Κεντρική

a

atto (10^-18)

angstrom

A

ampere

AAR

automatic alternate routing

AARTS

automatic audio remote test set

ABCA

American, British, Canadian, Australian [armies]

ac

alternating current

ACA

automatic circuit assurance

ACC

automatic callback calling

ACD

automatic call distributor

ac-dc

alternating current - direct current

ACK

acknowledge character

ACTS

Advanced Communications Technology Satellite

ACU

automatic calling unit

A-D

analog-to-digital

ADC

analog-to-digital converter
analog-to-digital conversion

ADCCP

Advanced Data Communication Control Procedures

ADH

automatic data handling

ADP

automatic data processing

ADPCM

adaptive differential pulse-code modulation

ADPE

automatic data processing equipment

ADPSSO

automatic data processing system security officer

ADU

automatic dialing unit

ADX

automatic data exchange

AECS

Aeronautical Emergency Communications System [Plan]

AF

audio frequency

AFC

area frequency coordinator
automatic frequency control

AFNOR

Association Français Normal

AFRS

Armed Forces Radio Service

AGC

automatic gain control

AGE

aerospace ground equipment

AI

artificial intelligence

AIG

address indicator group
address indicating group

AIM

amplitude intensity modulation

AIN

advanced intelligent network

AIOD

automatic identified outward dialing

AIS

automated information system

ASIC

application-specific integrated circuits

AJ

anti-jamming

ALC

automatic level control
automatic load control

ALE

automatic link establishment

ALU

arithmetic and logic unit

A/m

amperes per meter

AM

amplitude modulation

AMA

automatic message accounting

AMC

administrative management complex

AME

amplitude modulation equivalent
automatic message exchange

AMI

alternate mark inversion [signal]

AM/PM/VSB

amplitude modulation/phase modulation/vestigial sideband

AMPS

automatic message processing system

AMPSSO

automated message processing system security officer

AMSC

American Mobile Satellite Corporation

AMTS

automated maritime telecommunications system

ANI

automatic number identification

ANL

automatic noise limiter

ANMCC

Alternate National Military Command Center

ANS

American National Standard

ANSI

American National Standards Institute

AP

anomalous propagation

APC

adaptive predictive coding

APD, apd, a.p.d.

avalanche photodiode

API

application program interface

APL

average picture level

APK

amplitude phase-shift keying

ARP

address resolution protocol

ARPA

Advanced Research Projects Agency [now DARPA]

ARPANET

Advanced Research Projects Agency Network

ARQ

automatic repeat-request

ARS

automatic route selection

ARSR

air route surveillance radar

ARU

audio response unit

ASC

AUTODIN Switching Center

ASCII

American Standard Code for Information Interchange

ASN.1

abstract syntax notation one

ASP

Aggregated Switch Procurement
adjunct service point

ASR

automatic send and receive
airport surveillance radar

AT

access tandem

ATACS

Army Tactical Communications System

ATB

all trunks busy

ATCRBS

air traffic control radar beacon system

ATDM

asynchronous time-division multiplexing

ATE

automatic test equipment

ATM

asynchronous transfer mode

ATV

advanced television

au

astronomical unit

AUI

attachment unit interface

AUTODIN

Automatic Digital Network

AUTOSEVOCOM

Automatic Secure Voice Communications Network

AUTOVON

Automatic Voice Network

AVD

alternate voice/data

AWG

American wire gauge

AWGN

additive white Gaussian noise

AZ

azimuth

b

bit

B

bel
byte

balun

balanced to unbalanced

basecom

base communications

BASIC

beginners' all-purpose symbolic instruction code

BCC

block check character

BCD

binary-coded decimal
binary-coded decimal notation

BCI

bit-count integrity

Bd

baud

B8ZS

bipolar with eight-zero substitution

bell

BEL character

BER

bit error ratio

BERT

bit error ratio tester

BETRS

basic exchange telecommunications radio service

BEX

broadband exchange

BIH

International Time Bureau

B-ISDN

broadband ISDN

bi-sync

binary synchronous [communication]

bit

binary digit

BIT

built-in test

BITE

built-in test equipment

BIU

bus interface unit

BNF

Backus Naur form

BOC

Bell Operating Company

BPSK

binary phase-shift keying

bpi

bits per inch
bytes per inch

b/s

bits per second

b/in

bits per inch

BPSK

binary phase-shift keying

BR

bit rate

BRI

basic rate interface

BSA

basic serving arrangement

BSE

basic service element

BSI

British Standards Institution

B6ZS

bipolar with six-zero substitution

B3ZS

bipolar with three-zero substitution

BTN

billing telephone number

BW

bandwidth

c

centi (10^-2)

