Radio Shack PRO-95 Owner's Manual page 22

Motorola systems are trunking
systems used primarily by
business and public safety groups
to efficiently allocate a small
number of frequencies (as few as
five) to many groups of users (as
many as several thousand). To do
this, each group of users in the
system is assigned to a specific
talk group. For example, the east
side patrol officers might all be
assigned to talk group 2160. One
channel in the system is
continuously transmitting data that
identifies which talk groups are
active on which channel. In
addition, this talk group
information is also transmitted as
subaudible data on each active
channel.
When the scanner receives a
transmission on a channel set to
the Motorola mode, it first decodes
the talk group ID data included
with the transmission. In the open
mode, the scanner stops on the
transmission and displays the talk
group ID on the bottom line of the
display. In the closed mode, the
scanner only stops on the
transmission if the talk group ID
matches a talk group ID that you
have stored in the bank's talk
group ID list and have not locked
out.
Motorola trunking systems come
in three categories: Type I, Type II,
and Type I/II Hybrid. Each
category displays and uses talk
group IDs in slightly different
ways.
Motorola Type I IDs are in the form
FFF-SS , where:
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