Device Under Test
DV Digital Video
DVB Digital Video Broadcasting
DVB-C Digital Video Broadcasting - Cable
DVB-C2 Digital Video Broadcasting - Cable - Second Generation
DVB-H Digital Video Broadcasting - Handheld
DVB-NGH Digital Video Broadcasting - Next Generation Handheld
DVB-S Digital Video Broadcasting - Satellite
DVB-S2 Digital Video Broadcasting - Satellite - Second Generation
DVB-SH Digital Video Broadcasting - Satellite Handheld
DVB-T Digital Video Broadcasting - Terrestrial
DVB-T2 Digital Video Broadcasting - Terrestrial - Second Generation
DVC Digital Video Compression
DVD Digital Video Disc
DVI Digital Visual Interface
DVMD Digital Video Measurement Decoder
DVQ Digital Video Quality
DVRM Digital Video Realtime Monitor
DVT Design Verification Test
DWDM Dense Wavelength Division Multiplexing
DWMT Discrete Wavelet Multitone
DWS Dialable Wideband Service
DX Digital Cross-connect
E1 European Signal Level 1 (Line Rate: 2.048 Mbps)
E2 European Signal Level 2 (Line Rate: 8.448 Mbps)
E3 European Signal Level 3 (Line Rate: 34.368 Mbps)
EAEO Equal Access End Office
EAS Emergency Alert System
EAX Electronic Automatic Exchange; Extended Area Service
EBCDC Extended Binary Coded Decimal Code
EBCDIC Extended Binary Coded Decimal Interchange Code
EBU European Broadcasting Union
EC European Community, Earth Calling
ECL Emitter Coupled Logic
ECM Entitlement Control Messages / Electronic Counter-Measures
ECS European Communications Satellite
ECSA Exchange carrier Standards Association
EDC Error Detection and Correction
EDFA Erbium-Doped Fibre Amplifier (1550nm)
EDGE Enhanced Data Rates for Global Evolution
EDI Electronic Data Exchange, Electronic Document Interchange
EDS Electronic Data Service
EDTV Extended Definition Television
EEPROM Electrically Erasable Programmable Read-only Memory
EFP Electronic Film Production
EGP Exterior Gateway Protocol
EIA Electronic Industries Association
EIAJ Electronic Industry Association Japan
EIRP Effective Isotropic Radiated Power; Equivalent Isotropic Radiated Power
EISA Enhanced Industry Standard Architecture
EIT Event Information Table (multiplex) (part of SI)
ELF Extremely Low Frequency
ELGDVB European Launch Group for Digital Video Broadcasting
EM ElectroMagnetic
EMC Electromagnetic Capability
EMF Electromagnetic Flux
EMI Electromagnetic Interference
EML Element Management Area
EMM Entitlement Management Messages
EMP Electromagnetic Pulse
EMR European Metal Recycling
ENF Equivalent Noise Floor
ENG Electronic News Gathering
ENQ Enquiry
EO&C Expert Observation & Commentary
EOF End Of File / End Of Frame
EOP End Of Packet
EOT End Of Transmission
EPAC Electricaly Programmable Analogue Circuit
EPG Electronic Program Guide
EPLD Erasable Programmable Device
EPROM Erasable Programmable Read-only Memory
EQ Equipment Qualification
ERA Electrically Reconfigurable Array
ERL Echo Return Loss
ERM Electromagnetic compatibility and Radio spectrum Matters
ERP Effective Radiated Power
ESA Emergency Stand Alone
ESCR Elementary Stream Clock Reference
ESD Electrostatic Discharge
ESDi Enhanced Small Device Interface
ESF Extended Super Frame
ESP Enhanced Service Provider
ESS Electronic Switching System
ET Emerging Technologies
ETB End of Text Block
ETDMA Enhanced Time Division Multiple Access
ETS European Technical Standard
ETSI European Telecommunication Standard Institute
EVC Enhanced Video Connector ( VESA )
EVM Error Vector Magnitude
EWP Electronic White Pages
FAD Frame Relay Assembler / Disassembler
FAP Flexible Access Protocol
FAS Frame Alignment Signal
FAT Factory Acceptance Test / File Allocation Table
FAX Facsimile
FC Fibre Channel
FCC Federal Communications Commission
FCP Fault Condition Propagation
FCS Frame Check Sequence
FDDI Fibre Distributed Data Interface
FDL Facility Data Link
FDM Frequency Division Multiplexing
FDMA Frequency Division Multiple Access
FDX Full DupleX
FEC Forward Error Correction
FECN Forward Explicit Congestion Notification
FED Field Emission Display
FEI Federation of  the Electronics Industry
FERF Far End Receive Failure
FFT Fast Fourier Transformation
FHT Fast Hartley Transform
FIC Fast Information Channel
FIFO First In First Out
FIP FASTbus Interconnect Panel
FIR Finite Impulse Response (Digital Filtering Technique)
FIT Failures in 1 Billion Hours
FITL Fibre In The Loop
FLAG Fibre Link Around the Globe.
