SDR Trunk v0.5.0 Alpha 3 - No Audio

mike_s104

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Just started using my SDRs again. I have 2 Nooelec NESDR Mini 2 R820T2's. I used SDRconsole to change the serial number on one of them so I would be able to tell them apart. I figured out that the PPM needed to be set to 65 for the freq offset. I have the JMBE Audio Library configured/compiled. The one tuner locks onto the CC and will show that there are active transmissions. Very occasionally I will get some audio but mostly not. I've tried other systems (VA STARS) and it acts the same way. Any suggestions?
 

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BM82557

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I'm still using V0.4.0 final most of the time. I haven't had any problems with 0.5.0 A3 when I've tried it.
 

lwvmobile

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Have you tried just locking on to that control channel with one dongle, and leaving the other dongle free (not using in on a second channel)? Either that, or change the C4FM/Simulcast option if you are looking at P1. Not sure if that'll help, but maybe a few things to look at.
 

maus92

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Just started using my SDRs again. I have 2 Nooelec NESDR Mini 2 R820T2's. I used SDRconsole to change the serial number on one of them so I would be able to tell them apart. I figured out that the PPM needed to be set to 65 for the freq offset. I have the JMBE Audio Library configured/compiled. The one tuner locks onto the CC and will show that there are active transmissions. Very occasionally I will get some audio but mostly not. I've tried other systems (VA STARS) and it acts the same way. Any suggestions?
The ppm of 65 seems huge to me, considering mine is 0.4 for a Nooelec Black - although Nanos are not tcxo'd.
 

air-scan

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The ppm of 65 seems huge to me, considering mine is 0.4 for a Nooelec Black - although Nanos are not tcxo'd.
My Nano3 has a TCXO

Just started using my SDRs again. I have 2 Nooelec NESDR Mini 2 R820T2's. I used SDRconsole to change the serial number on one of them so I would be able to tell them apart. I figured out that the PPM needed to be set to 65 for the freq offset. I have the JMBE Audio Library configured/compiled. The one tuner locks onto the CC and will show that there are active transmissions. Very occasionally I will get some audio but mostly not. I've tried other systems (VA STARS) and it acts the same way. Any suggestions?
Check to be sure you have all the frequencies listed for that system and if it is simulcast make sure LSM is toggled on in the Channels tab. LSM for simulcast systems and C4FM for others. Don't forget to press the save button if you need to make these changes.
 

maus92

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LOL, I misread the OP's post, although his Mini 2's are not TCXO - but the Mini 2+ is. Same with Nanos: prior to version 3, the Nano v1 and v2 are not TCXO. I briefly used a Nano for a 24/7 logging with Unitrunker, but that SDR burned up after a few months - got way too hot, and they don't have enough surface area to dissipate the heat. It was replaced by Nooelec Black v3 and v4 SDRs, but I recently had one of those burn up as well.

Perhaps his SDRs are drifting after warming up.
 

air-scan

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The OP stipulated 65ppm which looks centered well in their screenshots. One often missed setting is the LSM/C4FM switch in channels tabs which would cause missed transmissions if not set correct to the system. LSM has to be toggled on on a simulcast system or no audio and missed calls.
However, as the mini 2+ warms up then the OP should go to the Tuners tab in the main window and manual adjust for the lowest ppm reported in the column of tuners. SDRTrunk does a good job displaying in hertz the frequency offset from center which should be set for lowest possible. It won't be perfect but it does improve decodes performing the task.
LOL, I misread the OP's post, although his Mini 2's are not TCXO - but the Mini 2+ is. Same with Nanos: prior to version 3, the Nano v1 and v2 are not TCXO. I briefly used a Nano for a 24/7 logging with Unitrunker, but that SDR burned up after a few months - got way too hot, and they don't have enough surface area to dissipate the heat. It was replaced by Nooelec Black v3 and v4 SDRs, but I recently had one of those burn up as well.

Perhaps his SDRs are drifting after warming up.
 

mike_s104

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The OP stipulated 65ppm which looks centered well in their screenshots. One often missed setting is the LSM/C4FM switch in channels tabs which would cause missed transmissions if not set correct to the system. LSM has to be toggled on on a simulcast system or no audio and missed calls.
However, as the mini 2+ warms up then the OP should go to the Tuners tab in the main window and manual adjust for the lowest ppm reported in the column of tuners. SDRTrunk does a good job displaying in hertz the frequency offset from center which should be set for lowest possible. It won't be perfect but it does improve decodes performing the task.
I think they have drifted all they are going to right now. I'm using one with Unitrunker. The CC is 460.1625 but I need to set it to 460.364 to decode anything.

I did try changing from C4FM to LSM and it made it worse.
 
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air-scan

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I think they have drifted all they are going to right now. I'm using one with Unitrunker. The CC is 460.1625 but I need to set it to 460.364 to decode anything.

I did try changing from C4FM to LSM and it made it worse.
I still have my old Nooelec black dongle with MCX connector no TCXO it's 6 years old. I used to have to keep setting ppm until it stopped drifting.
 

mike_s104

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Just got my NESDR Nano 2 Plus in the mail. It's a lot more accurate than the others. I ordered 2 more to see if I can get SDR Trunk to work.

I think the audio I was heading was from another system.
 

air-scan

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Just got my NESDR Nano 2 Plus in the mail. It's a lot more accurate than the others. I ordered 2 more to see if I can get SDR Trunk to work.

I think the audio I was heading was from another system.
Try to get the column that says Measured Error lowest as possible. It'll be average. Really hard to get a perfect error of 0 hertz, for mine I managed to get lowest possible average. What I do is set ppm leaving auto correction on to obtain this. SDRTrunk works with it pretty good.
rtlsdrppmsdrtrunk.png
 

mike_s104

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Just got my NESDR Nano 2 Plus in the mail. It's a lot more accurate than the others. I ordered 2 more to see if I can get SDR Trunk to work.

I think the audio I was heading was from another system.
So I looked at another system close by and that is in the 460MHz range. The one TG that SDRTrunk was showing and decoding audio for was Washington Co. MD. So I'm guessing that when the one SDR was locked onto the CC with the PPM set, the other was trying to tune to the correct voice freq and got a freq used for this system and just happened to be in use at the time.Screenshot 2020-10-08 074756.jpg
 
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