A talkgroup (TG) on the PRN system is like a channel on an analog radio. If you have your radio on one talkgroup, you will not hear a user on another talkgroup, even if they are on the same repeater.

Digital Mobile Radio repeaters have 2 time slots (TS) available and, on the PRN system, the entire network is linked full time on time slot 2, Talkgroup ID 2. This talkgroup is available on every repeater on the system. The only time this talkgroup may not be linked up is if a repeater is needed for a special event, such as a parade or race. Once the event is over, the repeater will be linked back to the network.

Some of the other talkgroups that you will need to know about are listed below, along with an explanation of what they do.

Monitor All Channel

This channel is a receive-only channel that lets you monitor Time Slot 1 for any talkgoup activity before you use it. Ideally, you should monitor this channel for a few moments before using one of the On-Demand talkgroups to make sure that Time Slot 1 is not already in use.  If you hear activity on time slot 1, it means someone is using the TS, or a net is in progress. PLEASE DO NOT clear the time slot if you did not activate the link.

Local Talkgroups

Each repeater also has a local talkgroup that is utilized for local communications. These talkgroups are always on, not linked, and do not go out over the network, so you will not be tying up all of the repeaters if you use these.

Clear Timeslot Talkgroup

This TG clears all of the On-Demand links on the repeater you are using. This may be used as a courtesy once you are done using one of the On-Demand talkgroups.

How The On-Demand System Works

Time slot 1 utilizes several on-demand talkgroups, depending on which repeater you are on. On demand means that by default the link is not active. If you want to make it active, you change your radio to that talkgroup and key up until you get the talk permit tone and then release your PTT. This will activate the link.  It is important to understand that if anyone is currently chatting on that talkgroup you only will begin to hear audio once the next person starts to speak. This is why you do not want to immediately throw out your call. If the talkgroup is currently active, once the user who was talking when you activated the link stops speaking, the c-Bridge will begin to pipe the audio in to your repeater. If there is no local activity on the talkgroup within 5 minutes, the link timer will expire and the talkgroup will go quiet again.

Consider using the “Clear Timeslot” option once you have finished your conversation to clear the link before the timer expires. By keying up on the “Clear Timeslot” talkgroup you are clearing all of the On-Demand links on the repeater you are using immediately instead of waiting on the timer to expire.

Repeater to Repeater Talkgroups

There also are two Point-to-Point or Point-to-Multipoint talkgroups named PRN Chat 1 and PRN Chat 2 that may be used instead of tying up the PRN talkgroup.  These talkgroups are On-Demand on every repeater, and will unlink after 5 minutes of inactivity on the repeater.  You may also clear them immediately by using the Clear Time Slot talkgroup.

Echotest

The Echotest talkgroup can be used to hear how well you are being heard by the repeater you are connecting to.  Key up on this talkgroup, say your call, and your audio will be recorded and replayed back to you by the Echotest server.

NEVER, UNDER ANY CIRCUMSTANCE, USE THE ECHOTEST TALKGROUP FOR CONVERSATIONS! 

Thanks to Cort Buffington (N0MJS) and the K0USY Group for their hard work on this software and allowing radio amateurs to use it for free.  “DMRlink” by [K0USY Group] http://k0usy.strikingly.com and is licensed under CC BY-SA 3.0.