FLIR Forward Looking Infra-Red
FLP Fluorescent Panel
FM Frequency Modulation
FML Frequency Modulation Link
FMO Frequency Modulation Oscillator
FO Fibre Optic
FOSE Fibre Optic Splice Enclosure
FOT Fibre Optic Transceiver
FOTS Fibre Optic Transmission Systems
F-P Fabry-Perot
FPD Flat Panel Display
FPGA Field Programmable Gate Arrays
FPLD Field Programmable Logic Device
fps frames per second
FR Frame Relay
FRAD Frame Relay Assembly/ Disassembler
FRE Frame Relay Engine
FRS Frame Relay Switch
FSIC Function Specific Integrated Circuit
FSK Frequency Shift Keying
FSM Field Strength Meter
FSN Full Service Network
FSS Fixed Satellite Services
FT1 Fractional T1
FTAM File Transfer and Access Management
FTP File Transfer Protocol
FTTC Fibre To The Curb
FTTF Fibre To The Feeder
FTTH Fibre To The Home
FttX Fibre to the Whatever.
FWHM Full Width Half Maxima
FX Foreign Exchange Service - Office
FXO Foreign Exchange
FXS Foreign Exchange Service - Subscriber



Gain-to-Noise Temperature Ratio
G3 Gadolinium Gallium Garnet
G703 34.4 Mb/s
G709 155.2 Mb/s
G751 139.264 Mb/s
Ga As P Gallium Arsenide Phosphide
Ga N Gallium Nitride
GaAsFET Gallium Arsenide Field Effect Transistor
GARP Global Atmospheric Research Program
GDI Generic Data Interface
GENEVA GenRad Extended VXIbus Archtecture
GEO Geosynchronous Earth Orbit
GFC General Facilities Card
GFMSK Gausian Filtering Minimum Shift Keying
GFSK Gausian filtered Frequency Shift Keying
GHz Gigahertz
GI Graded Index
GIS Geographical Information System
GLONASS GLObal NAvigation Satellite System
GMS Geostationary Meteorological Satellite
GMSK Gausian Minimum Shift Keying
GND Ground
GOES Geostationary Operational Environmental Satellite
GOMS Geostationary Operational Meteorological Satellite
GOP Group Of Pictures (motion compensation)
GPIB General Purpose Interface Bus (IEEE-488,HP-1B; Transfer rate <1 Mbps)
GPRS General Packet Radio Service
GPS Global Positioning System
GS Ground Start
GSM Global Standard for Mobile communication
GUI Graphical User Interface
H.261 ITU-T video coding standard primarily for ISDN
H.264 Coding standard for video compression
H.264/MPEG-4 AVC Coding standard for video compression developed by ITU-T
HA Home Access
HAD. Hole Accumulation Diode
HAN Home Area Network
HB Home Bridge
HBI Horizontal Blanking Interval
HC Home Client
HCI Host Controller Interface
HCM High Capacity Multiplexing
HCT Home Communication Terminal
HCV High Capacity Voice
HD High Definition
HDB High Density Bi-polar
HDCP High-bandwidth Digital Content Protection
HDD Hard Disk Drive
HDLC High Level Data Link Controller
HDMI High-Definition Multimedia Interface
HDSL High bit rate Digital Subscriber Line
HDT Host Digital Terminal; Headend Digital Terminal
HDTV High Definition Television
HDX Half Duplex Transmission
HE-AAC High Efficiency Advanced Audio Coding standardised in ISO/IEC 14496-3
HEMT High Electron Mobility Transistor
HEX Hexadecimal Notation
HF Hih Frequency
HFC Hybrid Fibre-Coax
HFW Hybrid Fibre Wireless
HID Human Interface Device
Hiperlan High Performance Radio LAN
HITS Headend In The Sky
HLD High Level Design
HLDD High Level Design Document
HLR Home Location Register
HMU Home Monitoring Unit
HPB Half-Power Bandwidth
HPF High Pass Filter
HRC Harmonically Related Carriers
HSCD High Speed Data Cable
HSCSD High Speed Circuit Switching Data
HSSI High Speed Serial Interface
HTML HyperText Markup Language
HTTP HyperText Transfer Protocol
HUD Head-Up Display
Hz Hertz ( = Cycles per Second )
I In-Phase
I, Q In Phase, Quadrature phase components of the modulated signal.
