Page 5-58 Publication No. 150-041118
Section 5 – Configuration and Programming Rev. A
Sep 2001
Glossary
AM – Acronym for “Amplitude Modulation”. In this type of modulation, the amplitude of the signal is varied in
proportion to the voice or data input signal. The signal quality can be severely degraded because of lightning
or man made electrical noise. AM is only used in the frequency ranges 108 to 152 MHz and 225 to 400
MHz. All air traffic control functions use AM modulation.
Audio Phase – The RT-5000 can invert the phase of the audio signal during transmit or receive. This is sometimes
necessary for DPL systems to work.
Bandwidth – A term used to describe the amount of frequency a channel has to transmit a signal. Two of the most
common FM channel bandwidths are 12.5 kHz (Narrow) and 25 kHz (Standard). Some special signals, such
as military encryption, work best when using 35 kHz (Wide) or 70 kHz (Extra-wide) channels. All of these
bandwidths are available in the RT-5000.
Channel – A group of radio characteristics, such as receive & transmit frequencies, modulation, power levels, etc.
CMC – An acronym for Communication Management Controller. The C-5000 is a CMC.
CTCSS – Acronym for “Continuous Coded Squelch System”.
DCS – Acronym for “Digital Coded Squelch”
DES – Acronym for “Digital Encryption Standard”. This is an algorithm by which signals are encrypted.
Deviation – The amount of peak change the RF signal varies from the carrier in proportion to the amplitude of the
voice signal.
DPL – Acronym for “Digital Private Line”. Also known as DCS.
DTMF – Dual Tone Multiple Frequency. On a telephone keypad, each row and column have unique audio tones
that are sent when a button is pushed. At the receiver, a decoder listens for a row tone and a column tone and
can determine from that, which button has been pushed.
Direct – Also known as simplex, car-to-car, and talk-around. This mode of operation allows you to bypass the
repeater and talk directly to another radio. Transmit and receive frequencies are the same.
Encryption – Method by which a signal is “scrambled” so that other listeners cannot understand what is being
transmitted.
Encryption Key – When encrypting a transmission, the algorithm used to scramble the information requires both
the transmitting and receiving devices to have a number. This number is called an Encryption Key. Some
systems are limited to one key and others are capable of having multiple keys.
Flexcomm I – First generation of Flexcomm control heads and transceivers. This includes the C-1000 control head
and RT-30, RT-138(F), RT-450, RT-406F transceivers.
Flexcomm II – Second generation of Flexcomm control heads and transceivers. This includes the C-5000 control
head and RT-5000 multi-band transceiver.
FM – Acronym for “Frequency Modulation”. In this type of modulation, the frequency of the signal is varied from
its center point in proportion to the amplitude of the voice or data signal. Most importantly, this type of
modulation is not affected by lightning or other atmospheric noise.
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