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

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