No P25 audio

[Matt Tottle]

Ok so it's been a few years since I've played around with SDR, and a LOT has changed since then so I'm pretty much rookie..  I got some Nooelec txco sticks, and a few hiccups aside, everything is now working - except the audio.  I can lock the control channel just fine, I can see the activity on the waterfall and in the Now Playing list, but no sound happens.  The log says JMBE is loaded, and the audio test in the control panel makes sounds - plus if I add a random FM frequency I hear static.  What did I miss?

Also is there anything special I have to do to make it use all three receivers or does it just do it?  Only one shows as "locked", does it just use the other ones when a frequency is out of the first tuner's range?

Thanks!

[Douglas Welch]

did you download and build jmbe lib?

its a seperate reposiotory you need it for p25

super simple to build with jdk 13 installed

gradlew build

[Matt Tottle]

Yup.  In the log screenshots you can see it loaded successfully.

[Ron Murray]

You didn't tell us what system / type of system you are trying to listen to. There's no screen shots of your channels set-up. Is it a P25 Phase 2 system ? If so, one of the other common user errors for P25 Phase 2 is that under the channels tab, decoders section, the control channel decoder MUST be set to P25 Phase 1. You would only use the Phase 2 decoder if you were trying to listen to the non-control channel frequencies.

The answer to your other question is yes, the software will use the other sticks as needed.

[Matt Tottle]

It's phase 1.

[Douglas Welch]

try posting your other tab screens, including "Messages." On "Events" screenshot shrink columns down so we can see more of the details column at far right.

i see one call being made to 4612 and thats it.

do you get any type of audio while listensing?

On Monday, April 27, 2020 at 9:09:09 PM UTC-5, Matt Tottle wrote:

[Matt Tottle]

That was the only call at that second.  No I get no audio at all.  I don't have any other system to try but as I said if I add a random FM channel and start it, I get static.

More screenshots enclosed

[Ron Murray]

That last screenshot of your channels tab appears to be set-up incorrectly for a trunking system. 

For Channels - Source change that to "TUNER", then enter your Control Channel frequency, then select your dongle too be used.

For Channels - Decoder, select P25 Phase 1, then select Simulcast (if that's the type of system you are monitoring) or C4FM if not.

[Ron Murray]

You do not need to enter each of the individual frequencies on a trunked system, only the control channel. The software will follow automatically.

[Matt Tottle]

There are multiple control channels, not just one. It is already set to phase 1/C4FM.  It is not simulcast.  Honestly if it were something to do with the system, I highly doubt it would show activity.  It is locking onto transmissions and creating the scratch channels for them, it's just not playing the audio.

[Ron Murray]

Is this the system you are trying to listen to ? https://www.radioreference.com/apps/db/?sid=4390

If it is....there is only one control channel for each site, the other channels listed for a site are the voice channels and maybe an alternate control channel.

[Ron Murray]

If you are trying to listen to the Hays site 2.2, the control channel is 852.3625 and that is the only channel you need in your channel configuration.

[Matt Tottle]

I tried it like that to begin with.  It doesn't work like that either. That's why I added the rest.  I just changed it back to single.  It still doesn't work.  Can we get off it being the system please? Because it's obviously not. Like I said, it is obviously working because it is locking on calls and assigning temp channels. It is just not playing the audio.

Thanks.

[Ron Murray]

Sure can. Just trying to help you troubleshoot as you asked. Good Luck.

[Matt Tottle]

I'm not trying to be rude, but all I have done so far is basically repeat everything that was in the original post, and I have gotten nowhere.  The first thing I got asked is if the JMBE library was installed - which I said in the OP (and posted a screenshot to back it up) is built and successfully loaded.  Everything else has been things that had they been set incorrectly the system would not be working at all.  You asked for screenshots of the Events and Messages tabs, which I posted, proving the system is working fine - yet you keep telling me to change things related to the system which if they were set wrong it would not be able to read the system at all.  It is frustrating to keep having to repeat myself. 