I/O Input Output
IBC International Broadcasting Conference)
IBOC In Band On Channel
IBPSK Independent Binary Phase Shift Keying
IBR Intermediate Bit Rate
IC Integrated Circuit
ICC Incremental Coherent Carriers
ICI Inter-carrier Interface
ICN Integrated Community Network
ICS Integrated Communication System
ICW Interrupted Continuous Wave
IDCT Inverse Discrete Cosine Transform
IDD International Direct Dialling
IDF Intermediate Distribution Frame
IDLC Integrated Digital Loop Carrier
IDN Integrated Digital Network
IDP Internet data Packet
IEC International Electrotechnical Commission
IEEE Institute of Electrical and Electronic Engineers
IF Intermediate Frequency
IFFT Inverse Fast Fourier Transformation
I-FRAME Intra Picture Frame Structure
IFRB International Frequency Registration Board
IGP Interior Gateway Protocol
IHC In Home Cabling
IIR Infinite Impulse Response. (Digital Filtering Technique)
IM Inter-Modulation
IMAP Internet Message Access Protocol
IMD Inter-Modulation Distortion
IMUX Input Multiplexer
INMS Integrated Network Management System
IOR Index Of Refraction
IP Internet Protocol; Intelligent Peripherals; Information Provider; Interlectual Property
I-pictures Intra-pictures (motion compensated)
IPPV Impulse Pay Per View
IPR Intellectual Property Rights
Ipv4 Internet Protocol version 4
Ipv6 Internet Protocol version 6
IRB Input Redundancy Bus
IRC Incrementally Related Carriers
IRD Integrated Receiver Decoder
IRED Infra Red Emitting Diode
IRIG-B Intermediate Range Instrumentation Group (Time Code Format)
IRL Inter-Repeater Link
IRP Integrated Receiver Processor
IRQ Interrupt Request
IRT Integrated Receiver Transcoder
IS2DN Integrated Special Services Digital Network
ISA Industry Standard Architecture
ISB Independent Side Band
ISD International Subscriber Dialling
ISDN Integrated Services Digital Network; Integrated Switched Digital Network
ISI International Symbol Interface; InterSymbol Interference
ISO International Standards Organization
ISP In System Programmability /Internet Service Providere
ISSU Intelligent System Synchronization Unit
ISU Integrated Services Unit
ITA Interface Test Adapter
ITB Integral Token Ring Bridge
ITFS Instructional Television Fixed Service
ITU International Telecommunications Union
ITV Interactive Television
IVR Interactive Voice Response
IWU Interworking Unit
JB7 Jam Bit 7
JEDEC Joint Electronic Devices Engineering Council
JESSI Joint European Sub-micron Silicon Initiative
JISC Japanese Industrial Standards Committee
JIT Just In Time
JND Just Noticeable Difference
JPEG Joint Photographic Experts Group
JTAG Joint Test Action Group (IEE 1149.1 Serial bus standard)
KB KiloBytes
kbps Kilo Bits Per Second
KHz Kilohertz
Ksps Kilosymbols Per Second
KSU Key Service Unit
LAN Local Area Network
LAPB Link Access Protocol - Balanced
LAP-M Link Access Protocol - Modem
LASER Light Amplification by Stimulated Emission of Radiation
LAT Local Aea Transport  ( DEC, Ethernet )
LBO Line Build Out
LCD Liquid Crystal Display
LCDC Loop Calling Disconnect Clear
LCS Leased Circuit Service
LDF Low Density Foam ( cables )
LDS Local Distribution Service
LEC Local Exchange Carriers
LED Light Emitting Diode
LEO Low Earth Orbit
LF Low Frequency
LGE Loop start Ground start - Exchange
LGS Loop start Ground start - Subscriber
LHCP Left Hand Circular polarisation
LIDAR Lightning Detection and Ranging.
LIFO Last In First Out
LIM Line Interface Module
LLD Low Level Design
LLDD Low Level Design Document
LMDS Local Multipoint Distribution Service
LMI Local Management Interface
LNA Low Noise Amplifier
LNB Low Noise Block converter
LNC Low Noise Converter
LO Local Oscillator
LON Local Operating Network
LOP Local Origination Programming
LOS Line Of Sight: Loss Of Signal
LPC Linear Predictive Coding
LPCM Linear Pulse Code Modulation
LPF Lowpass Filter
LPM Lines Per Minute
LPRA Low Power Radio Authority
LPS Lightning Protection System
LPTV Low Power Television
LR Line Reversal
LRB Loop Reverse Battery
LRC Longitudinal Redundancy Check
LS Loop Start
LSB Least Significant Bit
LSI Large Scale Integration
LSOH Low Smoke Zero Halogen
LTE Long Term Evolution - pre-4G standardby the 3rd Generation Partnership Project (3GPP) for increase of data capacity and speed of mobile (broadband) networks
LTE Advanced Long Term Evolution Advanced - Preliminary mobile communication standard, and candidate 4G system by the 3rd Generation Partnership Project (3GPP) as a major enhancement of the LTE standard.
