Simple question about Talk Groups

[Skadar]

I can't seem to find an answer to this newbie question about Talk Groups.

Is the programming of Talk Group IDs into a scanner required to get trunking to work? Or are they merely for your convenience in being able to see what service is currently speaking?

[DickH]

Originally Posted by Skadar

I can't seem to find an answer to this newbie question about Talk Groups.
Is the programming of Talk Group IDs into a scanner required to get trunking to work? Or are they merely for your convenience in being able to see what service is currently speaking?

Once you understand trunking you will understand Talk Groups. Here is a simple explanation.

How a Motorola trunking system works
OVERVIEW:
The object of trunking is to allow many users to share a relatively few frequencies.
A trunking system is controlled by a computer. Information (data) is exchanged between the radios and the computer on a control channel, sometimes called a data channel. It sounds like a strong buzz.
A large system can have up to 28 freqs., 4 of which may be used as control channels. The control channel may be changed once a day or as often as the programmer decides. Some scanners need only the control channels to track the entire system. In that case just enter only the control channels.

After the frequencies are entered, the banks become scan lists or sub-banks that hold the Talk Groups or IDs.

Each group of users (Fire, Police, etc.) is assigned TALK GROUPS. In a Motorola Type II system, the most common type, TGs are usually in 32 number steps starting with 16 and going up to 65536; 16, 48, 80 --- 4656, 4688, 4720 --- 28944, 28976, etc. System radios can have more than 100 TGs programmed into them.

When a user pushes the talk button on his radio, data is sent to the computer. The computer chooses an unused freq. and sends that data to all the radios using the TG of the originating unit. This all happens in a fraction of a second and it happens EVERY time a radio is used.

EXAMPLE:
Fire Dispatch calling Engine 4 (TG 4528 on 856.7125)
Engine 4 answering Dispatch (TG 4528 on 867.2625)
Respond to 73 Elm Street (TG 4528 on 855.9625)
Engine 4 responding (TG 4528 on 858.4375)

If you have entered TG 4528 into your scanner, it will decode the control channel data and change your scanner freqs. to follow the conversation on TG 4528.

Some scanners have 2 modes, OPEN and CLOSED or SEARCH and SCAN.
OPEN or SEARCH receives all TGs using the system.
CLOSED or SCAN receives only the TGs YOU have put into the scan lists.

This should get you started, but you should read the manual carefully. You may need to read it several times.

[Don_Burke]

Originally Posted by Skadar

I can't seem to find an answer to this newbie question about Talk Groups.

Is the programming of Talk Group IDs into a scanner required to get trunking to work? Or are they merely for your convenience in being able to see what service is currently speaking?

I can run mine in the open mode and hear all of the talkgroups without entering any.

If I want to exclude the garbage trucks and convention center housekeeping, entering talkgroups can make that possible.

[Skadar]

Originally Posted by DickH

Some scanners have 2 modes, OPEN and CLOSED or SEARCH and SCAN.
OPEN or SEARCH receives all TGs using the system.
CLOSED or SCAN receives only the TGs YOU have put into the scan lists.

Boom! This looks like the information I was missing. I programmed the 6 frequencies of my local trunk system (EDACS) in order but chose NOT to enter any Talk Group IDs at this time. I recall that Win97 defaulted the bank as CLOSED. This appears to be the reason why my scanner appears to be picking up signals from the trunk, but I am unable to actually hear anything.

I'll try setting the mode as OPEN to see if I can hear anything. Otherwise, I'll go ahead and enter the Talk Group IDs and see how that works.

And thanks for the concise explanation of trunking. Much of the info out there is a bit overwhelming for a newbie.