Talk Groups
Pacific Northwest 220Mhz Repeater Network
 and Friends
Talk Groups
Whats this “talk group 42” that I keep hearing? And what’s with the little burble sound 60 seconds later?  )
The PNW220 repeater system now has analog talk groups. While similar to DMR they are NOT DMR nor are they connected to DMR in any way though both use a similar talk group structure.
Analog talk groups are simply a means by which you, on demand, can link the repeater you’re on with one or more other machines in the PNW220 system. While linked in this way all conversations on machines linked to a common talk group share audio connections while all others not on that talk group hear nothing or can be used for other conversations.
The beauty of this approach is you can avoid bringing up every system in the network when all you want to do is contact someone on another part of the network. Ex. N7IPB is on Baldi and wants to talk to WA7FUS on Lyman. The old way ties up all the repeaters (eight at last count) with one conversation. While this is normally good, some of the time it can be a waste of resources. With talk groups you can use only the resources you need. All of the other repeaters are still available and will not even be aware that the machine you are on and the one you’ve selected are in use.
Other combinations can also be available such as groups of machines. Currently we have not defined any groups.
And the ‘burble’? That’s the sound when the talk group reverts to standby waiting for another talk group selection. Currently 60 seconds after the last repeater use.
How does this work?
  • Manual talk group selection
To manuall select a talk group use a DTMF command to select a desired talk group. The generic form of this command is “91<talk group number>#” Talk group numbers for each of the repeaters are in the list below.
    • 42     = ALL repeaters
    • 4200 = Lyman
    • 4210 = Gold
    • 4220 = Capitol
    • 4230 = Baldi
    • 4240 = Bawfaw
    • 4250 = Rattlesnake
    • 4260 = Blyn
    • The Hawaii link is currently on the same talk group as Capitol
To use this method bring up your local repeater, announce that your bringing up a destination and then issue a command. Example. For someone on Baldi, key up the repeater as you normally would and say something like “N7IPB dropping off all but Lyman” and then send the command “914200#”. Then unkey, wait for the announcement and then call the other party as you normally would. If they answer within 60 seconds just carry on your conversation as long as necessary. When you finish the system will revert to normal after 60 seconds. If your party doesn’t answer and the timeout occurs you will have to re-issue “914200#”.
  • Select by CTCSS tone
  • Select by CTCSS tone is currently only enabled for LOCAL and ALL.
This method makes use of another new feature., the ability to select a talk group (TG) by CTCSS tone.
All the repeaters have been programmed to recognize a common set of CTCSS tones and depending on which one you’re using, automatically select a talk group. The list below shows the CTCSS and target repeater mapping. Simply program two memory channels with the repeater frequency and a CTCSS of 100hz and one with 103.5hz. You can then use one memory channel for local and the other for system wide.
    • 100.0 = Local - Local Repeater only
    • 103.5 = ALL – The whole linked system
    • 110.9 = Capitol Peak uses 110.9 for All
  • Additional Commands
More commands to support talk groups are available but the above will get you started. The additonal commands are listed here
    • 9*# -- Talk group status
    • 91# -- Select previous talk group
    • 91<TG># -- Select talk group TG#
    • 92# -- QSY all active nodes to a talk group assigned by the reflector server
    • 92<TG># -- QSY all active nodes to TG#
    • 93# -- Follow last QSY
    • 94<TG># -- Temporarily monitor TG#
Note the difference between selecting a talk group and performing a QSY. The select commands only change the talk group on the local node. The QSY commands change the talk group for all nodes currently connected to the talk group where the QSY command was issued. However, a QSY request is only honoured for active nodes, that is nodes that have been a talker on the current TG. The "follow last QSY" command can be used on non-active nodes to force it to follow the QSY. The QSY feature is typically used after first calling on a "broad" talk group. When all participants have joined by answering the call, the QSY command is issued and all active nodes switch to the QSY target talkgroup while the passive nodes stay on the currently selected talk group.
Copyright © 2020-2021 by Ken Koster - N7IPB
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