LUF Lowest Usable Frequency
Luma Luminance (Y)
LUT Look Up Table
LVA Long Vertical Aperture
LVD Low Voltage Directive
M3VDS Millimeter-wave Multi-channel Multipoint Video Distribution System
MAC Multiple Analog Component format: Multiplying Accumulator
MAM Modulator Adaptor Module
MAN Metropolitan Area Network
MAP Manufacturing Automation Protocol / Multiple Access Protocols
MARECS MARitime European Communications Satellite
MASCAM Mask-pattern Adaptive Sub-band coding and Multiplexing
MATV Master Antenna Television
max Maximum
MBG Multilocation Business Group
Mbone Multicast backBone ( Internet )
Mbps Megabits Per Second
MCM Multi Chip Module
MCPC Multiple Channels Per Carrier
MCR Master Control Room
MCT Mild Congestion Threshold
MCTDMA Multiple Carrier Time Division Multiple Access
MCW Modulated Continuous Wave
MDDB Multidrop Data Bridge
MDF Main Distribution Frame
MDS Multipoint Distribution Service: Microwave Distribution System
MDU Multiple Dwelling Unit
MEC Multiplexer Encryptor Encoder
MELF Metal Electrode Face Bonded
MEMS Micro-ElectroMechanical Systems
MER Modulation Error Ratio
MF Medium Frequency; Multi Frequency
MFLOPS Million Floating-Point Operations Per Second
MFN Multi Frequency Network / Modified Frequency Modulation
MFSK Multiple/ Minimum Frequency Shift Keying
MGC Manual Gain Control
MHEG-5 Multimedia & Hypermedia Information Coding Expert Group
MHS Message Handling System/ Service
MHz Megahertz
MIBS Management Information Bases
MIC Microwave Integrated Circuit
MID Mobile Information Device
MIER Modulation Error Ratio
MIME Multipurpose Internet Mail Extensions
MIMO Multiple-Input and Multiple-Output
MIP Megaframe Initialization Packet
MIPS Million Instructions Per Second
MISO Multiple-Input and Single-Output
MJU Multijunction Unit
MLP Meridian Lossless Compression ;Micro Lead Package
MM Multimode
MMDS Multichannel Multipoint Distribution Service (Microwave)
MMIC Monolithic Microwave Integrated Circuit
MMU Memory Management Unit
MNP Microcom Networking Protocol
MOAM Modulator Output Adaptor Module
Mod Modulator
MODEM Modulator/ Demodulator
MOS Metal-Oxide Semiconductor; Mean Opinion Score
MOVPE Metallic Organic Vapor Phase Epitaxy
MP3 MPEG-1 or MPEG-2 Audio Layer 3 (or III) - lossy compression algorithm for audio
MP4 MPEG-4 Part 14 - ISO/IEC 14496-14:2003, multimedia container format standard
MPAC Mask Programmable Analogue Circuit
MPEG-1 Motion Picture Experts Group (Digital Compression Standard ISO 11172)
MPEG-1 Audio Layer 3 Extension to the MPEG-1 standard for audio (ISO/IEC 11172-3, MPEG-1 Part 3)
MPEG-2 Motion Picture Experts Group (Digital Compression Standard ISO 13818)
MPEG-4 Motion Picture Experts Group (Digital Compression Standard ISO/IEC 14496 - Coding of audio-visual objects)
MPLS Multiprotocol Label Switching
MQFP Metric Quad Flat Pack
MQORC Modified Quadrature Overlapped Raised Cosine'
MRD Manual Ring Down
MSA Metropolitan Service Area
MSB Most Significant Bit
MSC Main Service Channel
MSK Minimum Shift Keying
MSO Multiple System Operator
Msps Megasymbols Per Second
MSRN Multiple Station Roaming Number
MSS Mobile Satellite Services
MTBF Mean Time Between Failure
MTF Modulation Transfer Function
MTS Modem Termination System; Multichannel Television Sound
MTSO Mobile Telephone Switching Office
MTTR Mean Time To Repairs
MUF Maximum Usable Frequency
MULDEX Multiplexer/ Demultiplexer
MUSA Multiple Unit Steerable Array
MUSE Multiple Sub-Nyquist Encoding
MUSHRA MUltiple Stimuli with Hidden Reference and Anchor
MUSICAM Masking Pattern Universal Sub-band Integrated Coding and Multiplexing
MUX Multiplexer
MVIP Multi Vendor Integration Protocol
MXIbus Multisystem Extension Interface Bus  (Transfer Rate <20 Mbytes per second)
NA Numerical Aperture
NAB National Association of Broadcasters
NADG North American Digital Group
NAK Negative Acknowledgement
NAMAS NAtional Measurement Accreditation Service
NAP Network Access Points
NAT4882 Industries First IEEE-488.2 Controller Chip
NAU Network Addressable Unit
NBFM Narrow Band Frequency Modulation
NBS National Bureau of Standards
NC Network Congestion / No Connection
NCC National Control Centers Telecommunication System
NCI Network Control Interface
NCP Network Control Program
NCTA North American Cable Television Association
ND:YAG Neodymium Yttrium Aluminum Garnet
NE Network Element
NEC Network Electrical Code
NEMA National Electrical Manufactures Association
NEP Noise Equivalent Power
NEXT Near-End Crosstalk
NF Noise Figure
NFAS Non-Frame Alignment Signal
NFS Network Filing System
NIC Network Information Carrier
NICAM Near Instantaneous Companded Audio Multiplex
NICQA National Inspection Council Quality Assurance
NID Network Interface Device
NII National Information Infrastructure
NIIR Russian Scientific Research Institute of Radio Communications
NIT Network Information Table (multiplex) (part of SI)
NIU Network Interface Unit
nm nanometres
NML Network Management Layer
NMS Network Management System
NMTI Node Management Terminal Interface
NNI Network-Network Interface; Network-Node Interface
NOAA National Oceanographic and Atmospheric Administration
NOC Network Operations Center
NRE Non-Recurring Engineering
NRZ Non Return to Zero
NRZI Non Return to Zero Inverted
NSF Non-Standard Facilities
NT Network Termination
NTSC National Television Standards Committee
NTU Network Termination Unit
NUI Network User Identification
NVM Non-Volatile Memory
NVOD Near Video On Demand
NVP Nominal Velocity of Propagation.
