'Fade' status on what should be 'Call'

[Peter Fox]

Hello,

sdrtrunk v0.6.1 final, SDRPlay API 3.15, with SDR Play RSP1B.

I'm having an excessively high number of Fade status, for calls where it should be a voice call. Prior, I had API version 3.14 and sdrtrunk 0.6.1 beta 1. It didn't decode individual talkgroups from patch groups, but all calls were converted to audio great.

I started using 0.6.1 final, with api 3.14. I thought it worked great for a few days, but have users complain of missing audio. I go look, and see lots of Fade status. So I updated my API to 3.15, I think I have some improvement but still getting lots of fade.

Thing is, If I run 0.6.1 beta 1, all calls are converted to audio great, but as soon as i try 0.6.1 beta 2 or beta 3, I have the channel fade problem.

Not really sure where to go from here.

[Caitlin S]

sounds like the PPM correction is off, while viewing the spectrum of each tuner, adjust the signal to fall within the bandwidth markers using the PPM corection

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[Peter Fox]

I (had) it set to auto-PPM. It appears centered. I've toyed with it in manual mode, like the screenshot, but it appears centered to me.

[charley....@gmail.com]

Your ppm is off by 0.9ppm, so change your error correction setting to -0.9. 

[Peter Fox]

Well you are correct, thank you!

Although I can't visibly see a change in spectrum view.

So then, is it a bug that SDR Trunk isn't auto correcting itself?

[wemana...@gmail.com]

On Thursday, May 22, 2025 at 2:33:30 PM UTC-4 pmf...@gmail.com wrote:

Hello,Thing is, If I run 0.6.1 beta 1, all calls are converted to audio great, but as soon as i try 0.6.1 beta 2 or beta 3, I have the channel fade problem.

Not really sure where to go from here.

 
Curious as to your setup as this mimics an issue I have.

Is this for Phase I or Phase II calls, or both?

System type? Ie: Motorola or Harris (L3/nom du jour)

Trunked system is it PURE Phase I or Phase II? Meaning NO calls in either type or mixed?

I see you are using the SDRPlay's, are these actual ones or clones?

Have you tried it with a RTL-SDR V3 device or Airspy device? HAckRFOne?

Are these local systems? ie: Distance to tower?  Terrain? You need not give a exact location, I wouldn't ever ask that in public.) Have you tried with a similar laptop setup near a tower site?

Antenna type and setup ie: a 850MHz omni 30 feet up, on 50feet of LMR 400 etc..

My problem is like yours as soon as I move to 0.6.1 B2 or B3 all PII decoding fails. Switch BACK 0.6.0f or 0.6.1b1 which I am running now, seems to resolve it..

My OP25 setup on a Pi3 on the SAME antenna system works fine.

I've tried V3;s, HackRFOnes, SDRPlay Clones, and AirSpy Mini and R1/R2's...ALL fail on 061b2/3... on all sorts of hardware too. And all kinds of antenna setups. ALL MIMIC your results.

I have both a 2 Harris and a Moto system with PII... and it works in my current setup.. 2 are local, and 1 is "local" but i am not the primary coverage area, and OP25 when used on this was great. I've actually considered going back to it... but i would take too many Pi's and SDR's to do that with OP25 the way it works.

So I'd be interested in hearing some more details on your seupt and systems to see where the overlap is. 

I think something in the PII decoder changed which impacts certain PII setups... I've got a hunch, but I don't want to go any further as not to jade this.

Thanks, and I look forward to more info.

[Peter Fox]

Please see answers below in red. Really, it seems your trying to figure out why your's isn't working. Perhaps you should start a separate thread? What signal strength are you getting from control channel? does it rise above noise floor? are you using C4FM or LSM mode? Calibrated CPU vecors? tried heterodyne and Polyphase?

On Friday, May 23, 2025 at 5:48:12 PM UTC-4 wemana...@gmail.com wrote:

On Thursday, May 22, 2025 at 2:33:30 PM UTC-4 pmf...@gmail.com wrote:

Hello,Thing is, If I run 0.6.1 beta 1, all calls are converted to audio great, but as soon as i try 0.6.1 beta 2 or beta 3, I have the channel fade problem.

Not really sure where to go from here.

 
Curious as to your setup as this mimics an issue I have.

Is this for Phase I or Phase II calls, or both? All calls are PII, control channel is PI.

System type? Ie: Motorola or Harris (L3/nom du jour) Harris https://www.radioreference.com/db/sid/10306

Trunked system is it PURE Phase I or Phase II? Meaning NO calls in either type or mixed?

I see you are using the SDRPlay's, are these actual ones or clones? My RSP1B is the real deal.

