What Is Trunk Tracking; Trunked Scanning; Types Of Trunking Systems - Uniden Trunk Tracker IV BCD996T User Manual

What is Trunk Tracking?

Your BCD996T is designed to track the following types of trunking systems.
•
Motorola Astro 25 (APCO 25) trunking systems.
•
Motorola Type I, Type II, Type IIi hybrid, SMARTNET, and PRIVACYPLUS analog trunking systems, which are extensively
used in 800 MHz communication systems.
•
LTR trunking systems
•
EDACS SCAT trunking systems
•
EDACS trunking systems
When tracking these types of systems, you might want to remember that your scanner can track more than one trunking system at a
time and scan conventional and trunked systems at the same time.
Conventional scanning is a simple concept. You enter a frequency used by someone you want to monitor into your scanner's
memory. For example, the police in your area might transmit on 460.500 MHz, the fire department on 154.445 MHz, the highway
department on 37.900 MHz, etc. So when your scanner stops on a frequency, you usually know who it is, and more importantly, you
can stop on a channel and listen to an entire conversation. This type of scanning is easy and fun.
However, as the demand for public communications has increased, many public radio users do not have enough frequencies to meet
their needs, creating a serious problem. Trunking radio systems help solve this problem.

Trunked Scanning

While conventional scanning worked great while there were only a few groups wanting to use the frequencies, with the advent of
smaller, lower-cost radios more and more agencies and businesses wanted to take advantage of the utility of 2-way radio. As a
result, the bands that were used most became full, so new users were not able to take advantage of the technology as quickly as
they wanted.
Trunking solved this frequency shortage by allowing multiple groups to use the same set of frequencies in a very efficient way. While
each type of trunking system operates a little differently (see the next few sections), they all work on the same basic premise: even in
a system with a lot of users, only a few users are ever transmitting at any one time.
Instead of being assigned a frequency, as with conventional systems, each group is assigned a talk group ID. A central computer
controls the frequency 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 BCD996T scan channels like a conventional scanner, it actually follows the users of a trunked radio system.
Once you know and program a talk group's ID (TGID), 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 can review the programming worksheets and their associated pages in the
Reference Section of this manual.

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 the person's talk group
information to the control channel. The computer then assigns that talk group to a specific voice channel and transmits that data over
the control channel. All radios in that talk group switch over to the assigned voice channel and the user can begin speaking. This all
10