OA Office Automation
OAA Over Air Addressing
OC Optical Carrier
OC-12 655 Mb/s
OC-3 150 Mb/s
OC-48 2.4 Gb/s
OCC Other Common Carrier
OC-N Optical Carrier - N
OCU Office Channel Unit
OCU-DP Office Channel Unit - Data Port
ODI Open Data-link Interface
OEM Original Equipment Manufacture
OFDM Orthogonal Frequency Division Multiplexing
OFDMA Orthogonal Frequency Division Multiple Access
OFS Operational Fixed Station
OIRT Organisation International de Radiodiffusion et Television
OMT Orthognal Mode Transducer
OMUX Output Multiplexer
ONA Open Network Architecture
ONU Optical Network Units
OOF Out Of Frame
OOK On Off Keying
OOP Object Oriented Programming
OOS Out Of Service
OPGW overhead Optical Ground Wave
OPX Off Premises Extension
OQPSK Offset Quadrature Phase Shift Keying
ORL Optical Return Loss
OSC Oscillator
OSD On Screen Display
OSI Open Systems Interconnect
OSPF Open Shortest Path First
OSS Operations Support System
OTDR Optical Time Domain Reflectometer
OTG On Time Guarantee
OTN Optical Transmission Nodes
OTP One Time Programmable
OTS Orbital Test Satellite
OWF Optimum Working Frequency
P French term for SCART (connector)
P Puncturing
PABX Private Automatic Branch Exchange
PAD Packet Assembler/Disassembler, Program Associated Data
PAL Phase Alternating Line; Programmable Array Logic
PALC Plasma Addressed LCD
PALE Programmable Atomic Logic Elements
PAM Pulse-Amplitude Modulation
PARS Private Advanced Radio Service
PAT Program Association Table, (multiplex)(part of SI); Power Alignment Technology
PAX Private Automatic Exchange
PBGA Plastic Ball Grid Array
PBX Private Branch Exchange
PC Personal Computer; Printed Circuit
PCB Printed Circuit Board
PCC Programmer Control Center
PCI Peripheral Component Interconnect
PCM Pulse Code Modulation
PCMCIA Personal Computer Memory Card International Association
PCN Personal Communications Network
PCR Programmable Clock Reference
PCS Program Control System; Personal Communication Services
PCSN Private Circuit Switching Network
PDF Pulse Density Function; Portable Document Format
PDFA Praesodymium-Doped Fibre Amplifiers (1310nm)
PDH Plesiosyncronous Digital Heirarchy
PDM Phase Division Multiplex ;Passive Display Model: Pulse Duration Modulation
PDMI Portable Digital Media Interface
PDN Public Data Network; Primary Directory Number
PECL Pseudo ___________
PEL Picture Element
PES Packetized Elementary Stream, Personal Earth Station
PFD Power Flux Density
PFM Pulse Frequency Modulation
P-Frame Predictive-coded (P) Pictures Frame Structure
PGA Pin Grid Array
PID Program Identification, Packet Identifier
PIN Personal Identification Number
PIO Programmable Input Output
PIV Peak Inverse
PIXEL Peak Inverse Voltage
PK Program Key
PKI0 Public Key Infrastructure
PLA Programmable Logic Array
PLAR Private Line Automatic Ring down
PLC Programmable Logic Controller
PLCC Plastic Leaded Chip Carrier
PLD Programmable Logic Device
PLL Phase Locked Loop
PLMN Public Land Mobile Network
PLR Private Link Repeater
PLUGE Picture Line Up Generator Equipment
PM Phase Modulation, Poly-phase Matched
PMR Private Mobile Radio
PMT Program Map Table (multiplex) (part of SI)
PN Pseudo-random Number
PNNI Private Network to Network Interface
POCSAG Post Office Code Standardisation Advisory Group
POF Plastic Optical Fibre
PON Passive Optical Network
POP Proof Of Performance / Point of Presence
POS Programmable Option Select
POTS Plain Old Telephone Service
P-pictures Predictive pictures
PPM Pulse Position Modulation
PPP Point - to - Point Protocol
PPV Pay Per View
PQFP Plastic Quad Flatpack
PRA Primary Rate Access ( 2Mb/s - ISDN )
PRBS Pseudo Random Binary Sequence; Pseudo Random Bit Sequence
PRF Pulse Repetition Frequency
PRI Primary Rate Interface
PROM Programmable Read Only Memory
PSD Power Spectral Density; Programmable System Device
PSDN Packet Switched Data Network
PSI Program Specific Information (part of SI)
