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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-97 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 channel memory location number on the
third line and the Motorola ID number on the bottom line.