CACS

centralized alarm control system

CAM

computer-aided manufacturing

CAMA

centralized automatic message accounting

CAN

cancel character

CAP

competitive access provider
customer administration panel

CARS

cable television relay service [station]

CAS

centralized attendant services

CASE

computer-aided software engineering
computer aided system engineering
computer-assisted software engineering

CATV

cable TV
cable television
community antenna television

CBX

computer branch exchange

C²

command and control

C³

command, control and communications

C³CM

C³countermeasures

C³I

command, control, communications and intelligence

CCA

carrier-controlled approach

CCD

charge-coupled device

CCH

connections per circuit hour

CCIF

International Telephone Consultative Committee [a predecessor to the CCITT]

CCIR

International Radio Consultative Committee

CCIS

common-channel interoffice signaling

CCIT

International Telegraph Consultative Committee [a predecessor to the CCITT]

CCITT

International Telegraph and Telephone Consultative Committee {now ITU-T}

CCL

continuous communications link

CCS

hundred call-seconds

CCSA

common control switching arrangement

CCTV

closed-circuit television

CCW

cable cutoff wavelength

cd

candela

CD

collision detection, compact disk

CDF

combined distribution frame
cumulative distribution function

CDMA

code-division multiple access

CDPSK

coherent differential phase-shift keying

CDR

call detail recording

CD ROM

compact disk read-only memory

CDT

control data terminal

CDU

central display unit

C-E

communications-electronics

CEI

comparably efficient interconnection

CELP

code-excited linear prediction

CEP

circular error probable

CFE

contractor-furnished equipment

cgs

centimeter-gram-second

ChR

channel reliability

CIAS

circuit inventory and analysis system

CIC

content indicator code

CIF

common intermediate format

CIFAX

ciphered facsimile

CINC

commander-in-chief

ciphony

ciphered telephony

CiR

circuit reliability

C/kT

carrier-to-receiver noise density

CLASS

custom local area signaling service

cm

centimeter

CMI

coded mark inversion

CMIP

Common Management Information Protocol

CMIS

common management information service

CMOS

complementary metal oxide substrate

CMRR

common-mode rejection ratio

CNR

carrier-to-noise ratio
combat-net radio

CNS

complementary network service

C.O.

central office

COAM

customer owned and maintained equipment

coax

coaxial cable

COBOL

common business oriented language

codec

coder-decoder

COG

centralized ordering group

COMINT

communications intelligence

COMJAM

communications jamming

compandor

compressor-expander

COMPUSEC

computer security

COMSAT

Communications Satellite Corporation

COMSEC

communications security

CONEX

connectivity exchange

CONUS

Continental United States

COP

Committee of Principals

COR

Council of Representatives

COT

customer office terminal

CPAS

cellular priority access services

CPE

customer premises equipment

cpi

characters per inch

cpm

counts per minute

cps

characters per second
cycles per second [deprecated]

CPU

central processing unit
communications processor unit

CR

channel reliability
circuit reliability

CRC

cyclic redundancy check

CRITICOM

Critical Intelligence Communications

CROM

control read-only memory

CRT

cathode ray tube

c/s

cycles per second [deprecated]

CSA

Canadian Standards Association

CSC

circuit-switching center
common signaling channel

CSMA

carrier sense multiple access

CSMA/CA

carrier sense multiple access with collision avoidance

CSMA/CD

carrier sense multiple access with collision detection

CSU

channel service unit
circuit switching unit
customer service unit

CTS

clear to send

CTX

Centrex ® [service]
clear to transmit

CVD

chemical vapor deposition

CVSD

continuously variable slope delta [modulation]

cw

carrier wave
composite wave
continuous wave

CX

composite signaling

cxr

carrier

D*

specific detectivity

d

deci (10¹)

D()

dispersion coefficient

da

deka (10)