PSK Phase Shift Keying
PSS Packet Switched System/ Service
PSTN Public Switched Telephone Network
PSTS Profile Specific Test Specification
PSU Power Supply Unit
PT Packet Terminal
PTL PASS Transistor Logic
PTM Pulse Time Modulation
PTS Presentation Time Stamp
PTT Postal, Telephone and Telegraph
PTX Packet Transfer Exchange
PVC Permanent Virtual Connection
PVR Personal Video Recorder
PWA Printed Wiring Assembly
PWB Printed Wiring Board
PWM Pulse-Width Modulation
PWR Power
Q Quadrature
Q&R Quality and Reliability
QA Quality Assurance: Assessment
QAM Quadrature Amplitude Modulation
QASK Quadrature Amplitude Shift Keying
QCIF Quarter Common Intermediate/ Image Format
QDPSK Quadrature Differential Phase Shift Keying
QDU Quantisation Distortion Units
QEF Quasi Error Free (BER <10-11) (SNR 24.5dB FOR 64QAM)
QFP Quad Flat Package
QFSK Quadrature Frequency Shift Keying
QIRP QAM Integrated Receiver Processor
QORS Quadrature Offset Raised Cosine
QOS Quality Of Service
QOSRC Quadrature Overlapped Squared Raised Cosine
QPR Quadrature Partial Response
QPRS Quadrature Partial Response Signaling
QPSE Queued Packet Synchronous Exchange
QPSK Quadrature Phase Shift Keying, Quaternary Phase Shift Keying
QSOP Quater Small Outline Package
QWIP Quantum Well Infrared Photo Detector
R Randomised Sequence
R&D Research and Development
R2D R2 Digital Signaling
RAD Remote Antenna Device
RADAR Radio Detection And Ranging
RAE Royal Academy of Engineering
RAID Redundant Array of Inexpensive Discs
RAM Random Access Memory
RAPID Reserved Alternate Path with Immediate Diversion
RBER Residual Bit Error Rate
RBS Robbed Bit Signaling, Reserved Battery Signaling
RCC Radio Common Carrier
RCI Relay Control Interface
RDT Remote Digital Terminal
RE. Remote Extension
REM EXT Remote Extension
REN Ringer Equivalence Number
RF Radio Frequency
RFI Radio Frequency Interference
RFID Radio Frequency Identification
RHCP Right Hand Circular Polarisation
RIN Relative Noise Intensity
RIP Routing Information Protocol
RISC Reduced Instruction Set Computer
RL Return Loss
RLC Run Length Coding
RLR Return Loss Ratio
RM Rack Mount
RMS Root Mean Square
RMSD Root Mean Square Deviation
RMU Rack Mounting Unit
ROM Read Only Memory
RPC Remote Procedure Call
RR Ring Return
RS Reed Solomon
RSA Rural Service Area
RSL Received Signal Level
RST Running Status Table (multiplex)
RTC Real Time Clock
RTOS Real Time Operating System
RTS Request To Send
RTT Round Trip Time
RTV Real-Time Video
RU Rack Unit (1.75'high X 19' wide)
RX Receiver
RXD Received Data
S/I Signal to Interference
S/N Signal to Noise Ratio
S/PDIF Sony/Philips Digital Interconnect Format
SA Spatial Activity
SACD Super Audio Compact Disc
SAM Super-rate Adapter Module
SAP Second Audio Program / Service Access Point
SAR Segmentation And Reassembly
SAW Surface Acoustic Wave Filter
SB Signal Battery
SBCA Satellite Broadcasting and Communications Association
SBS Satellite Business Systems
SCAI Switch to Computer Applications Interface
SCART Syndicat des Constructeurs d'Appareils Radior
SCC System Control Computer
SCC3 System Control Card 3
SCD Specification Control Document, Single Channel Decoder
S-CDMA Synchronous Code Division Multiplex Access
SCE Service Creation Environment
SC-FDMA Single Carrier Frequency Division Multiple Access
SCI Scalable Coherent Interface
SCM Single Carrier Modulation
SCN Serial Control Network
SCO Synchronous Connection Oriented
SCP Service Control Point
SCPC Single Channel Per Carrier
SCR System Clock Reference / Silicon Controlled Rectifier
SCSI Small Computer System Interface
SCT Single Carrier Transcoder, Severe Congestion Threshold
SCTE Society of Cable Telecommunication Engineers
SDA Synchronous Data Adapter
SDB Serial Distribution Bus
SDDS Sony Dynamic Digital Sound
SDH Synchronous Digital Hierarchy
SDI Synchronous Data Interface
SDLC Synchronous Data Link Control
