C-5000 Pilot’s Guide
Publication No. 150-041103 Page 35 of 51
Rev. C C-5000 Pilot’s Guide
Nov 2013
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.
Guard Receiver – Second receiver added to the transceiver to monitor a specific frequency. Some
common “guard” frequencies are 121.5, 243, Marine channel 16, and Marine channel 70. However,
this optional function can also be used to monitor a dispatch channel, or an important tactical
frequency. Some Guard receivers have a single frequency that is set in hardware. Other options,
available only in the RT-5000, are a programmable dual channel receiver and a multi-band
P25/Trunking compatible unit.
IF Injection – In a superhetrodyne receiver, high frequency signals are progressively lowered in
frequency until only the audio is left. This is done by multiplying the RF Signal by a sinewave either
above or below the RF carrier. Mathematically this results in an “Intermediate Frequency” (IF)
frequency that is the sum and difference of the two signals. The RT-5000 has the capability of
having either High (Above) or Low (Below) the signal frequency. What this means is if you have a
signal interfering with the desired signal, sometimes the interference can be eliminated by switching
either the 2
nd
or 3
rd
injection setting.
Interoperability – The ability for different radio systems to communicate with each other directly. For
example, when one manufacturer’s radio products will communicate with another’s, they are said to be
“Interoperable”.
ITM – “Internal Transceiver Module”. This is the module that is physically placed in the Guard Receiver
slot in the RT-5000. This is the part of the radio that can perform P25, encryption, and Motorola Trunking.
Each ITM covers a specific frequency band – 138-174, 403-470, 450-520, and 800 MHz. Up to two ITM’s
can be put into one RT-5000 however one must be below 400 MHz and one above 400 MHz.
KEYMAT – Another name for encryption key.
KVL – Acronym for Key Variable Loader. It is a Motorola product for loading encryption keys into an
encryption capable radio.
Main Receiver – Full function receiver located in every transceiver.
Manual Channel – A special preset channel that allows the operator to manipulate channel information
“on the fly” without going into programming mode. On the C-5000 this special channel is labeled
“..M” and is located at channel 0.
MODE 1 – Operational mode of the C-5000/RT-5000 system where the operator does not know there is a
main and guard located in the transceiver. This simplifies the user interface dramatically.
However, only one receiver, the main or the ITM module in the Guard is in operation at one time so
only one channel is monitored.
MODE 2 – Operational mode of the C-5000/RT-5000 system where the main and guard receiver are both
monitoring frequencies at the same time. The user interface is more complex in that the user must
select using the silver “soft” buttons on the C-5000 which channel to display and transmit on.
OTAR – Acronym for “Over The Air Re-key”. Method by which the Encryption Key is transmitted over the
radio channel, hence “over the air”.
P25 – Digital Modulation Standard.
Page – The contents of the display. Sometimes called a screen or view.
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