D-A

digital-to-analog
digital-to-analog converter

D/L

downlink

DACS

digital access and cross-connect system

DAMA

demand assignment multiple access

DARPA

Defense Advanced Research Projects Agency [formerly ARPA]

dB

decibel

dBa

decibels adjusted

dBa(F1A)

noise power measured by a set with F1A-line weighting

dBa(HA1)

noise power measured by a set with HA1-receiver weighting

dBa0

noise power measured at zero transmission level point

dBc

dB relative to carrier power

dBm

dB referred to 1 milliwatt

dBm(psoph)

noise power in dBm measured by a set with psophometric weighting

DBMS

database management system

dBmV

dB referred to 1 millivolt across 75 ohms

dBm0

noise power in dBm referred to or measured at 0TLP

dBm0p

noise power in dBm0 measured by a psophometric or noise measuring set having psophometric weighting

dBr

power difference in dB between any point and a reference point

dBrn

dB above reference noise

dBrnC

noise power in dBrn measured by a set with C-message weighting

dBrnC0

noise power in dBrnC referred to or measured at 0TLP

dBrn(f₁-f₂)

flat noise power in dBrn

dBrn(144-line)

noise power in dBrn measured by a set with 144-line weighting

dBv

dB relative to 1 V (volt) peak-to-peak

dBW

dB referred to 1 W (watt)

dBx

dB above reference coupling

dc

direct current

DCA

Defense Communications Agency (now DISA)

DCE

data circuit-terminating equipment

DCL

direct communications link

DCPSK

differentially coherent phase-shift keying

DCS

Defense Communications System

DCTN

Defense Commercial Telecommunications Network

DCWV

direct-current working volts

DDD

direct distance dialing

DDN

Defense Data Network

DDS

digital data service

DEL

delete character

demarc

demarcation point

demux

demultiplex
demultiplexer
demultiplexing

dequeue

double-ended queue

DES

Data Encryption Standard

detem

detector/emitter

DFSK

double-frequency shift keying

DIA

Defense Intelligence Agency

DID

direct inward dialing

DIN

Deutsches Institut fόr Normung

DIP

dual in-line package

DISA

Defense Information Systems Agency {formerly DCA}

DISC

disconnect command

DISN

Defense Information System Network

DISNET

Defense Integrated Secure Network

DLA

Defense Logistic Agency

DLC

digital loop carrier

DLE

data link escape character

DM

delta modulation

DMA

Defense Mapping Agency
direct memory access

DME

distance measuring equipment

DMS

Defense Message System

DNA

Defense Nuclear Agency

DNIC

data network identification code

DNPA

data numbering plan area

DNS

Domain Name System

DO

design objective

DoC

Department of Commerce

DOD

Department of Defense
direct outward dialing

DODD

Department of Defense Directive

DODISS

Department of Defense Index of Specifications and Standards

DOD-STD

Department of Defense Standard

DOS

Department of State

DPCM

differential pulse-code modulation

DPSK

differential phase-shift keying

DQDB

distributed-queue dual-bus [network]

DRAM

dynamic random access memory

DRSI

destination station routing indicator

DS

digital signal
direct support

DS0

digital signal 0

DS1

digital signal 1

DS1C

digital signal 1C

DS2

digital signal 2

DS3

digital signal 3

DS4

digital signal 4

DSA

dial service assistance

DSB

double-sideband [transmission]
Defense Science Board

DSB-RC

double-sideband reduced carrier transmission

DSB-SC

double-sideband suppressed-carrier transmission

DSC

digital selective calling

DSCS

Defense Satellite Communications System

DSE

data switching exchange

DSI

digital speech interpolation

DSL

digital subscriber line

DSN

Defense Switched Network

DSR

data signaling rate

DSS

direct station selection

DSSCS

Defense Special Service Communications System

DSTE

data subscriber terminal equipment

DSU

data service unit

DTE

data terminal equipment

DTMF

dual-tone multifrequency [signaling]

DTG

date-time group

DTN

data transmission network

DTS

Diplomatic Telecommunications Service

DTU

data transfer unit
data tape unit
digital transmission unit
direct to user

DVL

direct voice link

DX signaling

direct current signaling
duplex signaling

E

exa (10¹⁸)

