SDR#, VB Cable and DSD - DMR Test File

[M7THW]

I'm trying to get SDR# to output to DSD, and for DSD to decode. I think I've got everything set up right, but DSD doesn't output any lines... It just sits with:

"Digital Speech Decoder 1.7.0-dev (build:v1.6.0-86-g7ee04e5)
mbelib version 1.3.0
Audio In/Out Device: /dev/dsp"

Does anyone have a recording of a digital signal that DSD has no problem decoding? - I'm not sure if I'm just having trouble finding a compatible signal.

Thanks

 

[LimaZulu]

I do not have any record to give you for testing at this moment but maybe you can share with us your setup, so we can spot any possible mistake.
At first I can point you to a few settings that should get you going - set sdr# output to vb cable, turn off audio filter, set vb cable as default recording device, start dsd with -fr (I believe that was for dmr) switch

 

[dave3825]

Does anyone have a recording of a digital signal that DSD has no problem decoding?

Here is a brief conversation on Con Plus system

 

[M7THW]

I do not have any record to give you for testing at this moment but maybe you can share with us your setup, so we can spot any possible mistake.
At first I can point you to a few settings that should get you going - set sdr# output to vb cable, turn off audio filter, set vb cable as default recording device, start dsd with -fr (I believe that was for dmr) switch

SDR# output set to VB Cable, audio filter ON, VB cable as default recording device. I'm opening DSD with "dsd -i /dev/dsp -o /dev/dsp -fa"

Yeah, -fr is for decoding DMR/MOTOTRBO only, -fa is auto-detect

 

[Ubbe]

You should see the signal in the DSD+ Source Audio window. It should be a random noise wave going over the whole display when not receiving any signal and probably squelch in SDR# needs to be set to none. If it doesn't show anything in that window then the audio are not connected between SDR# and DSD+

/Ubbe

 

[LimaZulu]

You should see the signal in the DSD+ Source Audio window. .....

He is using DSD 1.7, not DSD Plus

 

[Ubbe]

He is using DSD 1.7, not DSD Plus

It would be easier for him if he switched to DSD+ during the setup process to see that it works with the VB cable. It's lot easier if you can see on the display that audio are arriving at a proper level to the decode process.

/Ubbe

 

[dave3825]

It would be easier for him if he switched to DSD+ during the setup process to see that it works with the VB cable.

I was just coming back to post the same thing. Lol

 

[M7THW]

I think SDR# isn't outputting to the VB Cable.

To test this, I had the Con Plus file (thanks @dave3825) playing in SDR# and made a recording in Windows Voice Recorder - I didn't get anything recorded in Voice Recorder, even though VB Cable is set as default recording device.

I then opened up Windows Settings --> Sound --> Manage sound devices, and clicked 'Test' on the VB cable output device. This test sound came through the VB cable and into Windows Voice Recorder.

So it must be SDR# not feeding the VB Cable

 

[LimaZulu]

Probably but maybe there is a reason he wants to use open source decoder.

 

[M7THW]

Confirmed: SDR# is not outputting to the VB Cable - If I open up the VB Cable Control Panel, I can't see any signal level on the meter. So nothing going through VB Cable.

If I play the DMR recording from Windows Media Player, DSD will decode it and output from the speakers.

 

[dave3825]

So it must be SDR# not feeding the VB Cable

I think SDR# isn't outputting to the VB Cable.

How are you attempting to output from sdr#? Are you selecting vb cable in the audio output tab or are you using the dsd plus plug in? Also, there is a filter audio setting in sdr#. That needs to be set NOT to filter audio..

 

[dlwtrunked]

I'm trying to get SDR# to output to DSD, and for DSD to decode. I think I've got everything set up right, but DSD doesn't output any lines... It just sits with:

"Digital Speech Decoder 1.7.0-dev (build:v1.6.0-86-g7ee04e5)
mbelib version 1.3.0
Audio In/Out Device: /dev/dsp"

Does anyone have a recording of a digital signal that DSD has no problem decoding? - I'm not sure if I'm just having trouble finding a compatible signal.

Thanks

I have found for DSD+ to decode a local DMR, the gain has to be see rather low. Try turning down the level of the 3 countrols that control gain in DSD+. If I set those high, I see no decoded.

 

[M7THW]

How are you attempting to output from sdr#? Are you selecting vb cable in the audio output tab or are you using the dsd plus plug in? Also, there is a filter audio setting in sdr#. That needs to be set NOT to filter audio..

I've since turned squelch off, and audio filter off - still no output.

I've not got the DSD plus plugin - will it work with DSD non-plus?

I'm just selecting the output in the 'Audio' panel.

EDIT: I've got it to work - I had NFM selected while playing the .wav file. After setting it to RAW, it works! Doh!

 

[dave3825]

I've not got the DSD plus plugin - will it work with DSD non-plus?

Plug in can work 2 different ways.

The plug in will work with anything if you only select enable aux audio output and select the vb or vac cable.




That just basically does the same thing as setting a vb or vac cable in the sdr audio out section.




The start dsd button goes to the dsdplus directory, sets your parameters and launches the dsdplus executable.




Glad you got it working.



.

 

[LimaZulu]

......

EDIT: I've got it to work - I had NFM selected while playing the .wav file. After setting it to RAW, it works! Doh!

If that's what sorts out your problem then bandwidth is what wasn't right. Either your NFM bandwidth setting was too low or too high. 9.5 should be ok for DMR. NFM is the right setting to be.

 

[francisuk29]

9.5 should be ok for DMR. NFM is the right setting to be.

12.5 is right for DMR as two slots take 6.25 = 12.5

Also keep in mind, 2x slots can be used at the sametime on DMR systems. You find Left speaker for slot 1 and slot 2 for Right.

 

[LimaZulu]

12.5 is right for DMR as two slots take 6.25 = 12.5

That is what books says but in reality where you try to utilize 3rd party device for radio use you find a lot of other dependencies That's why in general 9.5 is the rough bandwidth to start to play with in order to start decode properly

Also keep in mind, 2x slots can be used at the sametime on DMR systems. You find Left speaker for slot 1 and slot 2 for Right.

I do know that quite well, but don't know how is this related to the topic?

Anyways, this case was resolved some time ago. There is no need to dig it up

 

[M7THW]

The file provided by @dave3825 is already demodulated, right? So I don't want to run it through a filter or FM demodulator again.

So, I can get SDR# to output to DSD-1.7.0 now, but the decoded audio is very choppy and completely non-intelligible. I even drove to within 500meters of a DMR repeater, and perfect line-of-sight - same issue. I'll experiment with filter bandwidth as suggested by others. I was using 12.5KHz and the signal was about 15dB above the noise.

But I wonder if this is something DSD Plus would fix, or if this garbled audio is a known thing in DSD-1.7.0?

Also my DSD would only decode a few words in the file provided by @dave3825 - I can't make out any sentences. Does DSD Plus do a better job?

EDIT: Here is a WeTransfer link to a .mov video showing what the decode sounded like, and looked like: Bad DMR Decode

 

[M7THW]

Hi Dave, thanks for your detailed reply.

The plug in will work with anything if you only select enable aux audio output and select the vb or vac cable.

This sounds useful. Does this mean I can listen to the NFM demodulated DMR signal from SDR# out of my speakers, and use the aux to send the same signal into VB cable?