SDP Synchronous Data Processor
SDR Satellite Digital Radio
SDS 56 Switched Data Services (56kbps)
SDSL Single-line Digital Subscriber Line
SDT Service Description Table (multiplex) (part of SI)
SDU Service Data Unit
SDV Switched Digital Video
SECAM Sequential Colour with Memory
SF Superframe Format
SFN Signal Frequency Network
SFTP Shielded Foil Twisted Pair
SGDF Super-Group Distribution Frame
SHDL Symmetrical High Speed Digital Subscriber Line
SHL Studio to Headend Link
SHN Self Healing Network
SI System Information; Service Information; Step Index
SIMD Single Instruction Multiple Data
SIMO Single Input - Multiple Output
SIR Sustained Information Rate
SISO Single Input - Single Output
SLC Subscriber Line Carrier
SLIC Subscriber Line Interface Circuit
SLIP Serial Line Internet Protocol
SLM Signal Level Meter
SLS Single Line Service
SM Single Mode
SMATV Satellite Master Antenna Television System
SMD Surface Mount Device
SMDR Station Message Detail Recording
SMDS Switched Multimegabit Data Service
SMF Single Mode Fibre
SML Service Management Layer
SMPS Switching Mode Power Supply
SMPTE Society of Motion Picture and Television Engineers
SMR Signal to Mask Ratio; Specialized Mobile Radio
SMS Subscriber Management System
SMSR Side Mode Suppression Ratio
SMT Surface Mount Technology
SMTP Simple Mail Transfer Protocol
SNA Systems Network Architecture
SNAIP Simple Network Management Protocol
SNG Satellite News Gathering
SNMP Simple Network Management Protocol
SNOC Satellite Network Operations Center
SNR Signal to Noise Ratio
SO Small Outline (IC Package)
SOJ Small Outline (J-lead)
SONET Synchronous Optical Network
SOP Small Outline Package; Standard Operating Procedure
SOT Small Outline Transistor
SPAN Service and Protocols for Advanced Network
SPB Serial Packet Bus
SPC Statistical Process Control, Super Physical Contact; Stored Program Control
SPE Synchronous Payload Envelope
SPECTRE Special Purpose Extra Resolution for Terrestrial Enhancements
SPM Self-Phase Modulation
sps symbols per second
SPST Single Pole - Single Throw (switch )
SQL Structured Query Language
SRL Subrate Data Link; Structural Return Loss
SRM Subrate Multiplexer
SRS Subrate Switch
SS Spread Spectrum; Signaling System
SSB Single Sideband Modulation; Star-Star Bus
SSCI Small Computer Systems Interface
SSCQE Single Stimulus Continuous Quality Evaluation
SSOP Shrink Small Outline Package
SSP Service Switching Point
SSU System Synchronization Unit
ST Stuffing Table
STB Set Top Box
STC System Time Clock
STDB Serial Time Distribution Bus
STE Special Test Equipment
STERN System de Television Radio Numerique
STL Studio to Transmitter Link
STM-1 Synchronous Transmission Mode (155.52 Mbit/s)
STM-16 Synchronous Transmission Mode (2.488 Gbit/s)
STM-4 Synchronous Transmission Mode (622.08 Mbit/s)
STP Signaling Transfer Point
STS Synchronous Transport Signal
STS1 51.84 Mb/s (SONET)
STS3c 155 Mb/s (SONET)
STV Subscription Television
SVC Switched Virtual Circuit
S-Video Separate Video - video interface carrying separate, synchronised signals for luminance (Y)  and chrominance (C) information
SWR Standing Wave Ratio
T1 1.544 Mb/s
T3 44.376 Mb/s
TA Terminal Adaptor; Technical Advisory, Temporal Activity
TAB Tape Automated Bonding
TAP Transmission Access Processor, Transmission Access Platform
TBD To Be Defined
TC Transmission Convergence
TCC Telephone Coordinating Circuit
TCM Trellis Coded Modulation
TCP/IP Transmission Control Protocol/Internet Protocol
TCS Transport Control System
TDL Tapped Delay Line
TDM Time Division Multiplexing
TDMA Time Division Multiple Access
TDR Time Domain Reflectometer
TDT Time and Date Table (multiplex) (part of SI); Transparent Digital Modulation
TE Transverse Electric
TEM Transverse Electro-Magnetic
TETRA Terrestrial Trunked Radio
TFT Thin Film Transistor
TFTP Trivial File Transfer Protocol
THz Terahertz
TI Terrestrial Interference
