Glossary of Terms

ACP – Adjacent Channel Power

 

APCO International—Association of Public-Safety Communications Officials - International, Inc.

 

ARQ – Automatic Retry Request (to retry corrupted packets)

 

BER-Bit Error Rate

 

BR—Base Radio (A reference designating a base station)

 

C4FM—Compatible four-level frequency modulation

 

CAI- Common Air Interface

 

CQPSK – Compatible quadrature phase shift keying

 

CRC—Cyclic Redundancy Checksum (For data error detection)

 

DES – Data Encryption Standard

 

DiBit—Two bits grouped together to represent a four-level symbol

 

DPSK – Differential Phase-Shift Keying

 

ES—Encryption Synchronization (Information embedded in voice)

 

FDMA – Frequency Division Multiple Access

 

FS—Frame Synchronization (Marks the first information bit)

 

FSK—Frequency Shift Keying

 

Golay—A standard error correction code

 

Hex Bit—Six bits grouped together to represent a Reed-Solomon code symbol

 

IMBE vocoder -- Improved Multiband Excitation vocoder, providing 4400 bits/s of digitized voice

 

IQ – In-phase / quadrature

 

KID—Key Identifier (Indicates the encryption key for the message)

 

LC—Link Control (Information embedded in voice)

 

LLC—Logical Link Control (Sub-layer of the OSI Data Link Layer)

 

LSD—Low Speed Data (Data embedded in voice)

 

MAC—Media Access Control (Sub-layer of the OSI Data Link Layer)

 

MI—Message Indicator (To initialize encryption)

 

MSK – Minimum-shift keying

 

NASTD— International and the National Association of State Telecommunications Directors

 

Project 25 Phase I – The backwards compatible migration path to full Project 25 specification that specifies a 12.5 kHz bandwidth using C4FM modulation

 

Project 25 Phase II – The backwards compatible migration path to full Project 25 specification that specifies a 6.25 kHz bandwidth using CQPSK modulation

 

NID—Network Identifier (The code word following the frame link)

 

Octal—Base 8 notation for numbers (also called radix 8)

 

Octet—Eight bits grouped together (Also called byte)

 

OSI—Open Systems Interconnection reference model

 

QPSK—Quadrature Phase Shift Keying modulation for data

 

QPSK-c—Compatible Quadrature Phase Shift Keying (Family of modulations)

 

RS—Reed-Solomon error connection code

 

SAP—Service Access Point (Where a network provides service)

 

STS – System to system, one of the proposed approaches to interoperability testing

 

TDMA – Time Division Multiple Access

 

TETRA – Terrestrial Trunked Radio: An open digital trunked radio standard defined by the European Telecommunications Standards Institute

 

TIA – Telecommunications Industry Association

 

Type III Encryption—Type of encryption used for non-classified communications

 

Type IV Encryption—Type of encryption used for export

 

UM—Common Air Interface reference point