Bartlett Public Safety

[Airdorn]

Hi there friends!

Tonight, I heard a lot of what sounded like Fire department chatter on talkgroup 65112, which is not in the database.

I use DSD+, and when I tune Bartlett PS I get something like:

Patch Supergroup: TG=65112
Patch Subgroup: TG=8001

Patch Supergroup: TG=65112
Patch Subgroup: TG=301 [Fire - Chan A Dispatch]

Patch Supergroup: TG=65112
Patch Subgroup: TG=308


I have TG 301 as Bartlett Fire Dispatch, but no 8001 or 308. Are those also some kind of Fire talkgroup that needs to be added to the RR database?

What is TG 65112? I wonder why there was so much activity on it tonight? It all seemed pretty run-of-the-mill stuff.. old lady with a bleeding leg, fire alarm at some residential home, etc.

I thought the 65xxx TG's were all for interop stuff.

Oh, and also, the Radio ID of the dispatcher (5010104) was different (but VERY close!) to the Radio ID of usual Police dispatch (5010103). And anytime someone called dispatch on TG 65112 DSD+ showed it as a "P-Group call". Dispatch answered as just "Group call".

Just trying to fully understand what's happening here, thanks for any insight!

 

[doctordialtone]

65112, which is not in the database.

You are likely seeing ISSI, which are temporary talk groups, which show up as 65XXX.

This explains ISSI

https://www.motorolasolutions.com/c...25/project_25_issi_solution_brief_global_.pdf

Chances are they will change by tomorrow.

 

[jblackst]

It's like an ad-hoc talk group id.

 

[Airdorn]

Yes, but why? It's just the local Bartlett fire dept. doing their business in the City of Bartlett.

 

[jblackst]

A for instance: dispatch selects multiple talk groups in a simul-select for a transmission. The system might, in this instance, use an ad-hoc talk group to process and transmit the call one time on the ad-hoc talk group as a matter of resource conservation, instead of sending the message over several different talk groups on multiple transmitters. It's nothing nefarious, it's just one way the system might conserve resources.

There are other reasons why the system might do this, but I'll still claim that there is nothing sneaky going on.

In your example above, TG 301, 308, and 8001 are 'patched' together, and the system created this temporary talk group 65112 to actually handle the traffic. The system tells the radios where to expect the traffic on the fly. Science 😉

 

[jblackst]

Also, 8001 is Roane County Net. The RRDB doesn't have an entry for 301 or 308, yet, on TACN.

My bad, Bartlett is in Shelby County and they're not on TACN, are they.

 

[Airdorn]

Also, 8001 is Roane County Net. The RRDB doesn't have an entry for 301 or 308, yet, on TACN.

My bad, Bartlett is in Shelby County and they're not on TACN, are they.

No, Bartlett has their own system.

But thanks for the info... it makes more sense now.

 

[INDY72]

Bartlett can be patched to the TACN. It can also be patched with the Memphis/Shelby P25. Any of the area systems can be patched outright, or they can set up an ISSI link. These are usually just temporary, but some can be almost permanent, or even full time permanently based (like the Bartlett/Memphis TG). Here on our local system, the Fire/Rescue has 2 TG's that are almost permanently patched together. Also every night, on the Police side, they patch at least 3 of their TG's together. The combined patched groups form an "Supergroup" where everyone on each of the individual "Subgroups" can hear and talk to each other as if they were all on the same TG. They also do patches to the State system when needed. Interoperability for the win! (Most scanners can not see the "Supergroup", but programs like Pro96Com, and Unitrunker, and DSD can. I am not sure if the Unications have the multigroup ability for patches or just hear them on one of the patched TG's/Freqs. I will have to look in my PPS to see.) *EDIT: It looks like yes, you can do supergroups in the Unications. * Also patches are common in some DMR systems, especially on the ham systems where they combine TG's all the time for networking. (Not so much in Brandmiester, but the other nets do, especially DMR MARC)