TIM Telephone Interface Module
TIPHON Telecommunications and Internet Protocol Harmonization Over Networks
TIRP T-Link Integrated Receiver
T-Link Transport Link (Data Rate: 270 Mbps)
TLP Transmission Level Point
TM Transverse Magnetic
TMC Traffic Message Channel
TMDS Transition Minimized Differential Signalling
TMN Telecommunications Management Network
TMUX T-Link Multiplexer
TNC Threaded Neil-Councilman Connector
TOT Time Offset Table (part of SI)
TPS Transmission-Parameter Signalling
TR Tip Return; Technical Reference
TS Transport Stream
TS0 Time Slot Zero
TSI Time Slot Interchange
TSM Timeslot 24 Signalling Module
TSOP Thin Small Outline Package
TTC Telephony Transport Converter
TTC&M Telemetry,Tracking, Control and Monitoring function
TTL Transistor-Transistor Logic
TTY TeleTYpe
TV Television
TVRO Television Receive Only
TWTA Travelling Wave Tube Amplifier
TX Transmitter / Telex
UAR Universal Asynchronous Receiver
UART Universal Asynchronous Receiver / Transmitter
UBR Unspecified Bit Rate
UCS Universal Card Slot
UDP Universal Distribution Panel; User Datagram Protocol
UDP/IP User Datagram Protocol / Internet Protocol
UEP Unequal Error Protection
UHF Ultra High Frequency
UL Underwriters Laboratories
ULSI Ultra Large Scale Integration
UMS Umbrella Management System
UMTS Universal Mobile Telecommunications System (3G)
UNI User Network Interface
UPS Uninterruptible Power Supply
UPT Universal Personal Telecommunications
UQM Uplink Quality Monitor
URL Universal Resource Locator
USB Upper Sideband; Universal Serial Bus
USP Universal Services Processor
UTOPIA Universal Test and Operations Interface
UTP Unshielded Twisted Pair
V0P Velocity Of Propagation
VAC Voltage Alternating Current
VAD Video Adaptor Module (Digital)
VADIS Video-Audio Digital Interactive System
VAM Video Adaptor Module
VAN Value Added Network
VANC Voice Activated Network Control
VAPN Virtual Access to Private Networks
VBI Vertical Blanking Interval
VBN Virtual Backbone Network
VBR Variable Bit Rate
VC Virtual Channel
VCB Voice Conference Bridge
VCI Virtual Channel Identifier
VCM Video Compression Module
VCO Voltage-Controlled Oscillator
VCR Video Cassette Recorder
VCXO Voltage Controlled Crystal Oscillator
VDB Video Distribution Bus
VDC Voltage Direct Current
VDE Verband Deutscher Elektrotechniker
VDSL Very high data rate Digital Subscriber Line
VDT Video Dial Tone
VDU Visual Display Unit
VF Voice Frequency
VGA Video Graphics Adaptor
VHF Very High Frequency
VI Virtual Instrument
VIRS Vertical Interval Reference test Signal
VITC Vertical Interval Time Code
VITS Vertical Interval Test Signal
VLC Variable Length Coding
VLF Very Low Frequency
VLIW Very Long Instruction Word
VLSI Very Large Scale Integration
VMEbus VERSAbus-E (IEEE-1014) ( Eurocard )
VOD Video On Demand
VoIP Voice over Internet Protocol
VP Virtual Path
VPI Virtual Path Identifier
VPN Virtual Private Networks
VQFP Very Thin Quad Pack
VR Velocity Ratio 
VRQAM Variable Rate QAM
VRU Voice Response Unit
VSAT Very Small Aperture Terminal
VSB Vestigial Sideband
VSN Virtual Switched Network
VSWR Voltage Standing Wave Ratio
VTR Video Tape Recorder
VU Volume Unit
VXIbus VMEbus Extensions for Instruments
WAIS Wide Area Information Servers
WAN Wide Area Network
WAP Wireless Application Protocol
WARC World Administrative Radio Conference
WATS Wide Area Telecommunications Service
WDM Wavelength Division Multiplex
WEEE Waste from Electrical and Electronic Equipment
WiFi Wireless Fidelity 
WK Working Key
WMATV Wireless Master Antenna Television System
WPBX Wireless Private Branch Exchange
WSI Wafer Scale Integration
WWW World Wide Web
XMOD Cross Modulation
XTP Express Transfer Protocol
Y/C Video interface carrying separate, synchronised signals for luminance (Y)  and chrominance (C) information
YAG Yttrium Aluminium Garnet
YCP Yellow Condition Propagation
ZCO Zero Crossing Origin