SDRuno and DMR decoding with DSD+

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StandingWave
Posts: 56
Joined: Mon Feb 18, 2019 6:54 pm

SDRuno and DMR decoding with DSD+

Post by StandingWave » Sun Apr 28, 2019 8:18 am

I recently tried decoding some DMR signals from a couple of local amateur radio repeaters. I used an RSP2 as well as an RTLSDR, an SDR program, a virtual audio cable and DSD+. I used the same process will each program:

- set audio out in the program to the virtual audio cable
- choose the virtual audio cable as inout in DSD+
- choose the appropriate audio output in DSD+ (headphones)
- use antenna B on the SDRplay, the VHF/UHF antenna on the RTLSDR
- set the SDR program to FM modulation, NFM mode and a 12.5kHz filter
- start and tune the SDR radio and watch the output on DSD+

I found that I could decode DMR using HDSDR or SDR# but not with SDRuno 1.31. I tried using both VAC and VBcable for the virtual audio cable and tried with both an RSP2 and an RTLSDR radio. In SDRuno, other than the startup messages, I got no data at all showing in the command window, whereas in HDSDR and SDR#, data started flowing as soon as the repeater frequency was tuned and I was able to tweak the sound levels in control panel to get reliable decoding into audio.

After scratching my head over this for a while I accidentally discovered that in SDRuno, the mode has to be set to WFM, not NFM or even MFM. When set to WFM Data then flows and is decoded into audio. I simply used the narrowest filer (60kHz) for that mode as that was the narrowest option available in this mode, but not really ideal. When NFM or even MFM is selected, there is simply no data being presented to the decoder. I also tried experimenting with the SDRuno DSB, DIGITAL and IQ modes, but none of these modes yielded any results either.

Does anyone at SDRplay know what is going on here?

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g4enz
Posts: 40
Joined: Tue Nov 29, 2016 1:17 pm

Re: SDRuno and DMR decoding with DSD+

Post by g4enz » Sun Apr 28, 2019 12:53 pm

StandingWave,

Don't abandon hope. I use SDRuno to receive DMR from local 70cms repeaters and then pass it for decoding to DSD+. I use NFM and a 10kHz bandwidth. Contact me directly if you want to compare settings.

73 Martin - G4ENZ

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StandingWave
Posts: 56
Joined: Mon Feb 18, 2019 6:54 pm

Re: SDRuno and DMR decoding with DSD+

Post by StandingWave » Sun Apr 28, 2019 1:57 pm

G4enz, thank you. Can I ask which version you are using? I’m using the most recent, 1.31, but was going to try an earlier version to see whether it has the same problem. If what you are using works, then I will try that version. Interesting too that you use a 10kHz bandwidth. I was told that approx 12.5kHz is required, but will try 10kHz as well.

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pnoelw
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Joined: Sun Feb 19, 2017 2:07 pm

Re: SDRuno and DMR decoding with DSD+

Post by pnoelw » Sun Apr 28, 2019 2:32 pm

Hi Standingwave
i haven't used DSD or tried to decode DMR - however, i have found by trial and error that various digital modes require different settings on the desktop radio software and it can be very frustrating.
When using NFM have you tried turning de-emphasis off? When decoding Pocsag and Flex with PDW (fed from SDRUno using VBaudio cables) i have found that Flex works well with de-emphasis off but Pocsag will only decode with de-emphasis on 75us. In both instances i use NFM with the filter bandwidth between 15kHz and 20kHz.
Please let us know how you resolve this as i would also like to try DSD+ in the near future.
Noel.

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Martien
Posts: 9
Joined: Wed Mar 06, 2019 1:48 am

Re: SDRuno and DMR decoding with DSD+

Post by Martien » Sun Apr 28, 2019 4:45 pm

Hello,

In this topic I gave my settings for decoding DMR with DSD+ 1.101:

https://www.sdrplay.com/community/viewt ... f=5&t=4181

Works well for me, hope it helps.

Best regards,

Martien, PD1G
Last edited by Martien on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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g4enz
Posts: 40
Joined: Tue Nov 29, 2016 1:17 pm

Re: SDRuno and DMR decoding with DSD+

Post by g4enz » Sun Apr 28, 2019 7:38 pm

StandingWave,

I am using V1.31 but have used all versions since I first started DSD+ with SDRuno 1.24. I recently paid to subscribe to the "fast lane" version of DSD+ and I am now decoding Fusion and D-Star as well as DMR. D-Star will work in 8kHz but DMR is slightly wider. I tweak the bandwidth as I go along but DSD+ is reasonably tolerant of running narrow bandwidths. On a strong signal, copy starts to fail at less than 8kHz.

73 Martin

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StandingWave
Posts: 56
Joined: Mon Feb 18, 2019 6:54 pm

Re: SDRuno and DMR decoding with DSD+

Post by StandingWave » Sun Apr 28, 2019 9:47 pm

Martien wrote:Hello,
In this topic I gave my settings for decoding DMR with DSD+ 1.101:

https://www.sdrplay.com/community/viewt ... f=5&t=4181

...
Martien, PD1G
Thanks very much for this. The following two settings were crucial:

- SDRuno EX control
DEEM: OFF
50uS and 75uS: OFF

Setting these made the difference, in particular DEEM : OFF. Setting this to ON kills the flow of data to DSD+ when either NFM or MFM are selected. Turning it OFF and using a 10kHz filter in NFM mode now works nicely.

Interestingly I just got this as momentarily as well:

Sync:+NXDN96 CS VOICE e:5r6r6r5m
Sync: no sync
Sync:-NXDN96 TB DATA
Sync: no sync
Sync:+DMR

Did it pick up some NXDN for a moment, or was that mis-identified?

It works better with VAC as one can tweak the volume level to get the best decoding output.
Just been listening to someone in Tel Aviv talking to someone in the USA!

BTW, anyone know what the signal with the dotted line is on the right of the waterfall at 440.200MHz? It seems to be there constantly regardless of the time of day I fire up SDRuno.
Attachments
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Martien
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Joined: Wed Mar 06, 2019 1:48 am

Re: SDRuno and DMR decoding with DSD+

Post by Martien » Mon Apr 29, 2019 9:36 pm

Good to hear you got it working, I think the NXDN was mis-identified if you're still on a DMR channel.
Don't know about the 440.200, frequency is clear here in the Netherlands.
Over here there are a lot of NXDN signals between 460-470 mhz, maybe it's the same where you are and you can have a look at decoding them.

Best regards,

Martien, PD1G
Last edited by Martien on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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StandingWave
Posts: 56
Joined: Mon Feb 18, 2019 6:54 pm

Re: SDRuno and DMR decoding with DSD+

Post by StandingWave » Tue Apr 30, 2019 12:19 pm

Martien, thanks. I had a look at that frequency range, but it seems mostly clear over here. I will have another look later in the evening. It might also be that I need a better antenna for that frequency range.

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StandingWave
Posts: 56
Joined: Mon Feb 18, 2019 6:54 pm

Re: SDRuno and DMR decoding with DSD+

Post by StandingWave » Thu May 30, 2019 10:59 am

Thanks but doing a search on here was able to find only one other post which was just a passing reference.

Having searched online, I found SDRAngel, SDRAngelove and rtl-SDRAngelove. Not sure which one to use, but I cloned the first one. I must admit to being put off by the size of the package and the very extensive list of dependencies. Looks like this is going to be a long and complicated compile process so I will have a go when I have plenty of time.

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