DSD for Raspberry Pi

[clemfm]

Hello,

I did some more experimenting with a RPi 3 using Ubuntu 15.10. I used the command line rather than the GUI. Raspbian uses Hardware Float for the original RPi through RPi 3. Ubuntu 15.10 also uses Hardware Float (ARMHF). So the code is already improved over using the Soft Float.

I get 100% load and bad decoding when I use mbelib. No Surprise.

When I use the NW Digital Radio ThumbDV instead, the load drops down to around 50%. Decoding improves, but is not totally clear. The problem is overruns on the audio input. Using /dev/dsp1 for input and /dev/audio for output improves things slightly, but the input overruns are still noticeable every second. Disabling the input filtering ( -l ) improves things to almost perfect, but there are still some input overruns.

So some more work is needed to improve the code.

73 Eric

You're a few weeks ahead of me...thank you for saving me several hours, however a Pi solution must be on the horizon...somewhere.

 

[clemfm]

There is a new C++ rewrite of dsd, the digital speech decoder, that can decode P25, DMR, D-Star etc. It's called dsdcc ( https://github.com/f4exb/dsdcc ) It also supports doing the decoding with a AMBE hardware dongle.

So I thought I'd try this again with a Raspberry Pi 2... but I run into endless problems with dsdcc and its output to the pi sound. I either get Cannot open plughw:0,0 or when I preceed with with sudo, Error writing to output and I get the same when I try /dev/audio.

I am sure it's something dumb on my part. Getting sound to work with Linux is a big headache now days.

I was about to try this also when time permits. Linux sound, in most distros, is indeed a headache.

I'm trying an ODroid 2, and simply cannot get Ubuntu to recognize a USB card as device 0 (for /dev/pcm)... more on my ODroid challenges in another thread later.

 

[kb9mwr]

Has anyone made any headway using DSD on a Raspberry Pi 3 with a RTL-SDR to listen to DMR? Or is there some other software that can do the same?

I switched gears a while back and I have been using op25 to listen to the local public safety on Pi and that has been great. Looking to listen to a DMR system. Looks like there might be the start of DMR support to op25, but I am not sure what the plans are there.

 

[kb9mwr]

When I wrote that PDF just under a year ago, those tests were with a Raspberry Pi 2, and it maxed the CPU. I just tried it on a Raspberry Pi3, it still maxes out the CPU. The problem apparently is mbelib, its a single thread application. So I need to find someone capable of updating that, begging if necessary.

DC7DS says he uses dsdcc, and it runs quite well on an Odroid xu4. But honestly I'd rather put that money into some programmers pocket caring to tackle the underlying issue. Feel free to contact me off list if you happen to have that experience.