2 GLOSSARY OF TERMS
A summary of common radio terms and some other terms used in this document, and
their meanings, are given below.
Alert Tones
These are tones emitted by the transceiver to indicate an
invalid entry or operator error.
Current Phonebook
Entry
This is the entry the Phonebook Screen would display if
currently called upon.
CTCSS
Continuous Tone Coded Squelch System. A continuous tone
(lower than the audio range of the receiver) is modulated onto
the carrier as well as other signalling or voice traffic. Only
receivers that have been programmed to recognise the same
CTCSS tone are able to receive the transmissions, since the
squelch of receivers looking for different CTCSS tones
prevents the audio from being heard. This provides a simple
method of sending messages to selected receivers and allows
several different networks to use the same frequency. CTCSS is
also known as Tone Lock or Tone Squelch.
DCS
Digital Coded Squelch system is based on sending a
continuous stream of binary code words using low deviation,
direct frequency shift keying. Only receivers which have been
programmed to recognise the same DCS sequence are able to
open their squelch and receive the associated speech
transmissions. This provides a simple method of sending
messages to selected receivers only and allows several
different networks to use the same frequency. DCS is also
known as CDCSS.
DTMF
Dual Tone Multi-Frequency signalling. Used to dial into
Telephone networks using tone dialling.
IECEx Scheme
The International Electrotechnical Commission Scheme for
Certification to Standards Relating to Equipment for use in
Explosive Atmospheres
Muted
Audio cannot be heard from the loudspeaker.
MPT1327
A signalling standard for Trunked Private Land Mobile Radio
Systems. Defined for systems in the UK but also used outside
the UK. Issued January 1988.
Multiax
CTCSS based multi channel sharing system.
Network
The System Infrastructure, e.g. a Trunked MPT1327 Network
or conventional repeater system.
PTT
Press To Talk. This is the term given to the operator’s key
normally used to commence transmitting a message.
Selcall
Selective Calling - a system of signalling which allows ‘dialling
Doc Number:
TNM-U-E-0089 ISSUE 2.2
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