E-MAIL, e-mail

electronic mail

EAS

extended area service

EBCDIC

extended binary coded decimal interchange code

E_b/N₀

signal energy per bit per hertz of thermal noise

EBO

embedded base organization

EBS

Emergency Broadcast System

EBX

electronic branch exchange

EC

Earth coverage
Earth curvature

ECC

electronically controlled coupling
enhance call completion

ECCM

electronic counter-countermeasures

ECM

electronic countermeasures

EDC

error detection and correction

EDI

electronic data interchange

EDTV

extended-definition television

EHF

extremely high frequency

EIA

Electronic Industries Association

eirp

effective isotropically radiated power
equivalent isotopically radiated power

EIS

Emergency Information System

el

elevation

ELECTRO-OPTINT

electro-optical intelligence

ELF

extremely low frequency

ELINT

electronics intelligence
electromagnetic intelligence

ELSEC

electronics security

ELT

emergency locator transmitter

EMC

electromagnetic compatibility

EMCON

emission control

EMD

equilibrium mode distribution

EME

electromagnetic environment

emf

electromotive force

EMI

electromagnetic interference
electromagnetic interference control

EMP

electromagnetic pulse

EMR

electromagnetic radiation

EMR hazards

electromagnetic radiation hazards

e.m.r.p.

effective monopole radiated power
equivalent monopole radiated power

EMS

electronic message system

EMSEC

emanations security

emu

electromagnetic unit

EMV

electromagnetic vulnerability

EMW

electromagnetic warfare
electromagnetic wave

ENQ

enquiry character

EO

end office

E.O.

Executive Order

EOD

end of data

EOF

end of file

EOL

end of line

EOM

end of message

EOP

end of program
end output

EOS

end-of-selection character

EOT

end-of-transmission character
end of tape

EOW

engineering orderwire

EPROM

erasable programmable read-only memory

EPSCS

enhanced private switched communications system

ERL

echo return loss

ERLINK

emergency response link

ERP, e.r.p.

effective radiated power

ES

end system
expert system

ESC

escape character
enhanced satellite capability

ESF

extended superframe

ESM

electronic warfare support measures

ESP

enhanced service provider

ESS

electronic switching system

ETB

end-of-transmission-block character

ETX

end-of-text character

EW

electronic warfare

EXCSA

Exchange Carriers Standards Association

f

femto (10^-15)

f

frequency

FAA

Federal Aviation Administration

FAQ file

Frequently Asked Questions file

FAX

facsimile

FC

functional component

FCC

Federal Communications Commission

FCS

frame check sequence

FDDI

fiber distributed data interface

FDDI-2

fiber distributed data interface-2

FDHM

full duration at half maximum

FDM

frequency-division multiplexing

FDMA

frequency-division multiple access

FDX

full duplex

FEC

forward error correction

FECC

Federal Emergency Communications Coordinators

FED-STD

Federal Standard

FEMA

Federal Emergency Management Agency

FEP

front-end processor

FET

field effect transistor

FIFO

first-in first-out

FIP

Federal Information Processing

FIPS

Federal Information Processing Standards

FIR

finite impulse response

FIRMR

Federal Information Resources Management Regulations

FISINT

foreign instrumentation signals intelligence

FLTSATCOM

Fleet Satellite Communications

flops

floating-point operations per second

FM

frequency modulation

FO

fiber optics

FOC

final operational capability
full operational capability

FOT

frequency of optimum traffic
frequency of optimum transmission

FPIS

forward propagation ionospheric scatter

ft/min

feet per minute

fps

foot-pound-second

FPS

frames per second
focus projection and scanning

FRP

Federal Response Plan

FSDPSK

filtered symmetric differential phase-shift keying

FSK

frequency-shift keying

FSS

fully separate subsidiary

FSTS

Federal Secure Telephone Service {no longer in operation}

FT

fiber optic T-carrier

FTAM

file transfer, access, and management

FTF

Federal Telecommunications Fund

ft/s

feet per second

FTS

Federal Telecommunications System

FTS2000

Federal Telecommunications System 2000

FTSC

Federal Telecommunications Standards Committee

FTP

file transfer protocol

FWHM

full width at half maximum

FX

fixed service
foreign exchange service

FYDP

Five Year Defense Plan

g

profile parameter

G

giga (10⁹)

