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69
Beyond the Basics
trunking
how trunking works
The scanner tracks transmissions that use the Motorola
Type I and Type II (such as Smartnet and Privacy
Plus) and hybrid analog trunking systems, plus GE/
Ericsson (EDACS) and EF Johnson (LTR) type systems
extensively used in many communication systems.
Trunking systems allocate a few frequencies to many
different users. When the mobile unit transmits a
signal, one frequency is chosen from among the
allocated frequencies in that trunking system. The
user’s ID talk group is sent with the signal.
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 fi nds 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