Codan Radio P25 Training Guide - Manual (Page 109)

P25 RADIO SYSTEMS | TRAINING GUIDE
Chapter 9: P25 Glossary of Terms Page 101
Channel Spacing
Typically measured in kilohertz from the
center of one channel to the center of
the next-adjacent-channel. May, or may
not, be identical to bandwidth.
C/I
Abbreviation for “Carrier to Interference”
signal ratio.
CM
Abbreviation for a “Circuit Merit” A
delivered voice quality test and rating
strategy
CODEC
A COder-DECoder device (analog to
digital voice conversion).
Common Air Interface (CAI)
A radio to radio signal path defi ned in
terms of Access Method, Modulation
Scheme, Vocoding Method, Channel
Data Rate and Channel Data Format.
Common channel signaling (CCS)
A signaling method using one of the
channels on a multichannel network
for the control, accounting and
management of traffi c on all of the
channels of the network.
Console
A sub-system comprised of one or more
elements from a single manufacturer
that is the device(s) which allows a
person(s) to effectively and effi ciently
use and control the capabilities and the
functions of the radio system(s) to which
it is attached.
Covert
Adjective used to describe undercover
operations by government agents.
“Covert” communications are generally
encrypted.
CQPSK
The acronym for a QPSK IQ transmitter
which uses QPSK-C modulation to work
with a CFDD compatible receiver.
CRC
Cyclic Redundancy Checksum for data
error detection.
CSMA/CD
Abbreviation for “Carrier Sense, Multiple
Access” with “Collision Detection.” It is a
multi-access technique in which stations
listen before transmitting. A transmitting
station detecting a collision aborts its
transmission.
CTCSS
Abbreviation for “Continuous Tone-
Controlled Squelch System.”
CVSD
Abbreviation for “Continuously Variable
Slope Delta” modulation technique. A
type of delta modulation in which the
size of the steps of the approximated
signal is progressively increased or
decreased as required to make the
approximated signal closely match the
input analog signal.
DAM
Abbreviation for a “Diagnostic
Acceptance Measure.” An audio
acceptability test.
DCE
Abbreviation for “Data Circuit
terminating Equipment” through which
the DTE is connected to a network.
DCPSK
Abbreviation for the “Differential
Coherent Phase Shift Keying”
modulation technique. A method of
encoding information in terms of phase
changes, rather than absolute phases,
and detected by comparing phases of
adjacent BITs.
DCT
Abbreviation for “Discrete Cosine
Transform” a technique used in
vocoding.
Deadlock
A situation in which traffi c ceases to fl ow
and throughput drops to Zero.
De-Key
Turn the transmitter off (release the
Push-to-Talk switch).