Raspberry Pi and dttsp
I think this could be of some interest for this list, this info comes from dttsp-linux group.
De : firstname.lastname@example.org [mailto:email@example.com] De la part de Glen Overby
Envoyé : dimanche 21 avril 2013 18:38
À : firstname.lastname@example.org
Objet : [dttsp-linux] sdr-core on Raspberry Pi
I bought a Raspberry Pi, and tried it out as an SDR. I'm now listening to WWV using my Softrock 6.3, E-Mu 0204 USB audio adapter, and R-Pi. I must mention that the 0204 is the largest of the components, and its about the size of the other two (but those are bare boards).
It was a an adventure getting here. The jackd that comes with the raspian distribution has problems (it coredumps). I found this page that has an explanation and fixes: http://wiki.linuxaudio.org/wiki/raspberrypi
I've found it to be very fragile. Plugging in a USB hub, or the 0204 caused it to crash (I didn't have a monitor connected at the time so I don't know the cause). If jackd fails to start once, it won't start properly again (removing /run/shm/* might be a fix to this). Jackd has to be started using the hardware index from /proc/asound/cards, not the name.
I ran jackd at 48khz. I overclocked my R-Pi to 900mhz, and observed sdr-core with top:
28% cpu in ssb mode
40% after setNR 1
40% after setANF 1
32% after setNB 1
55% with all 3 turned on
When I turn on filter and meter (-s and -m), the cpu utilization goes up about 2% (but that's without anything retrieving spectrum or meter). jackd runs at about 5.5% cpu.
I installed these additional packages in order to build:
- dttsp -
- usbsoftrock -
(I hacked out the interactive mode; it needs ncurses)
without a GUI, I had to configure dttsp manually. For those who haven't done this before, here's what I did:
nc -u localhost 19001
setFilter 50 2500
then I tuned with usbsoftrock 12000 hz lower than the desired frequency, e.g. for WWV at 10mhz:
usbsoftrock set freq 9.988
I haven't tried to transmit yet.