20-428 Owner’s Manual
Page 36 of 50
To receive trunking signals, you must store all the trunking control frequencies for Motorola
systems or all the trunking group frequencies for EDACS and LTR in one bank (see “Storing Known
Frequencies into Channels”) and input ID codes in the ID memory (see “Storing Talk Group IDs”).
Your PRO-2055 automatically calculates Motorola voice channel frequencies when it decodes the
control channel. This eliminates the need to enter all the Motorola group frequencies.
The control channels are subject to change depending on the day. Therefore enter all the control
frequencies in the same bank. If you do not know which is the control channel, it is better to enter
all the system frequencies into the same bank.
When the scanner decodes the Motorola control channel and finds the voice channel, the scanner
displays the control channel memory location on the top line, the received frequency with VC (voice
channel) on the second line, the bank and control channel memory location number on the third line
and the Motorola ID number on the bottom line.
Note: To listen to the transmission, the mode of the programmed channel must be the same as that
of the trunking channel (MO, ED, or LT).
When an ID code is received, the ID list for the bank is searched, and if found, the text name stored
for the ID appears. If not found, scanning resumes immediately unless the bank is in open trunking
mode.
Notes:
•
There might be more than one talk group transmitting at a time in some Motorola trunking
systems. If you set the scanner to manually tune in Motorola trunking mode, you will hear the talk
group on that channel, but the display will alternate between all active IDs.
•
Frequency fleet map and talk group information are also widely available on the Internet (for
example, at www.trunkscanner.com).
In the past, groups that transmit frequently, such as police departments, could transmit on only a
few frequencies. This resulted in heavy traffic and often required 2-way radio users to wait for a
specific frequency to clear before transmitting. Trunked systems allow more groups of 2-way radio
users to use fewer frequencies. Instead of selecting a specific frequency to transmit on, a trunked
system chooses one of several frequencies when the 2-way radio user transmits. The system
automatically transmits the call on that frequency, and also sends a code that identifies that 2-way
radio user’s transmission on a control channel.
Your scanner lets you easily hear both the call and response transmissions for that 2-way radio user
and therefore follow the conversation. For EDACS and Motorola (above 406 MHz range), the
scanner monitors the control channel between each transmission to identify talk groups. For some
Motorola (under 512 MHz range) and LTR systems, the scanner uses the subaudible data sent with
