Unitrunker Help

[jsokolowski]

I am trying to listen to Site 2 at the following link: Overlay Regional InterOperability Network (ORION) Trunking System, Various, Virginia - Scanner Frequencies. I am using Airspy as the input to Unitrunker and DSD+ for the digital voice decode. It appears Unitrunker is decoding the P25 signal properly but I have no audio doing to DSD+ and no voice channel switching taking place as far as I can tell. There is a strong audio signal indicated for virtual audio cable. Here is a screenshot of my setup. Any thoughts as to the problem?

 

[rivardj]

You need to select APCO P25 in both the Signal and Voice sections on the VCO tab for each receiver. See the link below for an example.

http://forums.radioreference.com/2626506-post12.html

Other settings in the examples may not work with your configuration as you are using an Airspy and my setup SDR-RTL.com dongles.

 

[jsokolowski]

Ok thank you. I will give this configuration a try.

 

[dave3825]

How many voice receivers are you using? I see 5 vco's in there. Tick the Apco p25 boxes to on. You might need to set the center freq in the voice vco. What is the sample rate set for in the voice vco?

Looking at the freqs for site 2, are they all used? Almost look like repeater pairs.
Site 1 and site 2 are listed (here on rr) as both being in the same spot. Can you by chance receive site 1?

 

[jsokolowski]

I am using three vco's. One for signal and two for voice. Sample rate is 10. All the control channels for Site 2 are used on an alternating basis. I think all the voice channels are also used but have not been able to confirm. I have not tried Site 1 but will. Thanks for the advice.

 

[jsokolowski]

Unfortunately none of the above helped. I looked at Site 1 but it was not active. Will keep searching for a solution.

 

[SCPD]

What do you see in the "Svc" column when a call is active?

 

[AggieCon]

In your screenshot, it UT is calling the system you are monitoring a Motorola system, not P25. Also, if monitoring the second site, one dongle is not going to cover all of the voice channels.

I think you are on some other system.

Indeed, I think this is it: Virginia Beach Trunking System, Virginia Beach, Virginia - Scanner Frequencies

The talk groups look more like that system too.

Confirm your frequency drift correction. Those control channels are 20,000 hertz apart.

Edit: NVM. Forgot you had an Airspy, you should be able to cover. I am vague on how stable that receiver is. Can it be off that far? At any rate, disable discover and disable Motorola on the signal VCO so it'll look for the control channel of the P25 system. Turn of UT's frequency drift correction on the info tab.

 

[jsokolowski]

I will check on the Svc column to see what it indicates. I will also make the other changes indicated above. I believe you are correct in that I am copying the VB system vice the ORION system. I don't see any active trunking signals directly on or near the ORION control frequencies.

 

[AggieCon]

Check all of the system frequencies, not just what is listed in the RR DB as a control channel. Check the FCC licenses too if need be.

 

[jsokolowski]

I finally got the system to work at least with analog audio. The group I was monitoring turned out to be a different one than noted above. I still haven't found the system control channel that I was originally looking for. Will keep searching. I am not sure about the 20,000 hertz difference on Airspy. In the lower frequencies like the aircraft band it is right on.

 

[AggieCon]

If you have "drift correct" enabled in UniTrunker (on the info tab), it uses the squelch value to find and adjust to a frequency. If there was a control channel on a nearby frequency, the software can become confused and lock onto the wrong frequency. In this case, you found a different system.

Use SDR# and I bet you will find the control channel for the P25 system.