172.2125 P25 - What is this?

[Gilligan]

I've been picking up P25 traffic on 172.2125 for quite a while now and I'm starting to wonder if it is an interoperability repeater. It was quiet all morning until about 11:57 am. Then I got a minute of traffic. Then silence for about 2 minutes, then more traffic. It seems very coincidental for there to be no traffic until almost exactly noon. The problem is that I can't hear P25 -- no digital scanner here. I'm also hearing quite a bit of activity now since 4:15 (to about 4:30 pm).

Maybe you guys can give this freq a listen because it may be more important than we think. This is one of the frequencies for an interop repeater in Chicago, according to MT Fed Files. And it has a fairly strong signal, as I can get it easily with a stock antenna on my Pro-97.

Now for the last ten minutes this freq has gone nuts! Almost constant activity. 5:30 pm

 

[ChrisP]

172.2125 MHz is a newer Justice Department allocation that is indeed being used as a federal interop repeater in the Chicago area. It's also being used as part of the JIWN VHF P-25 trunked system up in the Pacific Northwest.

All of these federal interop channels are coming from the Justice Department frequency pool. The frequency may be used for other Justice Department operations as well, so without hearing what the traffic is, it will be hard to figure out if this is an I/O repeater, or something else.

- Chris

 

[Gilligan]

It is certainly buzzing quite a bit this evening, even now as I type.

 

[K5JAB]

I'll be in town tomorrow around 1130-1200. I'll listen in with the PRO-96.....

 

[Gilligan]

I appreciate it. I am really wondering just what kind of traffic is on this frequency.

 

[dstew67]

I'm listening to it now. Everything I'm hearing is encrypted.

 

[K5JAB]

Yup.... That's what I was afraid of.

 

[Gilligan]

Thanks so much for checking into this. Now I have a very good idea that it is indeed an important frequency.

 

[mam1081]

It's active again today.

DES-OFB encryption.
NAC = 370

I'm only seeing 2 or 3 different radios keying up.

 

[Gilligan]

It's active again today.

DES-OFB encryption.
NAC = 370

I'm only seeing 2 or 3 different radios keying up.

That would probably eliminate interoperability, then. Could be FBI -- they use that range.

 

[mam1081]

That would probably eliminate interoperability, then. Could be FBI -- they use that range.

I wouldn't say that - encryption keys could be "standardized" across several [federal] agencies.


Has anyone heard anything "in the clear" on that channel?