DSD+ Question For DMR

[G0HLJ]

A friend of mine who live 20 miles away has an ICOM R8600 which is connected to the internet via an ethernet connection.
In my shack, I use the ICOM Remote software to tune and listen to his receiver remotely which works great.

Obviously when I land on a DMR signal, I an hearing the uncoded audio.

Question:
Does anyone know how I could use, or even if its possible to use DSD+ to decode the DMR audio which I can hear through my speakers.



Ian

 

[rabrol]

You could use a Virtual Cable like VBCable to pipe the DMR audio into DSD+.
You'll have to set up DSD+ to be looking for audio on the Virtual Cable channel though. It will then output decoded audio to your speakers.

It has been a few years since I did this in DSD+, and it worked then. I haven't used any Icom remote software, but I expect the principle will be the same, providing you can tell the Icom software to output audio to the Virtual Cable instead of your default soundcard.

 

[G0HLJ]

I have got a little further but still unable to get DSD+ to decode the DMR

My Setup:
Both the ICOM Remote software and DSD+ is running from a Windows PC which I am connecting to using Team viewer (Remote Desktop) from my MAC. In the Windows PC, I have a pair of headphones connected to the headphones socket.

I have now ported the Audio from the ICOM software to VB-Audio and I can now see AF activity which is a DMR signal



In DSD+ I have set the input device to VB-Audio and the output device to the headphones but for some reason I cannot get DSD+ to start decoding. I was wondering if the audio going into DSD is overpowering the decoder or if there are any filters I need to set somewhere is DSD+

 

[rabrol]

It looks like the Icom might provide a virtual audio feed based on the screenshot above. That might work better than the Virtual Cable, but like I mentioned, I had no problems using VBCable.

I am assuming you are listening to the Amateur Radio repeater shown in your first post. If you are tuned to a commercial DMR frequency, you may be parked on a trunking control channel that is not presently carrying any audio traffic. Do you know if the frequency you are monitoring is active with voice traffic when you are listening? A DMR signal on its own does not necessarily mean that voice traffic is taking place.

 

[cg]

And you are getting the audio from the speakers then into the computer? Because DSDPlus would need discriminator audio and then I would wonder how much the computer soundboard, network and back through another computer would filter/alter that audio stream unless it is all setup to do just that.
You can link FMPxx to DSDPlus over the internet but as far as I have ever heard, not to any other software at the source location.

chris

 

[G0HLJ]

It looks like the Icom might provide a virtual audio feed based on the screenshot above. That might work better than the Virtual Cable

I have tried setting the input of DSD to the ICOM Virtual Audio


These are my Windows 10 settings, although it's a long tome since I used Windows, I think I have the settings correct unless anyone can see any issues.



Playback Settings


Record Settings

 

[G0HLJ]

I am now seeing data outputting to DSD+ and the Event Log is showing information but still not getting the decoded DMF. I feel I am so close to getting this to work, I must be missing something simple here.

 

[rabrol]

Looks like you are indeed getting close! You were able to read the TalkGroup and Radio ID. I would carefully play with your input / output levels, and do some fine tuning.

 

[G0HLJ]

Looks like you are indeed getting close! You were able to read the TalkGroup and Radio ID. I would carefully play with your input / output levels, and do some fine tuning.

Thats my next task. Interestingly enough is that if I put the radio into WFM then I sometimes get decoded Audio. Does anyone know why WFM would sometimes decode but NFM will not

 

[slicerwizard]

Input audio level is far too low. Decoding is full of errors.

 

[G0HLJ]

Input audio level is far too low. Decoding is full of errors.

Would that be something I adjust in DSD using the -g switch

 

[slicerwizard]

No. The audio going into DSD+ is low. Fix it at the source, if possible.

 

[LD723]

I would also try to reverse the polarity incase it still does not decode audio so in that version of dsdplus you would be using the command -p I think it was.

 

[G0HLJ]

Having spent some time investigating as to why the DMR will not decode I think I may have the answer.
The ICOM R-8600 has 3 Filter presets on NFM which are 7k, 15k and 50k and these cannot be changed.

For DMR I think I need 10k bandwidth which is probably why DSD+ is unable to fully decode the audio

 

[slicerwizard]

No, that's not it. DSD+ needs raw unfiltered flat audio. Your audio appears to be filtered.

 

[G0HLJ]

No, that's not it. DSD+ needs raw unfiltered flat audio. Your audio appears to be filtered.

Ah, I didn't know that but as I am stuck with using one of the presets in the 8600 I guess there is nothing I can do

 

[LimaZulu]

Solution may be far more simple than this if your friend's computer has rtl-sdr, static ip and DSD installed. He only has to tune FMP/FMP24 to desired frequency on port 20001 for example. On the other end you set your DSD to listen to his IP on the port he set (20001 if you follow the example). I used to do that with my home pc and my pc at work.
Only downside is that FMP/FMP24 accepts only one connection meaning that you can't run multiple DSDs connected to one FMP/FMP24