CG on 412.8625

[Wilrobnson]

These are all on the same freq, same NAC. I've not yet heard them used simultaneously.

As an aside, I've only heard different TGIDs being used with the same NAC on the same freq one other time, a Seattle-area Emergency Management agency programmed NIFOG information with their own talkgroup number (as opposed to default 1) and was stumped that no one was hearing them during an exercise.

They later changed the NACs and thought the problem was 'fixed'.

 

[trentbob]

These are all on the same freq, same NAC. I've not yet heard them used simultaneously.

As an aside, I've only heard different TGIDs being used with the same NAC on the same freq one other time, a Seattle-area Emergency Management agency programmed NIFOG information with their own talkgroup number (as opposed to default 1) and was stumped that no one was hearing them during an exercise.

They later changed the NACs and thought the problem was 'fixed'.

Interesting, I get the part about one conventional p25 frequency having a different NAC applied to each group so only that group can hear each other and the others on the conventional p25 frequency cannot. That was obvious.

What's Curious is how you describe talk group IDs yet everyone's on the same NAC on the same conventional frequency.. what generates a talk group ID if it's not a system but a single conventional p25 frequency all using the same NAC?

Could it be a system with IDs combined with a p25 conventional frequency.

That's something I'd like to know more about, talk group IDs on a p25 conventional frequency with only one NAC.

I'd like to know if it's being used in the New York Long Island and Philly area, if so, I want to monitor it. Maybe it's done with other agencies.

 

[ChrisP]

What's Curious is how you describe talk group IDs yet everyone's on the same NAC on the same conventional frequency.. what generates a talk group ID if it's not a system but a single conventional p25 frequency all using the same NAC?

Trentbob, on a conventional system, it's just another way of separating users on a common channel. You can have a single frequency, with a single NAC for all users, but assign different talk groups to different users on the frequency. If your frequency is not busy, it allows multiple users that won't hear each other. But you can set up an Announcement Talk Group (on P-25 that's TG 4095) that goes to all users on the frequency regardless of what talk group their radios are set to.

I have seen some talk groups other than 1 and the Announcement talk group used on some US Secret Service, the FBI and Federal Protective Service conventional channels.

There is a single frequency used by the VA medical center near me that does that. They have a single DMR frequency and about 10 or 12 different talk groups on that frequencies for different users. It's not trunked, and it's not that busy, so anyone getting bonked with a busy signal is pretty rare.