[Dave M]

The screenshots you've posted show nothing in the waterfall on the 'traffic' channels, so it's almost certainly something to do with the config of the system in there. The control channel is set up fine since it's processing events, but it's not mapping the right voice channels to the right frequency. In your first screenshot you can see actual traffic around 852.9 while it's tuned to 852.55.

I got no ideas beyond that, but that's 100% where you should be looking.

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[Matt Tottle]

Considering there is literally nothing to configure beyond the control channel frequency and decoder, Im not seeing how that is possible.  Ive got the offset corrected to within 0.1ppm so it's not the tuner.  Im now noticing that green band (KTHP?) in the spectrum does show up in the right place based on the call, but does not line up with the received transmission in the waterfall.  What else could cause it?

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[Dave M]

Possibly bad system configuration on the actual system side, as in by the admins of that trunking system? If you have a look in the details tab of the control channel near the bottom you can see what data it's sending as the channel info, that's what SDRTrunk uses to map channel number to frequency. That data is all broadcast from the system itself, so if it's bad then not sure there's anything that can be done on your side. Are there any neighbouring sites within range of your antenna? Could try one of them, see if they have the same problem.

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[Matt Tottle]

The next closest site is 20 miles away, and I cant pick it up.  However my hardware scanner picks this site up just fine, so it's not misconfigured..

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[Tracy KO7B]

I also have everything set up correctly, show audio waveform in the scope of the voice tuner(s) but no audio out on a P25P1 system using the latest 0.4.0 build.  I can use Unitrunker on the ame system and it works fine with good audio on the same talkgroups. I'm about ready to deinstall and reinstall from scratch - that fixed it once before. :(   Tracy

[Ronen Pinchuk]

I would also try to get another  JMBE   lib   i have seen  JMBE lib that  didnt  produce sound 

try and  get a compiled lib if you are not familiar with compilation or  compile another lib 

R

בתאריך יום שלישי, 28 באפריל 2020 בשעה 05:09:09 UTC+3, מאת Matt Tottle:

[sdrtrunk]

Matt,

Sorry you're having issues trying to get this to work.  Keep at it, we'll get it working.

Something's misaligned with either your configuration or the sdrtrunk software.  

In your attached screenshot in the spectral display, there are what appears to be the control channel at 852.3625 and two traffic channels (one starting and one ending).  I highlighted where the traffic channel signals are showing and where they should be showing on the frequency axis.  Both traffic channels appear to be off by about .3875 MHz.  This is why you're not hearing any audio.

Two things could possibly be causing this: 1)the tuner PPM is out of adjustment, or 2)The software is confused about the tuner's sample rate.

I discovered a bug that's preventing correct display of multi-frequency channel configurations on the spectral display.  That's why it's not showing a channel overlay on the control channel spike in the spectral display.

I need you to:

1. Change your channel configuration to use just the single 852.3625 control frequency.

2. Start the channel.

3. Make sure the now playing channel state changes to CONTROL (orange).  Adjust the tuner PPM if necessary to make this happen.

4. Wait until a call starts and take a screen shot.

5. Post the screenshot.

This should show us: 1) the control channel signal spike to frequency label alignment is correct and 2) the traffic channel signal spike to frequency alignment is correct (or not).

Thanks,

Denny 

[Matt Tottle]

Hey thanks.  Yeah I've tried fiddling with the ppm but that throws the control channel off.  It is measuring ~0.1ppm error  The control channel is dead on the money, and the voice channel indicators are popping in the right places, but the received signal isn't aligning with it.   Here's new screenshots.  I had also posted about this in the Discord, and I prefer to use that.  Thanks

[Matt Tottle]

Well, we got it figured out. The site listing in the RR database had the wrong control channels listed, and I was correcting the tuners to the wrong frequency. Not exactly a PEBCAK but it's still embarrassing lol. Update ticket has been submitted to RR so it doesn't happen to anyone else.   Thanks Denny!