Can someone explain whats going on? SDR P25 phase 1

[rumfordsa]

So after a week of trial and error I've finally managed to get my SDR dongles to pick up and decode Apco 25 phase 1. So here's the issue I have now. I've plugged in the control frequency for the county I wanted to monitor off of radio reference's database and everything works a little to well. I'm new to this whole digital radio system but is it normal to pick up agencies off frequency. To explain a little better the frequencies I'm mongering are for Ford county Kansas. I'm picking up radio traffic for Clark, Hodgeman, Gray, and Finney counties as well. None of which share control channels or any other channels/frequencies for that matter. Can someone explain whats going on?


EDIT: Here is the link to the frequencies referenced above:
http://www.radioreference.com/apps/db/?sid=4390

 

[wtp]

probably it is just that they are affiliating with your local tower and you can hear them.

 

[rumfordsa]

probably it is just that they are affiliating with your local tower and you can hear them.

But in order for them to be affiliated wouldn't they share the same frequencies or control channel? These are radioing to a different communications department all together.

 

[boatbod]

Trunked radio systems can share many different talkgroups on their network of sites. The link you provided lists all the agencies and associated tgid values. If you want to only receive specific agencies communication, you need to configure your software to only play those specific tgids

 

[rumfordsa]

Trunked radio systems can share many different talkgroups on their network of sites. The link you provided lists all the agencies and associated tgid values. If you want to only receive specific agencies communication, you need to configure your software to only play those specific tgids

So how would I go about limiting the talk group ids

 

[boatbod]

So how would I go about limiting the talk group ids

That really depends on which software you are running. I can tell you how to do it with op25 but I'm not familiar with any of the others.

 

[rumfordsa]

Yea, I'm running DSD+ and Unitrunker. What are you running OP25 on?

 

[boatbod]

What are you running OP25 on?

Lots of different hardware... three different laptops running Linux Mint, one Intel NUC7 and (occasionally) a RPi3B. I primarily monitor the Maryland FiRST P25 Ph1/Ph2 system.

 

[jbeen]

There are two approaches to limiting monitored Talkgroups in Unitrunker...

You can either lockout all the TGs you don't want to hear, but that ends up being a bit whack-a-mole, as new TGs show up.

Another way is to use the Rank feature.
Give any TGs you want to monitor a Rank less than the default 50 (like 40).
Then, set the Rank on your voice VCO/VFO(s) to the same number.

Josh

 

[dave3825]

If you using Unitrunker, just lock out every talkgroup you are not interested in. Open systems tab, then select the system, then select groups.

If your using dongles and DSD, open your groups file in DSD and find the tg's you do not want to hear and replace Normal with L/O. Like this,

Con+,      171,       301600,   50,  Normal,      72,  2016/06/25  9:28,  "LGA"
Con+,      171,       301601,   50,     L/O,    3171,  2018/11/20 15:55,  "LGA Parking"