FBI P-25 Digital

[tazz]

Can anybody confirm if the FBI has some sort of radio talk group ID numbers on their P-25 Digital frequencies ???

Was getting some non encrypted radio traffic on 167.7625 MHz, and it had a radio talk group ID #1

Unit ID number was 3204348, and the frequency had a NAC Code of 167

Transmissions appeared to be some sort of aircraft doing some aerial surveillance on some people. Not sure where they were flying because none of the streets sounded familiar. There was other radio traffic on the frequency but it was encrypted.

My monitoring location was in SE Ohio, and monitored the radio traffic on a ICOM IC-R30.

 

[nd5y]

All conventional P25 (repeaters and simplex) has talkgroups. Not just trunked systems. The default talkgroup is 1.

 

[tazz]

OK, thanks for the info. That's what I was thinking, but wasn't too sure.

 

[ecps92]

YMMV as most portable/mobiles/base stations may be programmed as TG 1, but I've seen consoles using 4095
Depends on who programmed the system.

RID's of 320xxxx are for the Indianapolis Field Office

OK, thanks for the info. That's what I was thinking, but wasn't too sure.

 

[scannerboy02]

As was mentioned above, ALL P25 radios have a talk group ID of some kind. The default TGID is 1 but they can program any TGID (or several TGIDs) they want as long as all the radios are using the same TGID to communicate with each other. You will also see the 65535 "all call" TGID being used by the base station/dispatch from time to time, they use this TGID so all radios of the frequency will hear the traffic from the dispatcher no matter what TGID is in the radio.

 

[reconrider8]

So when the radios are in vote mode does that tx on the tgid also or only when someone keys up?

 

[BigLebowski]

Vote Scan beaconing is more a function of the system.

So when the radios are in vote mode does that tx on the tgid also or only when someone keys up?

Also be aware that depending on which brand of radios an agency is using, you may see talkgroups pop up other than the default "1" and they in most cases are for programming reasons/limitations and are transparent to the end user. Most Motorola subscribers transmit a default talkgroup of "1" and are in fact not even programmed to do so by the radio techs, it is just a default. When programming Harris radios, if you want to mix encryption keys or algorithms in a P25 conventional system, it is accomplished with talkgroups (general practice is to use 6xxxx). This is transparent to the end user unless selective squelch is used on both sides.

 

[wsmoore]

Somebody on the Boards said the 4095 Id is the Motorola Default Id for the DIU.

YMMV as most portable/mobiles/base stations may be programmed as TG 1, but I've seen consoles using 4095
Depends on who programmed the system.

RID's of 320xxxx are for the Indianapolis Field Office

 

[RaleighGuy]

TG 4095 and 1 are commonly used by USSS also for VP/POTUS protection details.