GBH

group busy hour

GCT

Greenwich Civil Time

GDF

group distribution frame

GETS

Government Emergency Telecommunications Service

GFE

Government-furnished equipment

GGCL

government-to-government communications link

GHz

gigahertz

GII

Global Information Infrastructure

GMT

Greenwich Mean Time

GOS

grade of service

GOSIP

Government Open Systems Interconnection Profile

GSA

General Services Administration

GSTN

general switched telephone network

G/T

antenna gain-to-noise-temperature

GTP

Government Telecommunications Program

GTS

Government Telecommunications System

GUI

graphical user interface

h

hecto (10²)
hour
Planck's constant

HCS

hard clad silica [fiber]

HDLC

high-level data link control

HDTV

high-definition television

HDX

half-duplex [operation]

HE₁₁mode

the fundamental hybrid mode [of an optical fiber]

HEMP

high-altitude electromagnetic pulse

HERF

hazards of electromagnetic radiation to fuel

HERO

hazards of electromagnetic radiation to ordnance

HERP

hazards of electromagnetic radiation to personnel

HF

high frequency

HFDF

high-frequency distribution frame

HLL

high-level language

HPC

high probability of completion

HV

high voltage

Hz

hertz

IA

International Alphabet [CCITT]

I&C

installation and checkout

IC

integrated circuit

ICI

incoming call identification

ICNI

Integrated Communications, Navigation, and Identification

ICW

interrupted continuous wave

IDDD

International Direct Distance Dialing

IDF

intermediate distribution frame

IDN

integrated digital network

IDTV

improved-definition television

IEC

International Electrotechnical Commission

IEEE

Institute of Electrical and Electronics Engineers

IES

Industry Executive Subcommittee

IF

intermediate frequency

I/F

interface

IFF

identification, friend or foe

IFRB

International Frequency Registration Board (now Radio Regulations Board )

IFS

ionospheric forward scatter

IIR

infinite impulse response

IITF

Information Infrastructure Task Force

ILD

injection laser diode

ILS

instrument landing system

IM

intensity modulation
intermodulation

IMA

individual mobilization augmentee

I&M

installation and maintenance

IMD

intermodulation distortion

IMP

interface message processor

IN

intelligent network

IN/1, IN/1+, IN/2

intelligent network concepts

INFOSEC

information systems security

INS

inertial navigation system

INTELSAT

International Telecommunications Satellite Consortium

INWATS

Inward Wide-Area Telephone Service

I/O

input/output [device]

IOC

integrated optical circuit
initial operational capability
input-output controller

IP

Internet protocol
intelligent peripheral

IPA

intermediate power amplifier

IPC

information processing center

IPM

impulses per minute
interference prediction model
internal polarization modulation
interruptions per minute

in/s

inches per second

ips

interruptions per second

IPX

Internet Packet Exchange

IQF

intrinsic quality factor

IR

infrared

IRAC

Interdepartment Radio Advisory Committee

IRC

international record carrier
Interagency Radio Committee

ISB

independent-sideband [transmission]

ISDN

Integrated Services Digital Network

ISM

industrial, scientific, and medical (applications)

ISO

International Organization for Standardization

ITA

International Telegraph Alphabet

ITA-5

International Telegraph Alphabet Number 5

ITC

International Teletraffic Congress

ITS

Institute for Telecommunication Sciences

ITSO

International Telecommunications Satellite Organization

ITU

International Telecommunication Union

IVDT

integrated voice data terminal

IXC

interexchange carrier

JANAP

Joint Army-Navy-Air Force Publication(s)

JCS

Joint Chiefs of Staff

JPL

Jet Propulsion Laboratory

JSC

Joint Steering Committee [now JTSSG]
Joint Spectrum Center

JTC³A

Joint Tactical Command, Control and Communications Agency

JTIDS

Joint Tactical Information Distribution System

JTRB

Joint Telecommunications Resources Board

JTSSG

Joint Telecommunications Standards Steering Group [formerly JSC]

JWID

Joint Warrior Interoperability Demonstration

k

kilo (10³)
Boltzmann's constant

K

coefficient of absorption
kelvin

KDC

key distribution center

KDR

keyboard data recorder

KDT

keyboard display terminal

kg

kilogram

kg•m•s

kilogram-meter-second

kHz

kilohertz

km

kilometer

k , k

kilohm

KSR

keyboard send/receive device

kT

noise power density

KTS

key telephone system

KTU

key telephone unit

wavelength

_CO

cutoff wavelength

LAN

local area network

LANTFLT

Atlantic Fleet

LAP-B

Data Link Layer protocol [CCITT Recommendation X.25 (1989)]

