Picking up occasional traffic from a different TRS?

[furrowing owl]

I've been running SDRTrunk v0.5.0-alpha 6 for the last couple of weeks primarily set on one county's P25 system, with a wildcard alias specifically set to log and record any talkgroups that aren't otherwise documented. So far, it's worked pretty well. The problem is that I'm apparently catching occasional traffic from a neighboring county's P25 system as well. I suspect that the program might be misreading the control channel, and jumping to that other system, but honestly that's just a wild guess on my part. There are no duplicated frequencies between the two systems, but they do overlap each other on the spectrum.  No ISSI linked talkgroups either. I deleted the information for the second TRS entirely to be doubly sure that the program wasn't simply scanning both systems at once, but it's still going on.

Anyone have a clue what might be going on here?  I suppose I can always lock out the offending talkgroups once I've identified them, but is there a way to prevent this from happening in the first place? Also, is there a way to log the frequency that given traffic came in on? That'd at least allow me to figure out if I'm looking at one of these "lost" talkgroups without having to wait for someone to mention an address.

[Neil Harvey]

Doesn’t P25 allow for linking/bridging of systems?  So they ARE separate systems, but can be linked when needed?  E.g. a highway patrol unit needs to communicate with local city units?

 

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[furrowing owl]

I presume they could be, but the general consensus of the old hands around here is that they're not currently linked.      

Dekalb County, GA is the one I've been trying to listen to: https://www.radioreference.com/apps/db/?sid=5638

Fulton County is the interloper: https://www.radioreference.com/apps/db/?sid=8340

[GTR8000]

Post some screenshots of your Channel configuration, as well as the Now Playing and Tuner screens so we can see what your setup looks like.

[furrowing owl]

Note: The "North Fulton Regional" system that appears in the Channels screenshot is not the same one that I've been having problems with.  Same county, different TRS.

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[GTR8000]

I don't see anything unusual in your configuration, so this is a bit of a mystery. For the channel definition, enable Call Events logging. That will keep a running log of all talkgroups and frequencies that SDRTrunk has tuned to, that might provide a clue.

[Baby Baby]

I listen to my county's P25 trunk which is part of the magnificent KCICS system.  I have noticed that other counties' traffic

will appear if...

1) We are close friends.

2) A radio user wanders into our county the radio is programmed to use our trunk.

3) There is an emergency and our neighbors want us to be able to communicate with them seamlessly.

1) I hear EVERYTHING from the county to the west.  It is simply repeated into my county's trunk.

2) If a far-away LEO drives into my county for a "pickup or delivery" I will probably hear traffic from his/her county.

3) This seems to be event driven.  Once there was a false-alarm fire at a university kitchen in a county for a talkgroup I

normally never hear.  It popped up and then vanished once the "disregard" was given.

Interesting stuff.

[furrowing owl]

Curiouser and curiouser...  I ran it with Call Events logging switched on for my home system for 20ish hours.  All of the recordings from both systems are showing up with file names pointing towards the system I'm trying to listen to, which has always been the case.  The Call Events log shows only the entries for the traffic in my home system.  

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[WillHam]

I have this exact issue. I monitor Fulton County P25 system with a stand-alone well qualified system. I use 2 Nooelec v4 SDRs and am thinking about upgrading to fancy SDRs to see if that helps. I monitor TG 61001 mostly but randomly with hear 51001,51101 and some others cut in. I also noticed that emergency tones seem to scramble things up a bit. When I do hear rouge traffic from other TGs it's also accompanied by distortion or a beep. 

[WillHam]

Also I should include that this is with SDRtrunk 5.0 alpha 6 and JMBE 1.07b.

[furrowing owl]

Ultimately, I ended up just creating an entry for those in the playlist, and setting it to mute those channels.  On my end, maybe two-thirds of these transmissions are at least somewhat garbled, but there are some that are perfectly good.  It's definitely an intermittent thing, as I'm constantly picking up a line here and a line there, and not whole conversations.  It seems like I'm getting traffic from Fulton while I'm monitoring Dekalb, but I haven't observed traffic from any of the other local systems.  (...and for those not familiar with the area, there are a lot of P25 systems to choose from.)  

The program does occasionally record transmissions from talkgroups within the system that I'm monitoring that are not set to record as well.  It's a bit less common, but it does happen.  

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