sdrtrunk - Control Channel / Problems

[emptyremix]

Hi All,
Fairly new to this however I did previously monitor this old system using Unitrunker but now coming back to it using sdrtrunk and running into some problems locking onto a control channel.

The system I am looking to monitor is a P25-1: Alberta First Responders' Radio Communication System (AFRRCS) Trunking System, Multiple Locations, Alberta
Specifically the Edmonton / St. Albert site.
I have tried both with C4FM and LSM (LSM seemed to work better slightly)

I have loaded the system into sdrtrunk via RadioReference and have gone about it two ways:
1. Single Control Channel
Run the system and it just sits on the control channel idle, I did notice that it changes the frequency slightly to a different one from the actual control frequency inputted - nothing comes through

2. All control channels + alternates
Run the system and initially it was locking onto control, briefly bringing calls through then nothing - control channel looks to just be bouncing between all of the possibilities not locking onto the system.

The screenshot attached shows the system running on the single control channel, not sure if I have a bad signal or too much noise?
Any tips would be much appreciated.

 

[maus92]

S/N ratio looks poor - are you near any cell towers? Can you screenshot the Channels tab in the Playlist editor?

 

[emptyremix]

S/N ratio looks poor - are you near any cell towers? Can you screenshot the Channels tab in the Playlist editor?

Didnt even think to check for cell towers after I moved, sure enough right behind me in the alley is one 1900 MHz - 2100Mhz. am I hooped here? I see often fluctuations in the noise floor but I am able to pick up other AM / FMN frequencies nearby pretty clearly.

Screen shot included showing the channel tab, the one running has the single control channel currently.

 

[maus92]

C4FM is for multicast sites; LSM is for simulcast sites. Can you post your Tuners page? Did you adjust the SDR gains and the ppm? As far as cell site interference, I'm more concerned about adjacent channels just below 768 MHz, but a very close-by site in another band *might* cause an issue.

 

[chrismol1]

that ppm is +93.0 on autoadjust. no idea how that happens, Ive never had an RTL SDR go that major of an adjustment, typically 1.0-2.8

try to adjust the gain control master to automatic, see if it does anything different enough to at least stabilize lock on the control channel

 

[maus92]

Yea, it needs to be 0.0ppm or as close as you can get. Although I use autocorrect, I also manually adjust the ppm to zero it out.

 

[emptyremix]

I appreciate all the help, it looks like things have settled and I am locked onto control with a massive amount of calls coming through.
I'm thinking a combination of C4FM being the correct as well adjusting my gain a bit to clean up some noise.

Automatic Gain control just blasted me with noise, I did re-check my PPM and they are correct at that high of a value anything else I'm way off the mark, but I do see the Auto PPM doing some dine adjustments as it runs.

I think now I just need to mute some of the talk groups to clean up the calls and I'm set.

Thanks again!