[TrunkCom] How do I program trunked radio systems?

[Steve Matzura]

Hi, Trevor:

On Mon, 30 Oct 2006 17:52:04 -0700, you wrote:

>I am wondering how to program trunked radio systems....... How do you program the control channel and the talk group ids? 

I can't give you specific info for your scanner because I don't own
that model, but I can give you a short primer on how trunked radio
operates and how you program around its intricacies and differences.

There are now two types of radio systems--conventional (the ones
you're already used to where one repeater has many users and you
usually listen on the repeater's output side), and trunked (where many
repeaters are shared by many more users and each conversation is
assigned to one repeater frequency pair via the computer that controls
the system). Trunked systems make use of an additional frequency pair,
called a control channel.

Trunked radio system users are divided into groups that have different
names, depending on the trunking system type being used.  Some are
referred to as agencies, some as fleet maps.  Each individual radio is
assigned either an agency and talkgroup ID or a fleet map number,
which is more or less the same thing. When the radio operator keys his
radio, that information in sent to the controlling computer, which
then assigns that radio a repeater (frequency pair for transmitting
and receiving) to use. Now, anyone in the talkgroup or fleet map will
hear the conversation and can instantly join in without having to ask
the control computer to assign them a private channel.

On the other hand, if you wished to speak to another individual on the
trunked system but not have the entire talkgroup or fleet hear your
transmission, you use what is called an individual call or I-Call.
Not every trunked system has this capability, and some that do have it
disabled.  Some scanners can follow I-Calls, some cannot, which makes
doing it manually a real challenge sometimes.

There are at least two major types of trunked radio systems--Motorola
and EDACS. Motorola systems are subdivided into types I and II.  There
are even hybrids of type I and II in the same system.  There's also a
third major type, called LRS. It's imperative that you know the system
type for the system you are attempting to program, otherwise you won't
be listening in the right places for the right things, or you may be
monitoring frequencies you don't need to monitor.  For instance, for
one type of trunking system, all you need is the control channel
frequency and the frequency steps to calculate the frequencies of all
the other channels.  In this system type, the control channel
frequency never changes.  In others, you'll need to know the
frequencies of all the output channels in the system and program them
separately but as one system because the control channel can be
assigned to any available channel among the list of frequencies for
that particular radio system.

Another pair of terms you will need to know is "ID search" and "ID
scan". Your radio may call them something else, but the concept is
this:  In ID scan mode, your radio will lock onto and enable you to
listen to only those talkgroups or fleet maps you have programmed into
it.  ID search, on the other hand, lets you hear everything, which,
for a new trunking system listener, is what you want to do.  You want
to hear everything, then note down which talkgroups are of interest
(or uninterest) and program those specific ID's into your radio to
either enable monitoring or lock them out if you don't want to hear
them.

I hope this helps you get started.