Have you tried it with a RTL-SDR V3 device or Airspy device? HAckRFOne? Long time ago, used genuine RTL-SDR, got frustrated by how many dongles I needed, so switched to AirSpy R2. I used that for a while, but eventually decided to upgrade to SDRPlay. It was an upgrade, better audio quality as a result.

Are these local systems? ie: Distance to tower?  Terrain? You need not give a exact location, I wouldn't ever ask that in public.) Have you tried with a similar laptop setup near a tower site?

Antenna type and setup ie: a 850MHz omni 30 feet up, on 50feet of LMR 400 etc.. I'm using a yagi, pointed to the nearest tower of the simulcast site I receive from. Its simply a amazon antenna for a cell phone booster.

My problem is like yours as soon as I move to 0.6.1 B2 or B3 all PII decoding fails. Switch BACK 0.6.0f or 0.6.1b1 which I am running now, seems to resolve it.. Please refer to previous replys, others suggested I adjust my PPM. Since I have manually adjusted it down, SDRTrunk shows PPM deviation to be 0.0. Since doing this, I have had NO TROUBLE, everything works as supposed to. I've never needed to manually adjust PPM before.

[wemana...@gmail.com]

On Saturday, May 24, 2025 at 12:08:01 PM UTC-4 pmf...@gmail.com wrote:

Please see answers below in red.

Whoops.. no colors here. I am on plain text. :)
 

Really, it seems your trying to figure out why your's isn't working. Perhaps you should start a separate thread? What signal strength are you getting from control channel? does it rise above noise floor? are you using C4FM or LSM mode? Calibrated CPU vecors? tried heterodyne and Polyphase?

 

'My setup works great. till 061b2 or b3... Then Phase II falls apart. Thanks, but none of this applies. Just for  info, all this is done, ...and I've put more power into this system than is needed 16 Cores 128GB, dedicated high speed USB card (has controllers for each port)

The ONLY CHANGE IS SDRTRUNK VERSION.

There is something in the 61b2 and later PII decoders which has changed. 

> All calls are PII, control channel is PI.

Match.

>  Harris

Match, and Motorola here. PII dies'

> Long time ago, used genuine RTL-SDR, got frustrated by how many dongles I needed, so switched to AirSpy R2. I used that for a while, but eventually decided to upgrade to SDRPlay. It was an upgrade, better audio quality as a result.

I tried the SDRPlay's, but I used clones, I got some deals, and they work quite well.. for my needs..

The reason I wanted to use Hack/Airspy/SDRPlays of some sort was bandwidth, unfortunately for me my systems span the 851 to 861 entirety of the band, for 3 of them, and 1 is  mix 700/851Mhz, don't even get me started on that fiasco (its the non local one)

>. I'm using a yagi, pointed to the nearest tower of the simulcast site I receive from. Its simply a amazon antenna for a cell phone booster.

For one system, I point a yagi at the site, I am NOT the primary zone, the PI calls all work great. The PII calls worked great till 061b2. Its only about 8 air miles to that site.. but again, its not designed to cover me.. the other sites are.

The signals are all -30db or so, same as in OP25, when used previously.


> Please refer to previous replys, others suggested I adjust my PPM. Since I have manually adjusted it down, SDRTrunk shows PPM deviation to be 0.0. Since doing this, I have had NO TROUBLE, everything works as supposed to. I've never needed to >manually adjust PPM before.

Thanks, bu PPM is NOT my issue. Period.

I've played with it manually, and it has no effect. I let SDRT auto adjust. Actually futzing with the PPM will kill the PI calls.

THE ONLY way to get PII to work on 3 PII systems is to reverrt to 061b1. Otherwise it fails.

The towers for all of these in 2 cases would be considered LOCAL., and its not PPM, as the only change when  done was SDRT version. I spent a lot of time pulling hair out, and on this, and finally had to accept reverting to 061b1 was the only choice. It makes no sense as to what changed in 061b2 and later.. but when nothing RTL V3, Airpsy's, HackRF's or SDRPlay will work on 61b2 or later in PII. Then its a program issue.

At this point I've pretty much resolved that 061b1 will be it .. heck my main production for one is 050b6 or something.. I've played with this setup long enough, and done some other much more drastic things to resolve that 061b2 and later don't work for PII on my 3 systems.  Disabling auto adjust will actually make things fall apart even using the PPM listed...

Your issue mimics exactly my issue, except the resolution is not PPM.

Thanks for the info,as things match up, except the resolution.

[dave38...@gmail.com]

@Pmf,  

This is what a good signal looks like. Notice the signal peaking way above the noise floor.

This is your signal which is barely above the noise floor and full of noise.  What antenna are you using and how far are you from the site?