SDRuno and DMR decoding with DSD+
Posted: 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?
- 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?