Uniden Bearcat BCD396T, Owner'S Manual

Page: 25 / 154

25
Understanding Scanning
each group operates on...and this frequency selection
is made each time a user transmits. So, while on a
conventional system queries, replies, and follow-ups
are all on a single frequency, they could each be on
completely different frequencies on a trunked system.
This semi-random frequency assignment made
monitoring such a system impossible prior to Uniden’s
invention of the TrunkTracker scanner.
Not only does your BCD396T scan channels like a
conventional scanner, it actually follows the users of a
trunked radio system. Once you know a talk group’s
ID, you won’t miss any of the action.
If you are a new scanner enthusiast, you might want to
read the first part of this manual and use your scanner
in conventional mode before you begin trunk tracking.
Understanding scanning fundamentals and
terminology will make trunk tracking much easier. If
you are already an experienced scanner operator, you
might want to go to “Programming Motorola Systems”
on Page 63, “Programming EDACS Systems” on
Page 67, or “Programming LTR Systems” on Page 70
now.
Types of Trunking Systems
Trunking systems divide a few frequencies among
many different users, but the way that each system
does this is slightly different. This section describes
some of the technical data behind Motorola, EDACS,
and LTR trunked radio systems.
Motorola Trunking
While there are different types of Motorola trunking
systems, they all use the same basic trunking method.
The system consists of one control channel (or as
many as 4 per system but only one is active at any
one time), plus one or more voice channels (typically
10, 20, or 28 total channels). When a user presses
Push To Talk (PTT) to transmit, their radio first sends
their talk group information to the control channel.