LAP-D

link access procedure D

laser

light amplification by stimulated emission of radiation

LASINT

laser intelligence

LATA

local access and transport area

LBO

line buildout

LC

limited capability

LCD

liquid crystal display

LD

long distance

LDM

limited distance modem

LEC

local exchange carrier

LED

light-emitting diode

LF

low frequency

LFB

look-ahead-for-busy [information]

LIFO

last-in first-out

LLC

logical link control [sublayer]

l/m

lines per minute

LMF

language media format

LMR

land mobile radio

LNA

launch numerical aperture

LOF

lowest operating frequency

loran

long-range aid to navigation system
long-range radio navigation
long-range radio aid to navigation system

LOS

line of sight
loss of signal

LP

linearly polarized [mode]
linear programming
linking protection
log-periodic [antenna]
log-periodic [array]

LPA

linear power amplifier

LPC

linear predictive coding

LPD

low probability of detection

LPI

low probability of interception

lpi

lines per inch

lpm

lines per minute

LP₀₁

the fundamental mode (of an optical fiber)

LQA

link quality analysis

LRC

longitudinal redundancy check

LSB

lower sideband, least significant bit

LSI

large scale integrated [circuit]
large scale integration
line status indication

LTC

line traffic coordinator

LUF

lowest usable high frequency

LULT

line-unit-line termination

LUNT

line-unit-network termination

LV

low voltage

m

meter
milli (10^-3)

M

mega (10⁶)

MAC

medium access control [sublayer]

MACOM

major command

MAN

metropolitan area network

MAP

manufacturers' automation protocol

maser

microwave amplification by the stimulated emission of radiation

M[]

material dispersion coefficient

MAU

medium access unit

MCC

maintenance control circuit

MCEB

Military Communications-Electronics Board

MCM

multicarrier modulation

MCS

Master Control System

MCW

modulated continuous wave

MCXO

microcomputer compensated crystal oscillator

MDF

main distribution frame

MDT

mean downtime

MEECN

Minimum Essential Emergency Communications Network

MERCAST

merchant-ship broadcast system

MF

medium frequency
multifrequency [signaling]

MFD

mode field diameter

MFJ

Modification of Final Judgment

MFSK

multiple frequency-shift keying

MHF

medium high frequency

MHS

message handling service
message handling system

MHz

megahertz

mi

mile

MIC

medium interface connector
microphone
microwave integrated circuit
minimum ignition current
monolithic integrated circuit
mutual interface chart

MILNET

military network

MIL-STD

Military Standard

min

minute

MIP

medium interface point

MIPS, mips

million instructions per second

MIS

management information system

MKS

meter-kilogram-second

MLPP

multilevel precedence and preemption

MMW

millimeter wave

modem

modulator-demodulator

modified AMI code

modified alternate mark inversion code

mol

mole

ms

millisecond (10^-3second)

MSB

most significant bit

MSK

minimum-shift keying

MTBF

mean time between failures

MTBM

mean time between maintenance

MTBO

mean time between outages

MTBPM

mean time between preventive maintenance

MTF

modulation transfer function

MTSO

mobile telephone switching office

MTSR

mean time to service restoral

MTTR

mean time to repair

micro (10^-6)

s

microsecond

MUF

maximum usable frequency

muldem

multiplexer/demultiplexer

MUX

multiplex
multiplexer

MUXing

multiplexing

mw

microwave

MWI

message waiting indicator

MWV

maximum working voltage

n

nano (10^-9)
refractive index

N₀

sea level refractivity
spectral noise density

NA

numerical aperture

NACSEM

National Communications Security Emanation Memorandum

NACSIM

National Communications Security Information Memorandum

NAK

negative-acknowledge character

NASA

National Aeronautics and Space Administration

NATA

North American Telecommunications Association

NATO

North Atlantic Treaty Organization

NAVSTAR-GPS

Navigational Satellite Timing and Ranging--Global Positioning System

NBFM

narrowband frequency modulation

NBH

network busy hour

NBRVF

narrowband radio voice frequency

NBS

National Bureau of Standards [now NIST]

