SDRTrunk Fade Issue

[scottct1]

Not sure what's up, but I have been using SDRTrunk for awhile and it's been working fine.

Today however I use it and it will not tune to any of my talk groups. When a Talkgroup pops up the status goes from IDLE to FADE immediately.

Looking at the signal power I am getting around 23.4 which should be fine.

I uninstalled and reinstalled it... I even installed it on a new laptop and am getting the same thing... and it's orhappening no matter which trunk group I am using.
The Pink Colored ENCRYPTED seem to have no problem, but the unencrypted on always immediately say fade and I get no audio

For those wondering this is the Connecticut P25 CLMRN system.

Any ideas?

 

[hazrat8990]

How's the noise floor? I noticed that I was having a similar issue with one of the control channels I monitor. I messed around with antenna position, gain settings, installed ferrites on USB cable and coax. Nothing seemed to work and I was starting to get frustrated. All of this headache turned out to be the LED porch light!

 

[ChrisABQ]

I was having some issues with SDRTrunk also, mostly crashes. Try unplugging the SDR's and hub if you have one, restart and plug everything back in, it's like doing a SDR cache reset. Let me know if it works.

 

[scottct1]

I have restarted, reiserted, tried on a different laptop, Used different SDR devices and still not hearing anything... everything just says FADE when it tries to play... all was working great before and I didnt change anything.

I even took my machines to work today to see if it was some kind of interference issue. And having the same issues here.

On this machine I am on now all the tuner settings are default and I have not adjusted them at all.

Here is a screen shot.. from what I see it looks good and the signals look good to me, so maybe I am missing something.

 

[ChrisABQ]

Another thing you can try is going backwards through the older versions of SDRT and see if/when things may start to work again.

Releases · DSheirer/sdrtrunk

A cross-platform java application for decoding, monitoring, recording and streaming trunked mobile and related radio protocols using Software Defined Radios (SDR). Website: - DSheirer/sdrtrunk

github.com

 

[hazrat8990]

Another thing you can try is going backwards through the older versions of SDRT and see if/when things may start to work again.

Releases · DSheirer/sdrtrunk

A cross-platform java application for decoding, monitoring, recording and streaming trunked mobile and related radio protocols using Software Defined Radios (SDR). Website: - DSheirer/sdrtrunk

github.com

I was just going to suggest the same thing. I tried one of the newer releases of the nightly build and had issues with it freezing and a few other things. I ended up going back to the previous nightly build. This version seems to be the most stable so far.

 

[scottct1]

Thanks I will give those things a shot.

 

[dave3825]

Mine looks like this.



Yours looks like this




Post a screenshot of your tuners tab showing PPM and gain settings. Like this,

 

[freema22]

I am experiencing EXACTLY the same thing. It worked great for MONTHS and all of a sudden, it is deaf as a post. I can see lots of strong signals on the waterfall, and can hear them on my old Whistler 1065 that shares the antenna. SDRTrunk isn't hearing anything. I verified this on a separate computer with a different SDR, and experienced the same thing. I really believe it's a software issue.

 

[maus92]

Hmm, as @dave3825 illustrates, it looks like the sdr device has drifted off frequency. The ppm needs readjusting, and it's possible the sdr device is failing.

 

[doctorwizz]

I had this exact issue too on one PC. It has one RTL-SDR V3 dongle. Never needed 2.

Bought one more dongle. Same issue until I disabled the old dongle in SDRTrunk. It instantly worked So the old dongle is definitely bad. I will toss it. It was purchased 5-20-23.

I have a mini PC for broadcasting. It works fine and It has 2 V4 dongles that are one year old.

I hope this helps someone. This thread came up on a Google search for SDRTrunk fade.

 

[doctorwizz]

Well, I could be wrong.
I took out the old one. I am getting fade again.
I don't have to time to mess with this now.
Back later.

 

[doctorwizz]

Okay, I understand now after some testing

On my old V3 defective dongle, the Channel Spectrum looks like the the one scott1 posted above. SDRT will always show fade with this.

https://forums.radioreference.com/attachments/20240628_113219_screen_capture-png.164861/

The new V3's Spectrum looks perfect.

So, if I use the old defective V3, I get the fade.
Then, close SDRT, unplug the old V3. Plug in the new V3 and restart SDRT, I still get fade until it calibrates the PPM or whatever. Then after a minute or two, SDRT will start working normally by itself.

I aways use auto adjust PPM. It just works perfect for me. I have not tried to adjust PPM on the defective dongle. I don't think it would help but I will try some things just for fun

 

[dave3825]

The pic in the link posted shows ppm being off. Take what you think is the defective dongle and adjust the ppm and see what you get. If you have sdr# just tune to a known frequency and look at the spectrum. Is you find something like -1.5 centers it, use that setting in SDRT.

 

[doctorwizz]

I got the old dongle to work by changing the PPM. I thought it was auto? I didn't uncheck auto and set it like this:
Does this look ok?

 

[doctorwizz]

How do these get so much drift? This one worked fine for a year.

You can see in the above screenshot that I had to set PPM to -3.552. That was found by accident. No fade at all set like this.
On another PC that has 2 dongles, those are .053 and -0.83

 

[saioke]

How do these get so much drift? This one worked fine for a year.

You can see in the above screenshot that I had to set PPM to -3.552. That was found by accident. No fade at all set like this.
On another PC that has 2 dongles, those are .053 and -0.83

Are you using the same SDRTrunk build on that system as you are on the other PC? Just curious because I tried using the nightly a week or so ago and I had issues getting it to read my CC. Switching to the stable build fixed it.

But yeah, over time the PPM of these devices goes wonky due to heat and other factors. I'm pretty sure there's no way to avoid degradation and some ocellators are more susceptible than others. My brand new RTLSDR V4 had a PPM right from the get-go of about +2.3. Cheaper SDRs I'm pretty sure can reach the 30+/-

 

[doctorwizz]

I always use the latest nightly on this main PC which I built, it has a a RTLSDR V3. Mostly for testing and personal listening.

On the other PC which has 2 RTLSDR V4s, that is a Beelink mini PC that is for broadcasting, it usually has the latest nightly. Currently has 3-22-2025 nightly. 26 days uptime right now. This Beelink mini has been running 24/7 for 18 months so far.

Never had any issues with any nightly.

I copy the same config folder between these PC and have many backups of it.