NBSV

narrowband secure voice

NCA

National Command Authorities

NCC

National Coordinating Center for Telecommunications

NCS

National Communications System
net control station

NCSC

National Communications Security Committee

NDCS

network data control system

NDER

National Defense Executive Reserve

NEACP

National Emergency Airborne Command Post

NEC

National Electric Code ®

NEP

noise equivalent power

NES

noise equivalent signal

NF

noise figure

NFS

Network File System

NIC

network interface card

NICS

NATO Integrated Communications System

NID

network interface device
network inward dialing
network information database

NII

National Information Infrastructure

NIOD

network inward/outward dialing

NIST

National Institute of Standards and Technology [formerly NBS]

NIU

network interface unit

NLP

National Level Program

nm

nanometer

NMCS

National Military Command System

nmi

nautical mile

NOD

network outward dialing

Np

neper

NPA

numbering plan area

NPR

noise power ratio

NRI

net radio interface

NRM

network resource manager

NRRC

Nuclear Risk Reduction Center

NRZ

non-return-to-zero

NRZI

non-return-to-zero inverted

NRZ-M

non-return-to-zero mark

NRZ-S

non-return-to-zero space

NRZ1

non-return-to-zero, change on ones

NRZ-1

non-return-to-zero mark

ns

nanosecond

NSA

National Security Agency

NSC

National Security Council

NS/EP telecommunications

National Security or Emergency Preparedness telecommunications

NSTAC

National Security Telecommunications Advisory Committee

NTCN

National Telecommunications Coordinating Network

NTDS

Naval Tactical Data System

NTMS

National Telecommunications Management Structure

NT1

Network termination 1

NT2

Network termination 2

NTI

network terminating interface

NTIA

National Telecommunications and Information Administration

NTN

network terminal number

NTSC

National Television Standards Committee
National Television Standards Committee [standard]

NUL

null character

NVIS

near-vertical-incidence skywave

ohm

O&M

operations and maintenance

OC

operations center

OCC

other common carrier

OCR

optical character reader
optical character recognition

OCU

orderwire control unit

OCVCXO

oven controlled-voltage controlled crystal oscillator

OCXO

oven controlled crystal oscillator

OD

optical density
outside diameter

OFC

optical fiber, conductive

OFCP

optical fiber, conductive, plenum

OFCR

optical fiber, conductive, riser

OFN

optical fiber, nonconductive

OFNP

optical fiber, nonconductive, plenum

OFNR

optical fiber, nonconductive, riser

OMB

Office of Management and Budget

ONA

open network architecture

opm

operations per minute

OPMODEL

operations model

OPSEC

operations security

OPX

off-premises extension

OR

off-route service
off-route aeronautical mobile service

OSHA

Occupational Safety and Health Administration

OSI

open switching interval
Open Systems Interconnection

OSI-RM

Open Systems Interconnection--Reference Model

OSRI

originating stations routing indicator

OSSN

originating stations serial number

OTAM

over-the-air management of automated HF network nodes

OTAR

over-the-air rekeying

OTDR

optical time domain reflectometer
optical time domain reflectometry

OW

orderwire [circuit]

p

pico (10^-12)

P

peta (10¹⁵)

PABX

private automatic branch exchange

PAD

packet assembler/disassembler

PAL

phase alternation by line

PAL-M

phase alternation by line--modified

PAM

pulse-amplitude modulation

PAMA

pulse-address multiple access

p/a r

peak-to-average ratio

PAR

performance analysis and review

PARAMP

parametric amplifier

par meter

peak-to-average ratio meter

PAX

private automatic exchange

PBER

pseudo-bit-error-ratio

PBX

private branch exchange

PC

carrier power (of a radio transmitter)
personal computer

PCB

power circuit breaker
printed circuit board

PCM

pulse-code modulation
plug compatible module
process control module

PCS

Personal Communications Services
personal communications system
plastic-clad silica [fiber]

PCSR

parallel channels signaling rate

PD

photodetector

PDM

pulse delta modulation
pulse-duration modulation

PDN

public data network

PDS

protected distribution system
power distribution system
program data source

PDT

programmable data terminal

PDU

protocol data unit

PE

phase-encoded [recording]

PEP

peak envelope power (of a radio transmitter)

pF

picofarad

PF

power factor