Post a Comment On: Advancing Ham Radio.. different ideas

If you are a Ham Radio Operator you've probably been looking at the Raspberry Pi with a lot of possibilities.

One of it's downfalls if the lack of an on-board input.  But once you add a USB sound fob, Echolink, remote rig applications, IRLP, and decoding various digital modes like PSK, and so on, are all a reality.


Finding a USB sound device and setting it up can be aggravating.

I recommend the SYBA SD-CM-UAUD USB CM119 audio adapter.

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If lsusb doesn't report it as below, you have the wrong one:

root@pi:~# lsusb 
Bus 001 Device 005: ID 0d8c:000e C-Media Electronics, Inc. Audio Adapter (Planet UP-100, Genius G-Talk) 

Next you need to make the usb sound card (0) the default audio device
Check yours like so: cat /proc/asound/modules
0 snd_bcm2835
1 snd_usb_audio

Edit /etc/modprobe.d/alsa-base.conf comment out "options snd-usb-audio index=-2"
You want ""options snd-usb-audio index=0"

After a reboot it should always appear in this order:
0 snd_usb_audio
1 snd_bcm2835

Take this one step further and comment out the kernel module for the onboard sound and add the usb

cat /etc/modules should look like:
#snd-bcm2835
snd-usb-audio
While, I did not find the following necessary in my case, I have read to get better latencies out of USB audio devices, it is suggested to also add:

options snd-usb-audio nrpacks=1 Setup /etc/asound.conf to this:


pcm.dmixer {     type dmix     ipc_key 1024     slave {       pcm "hw:0,0"       period_time 0       period_size 1024       buffer_size 8192     rate 48000     }     bindings {       0 0       1 1     }   }   pcm.asymed {       type asym       playback.pcm "dmixer"       capture.pcm "hw:0,0"   }   pcm.dsp0 {     type plug     slave.pcm "asymed"   }   pcm.!default {       type plug       slave.pcm "asymed"   }   pcm.default {     type plug     slave.pcm "asymed"   }   ctl.mixer0 {     type hw     card 0   } 

Since there are some USB issues, I suggest setting the device to boot the USB hub in  USB 1.0 mode, this should fix choppy audio. (I did not find this necessary in my case, but it's not a bad idea)
Add "dwc_otg.speed=1" to /boot/cmdline.txt.

Pulseaudio might be part of your raspberry wheezy default image.  Personally I am not a fan of it, and have read it wasn't working well on the Pi.  I am not sure if that still holds true.  I just removed it:
apt-get purge pulseaudio
I recommend replacing it with Alsa.  It has been around a bit longer:
apt-get install  sox alsa-oss alsa-utils alsa-tools  

Also, I suggest updating the firmware on your Pi.
https://github.com/Hexxeh/rpi-update/


This should be a good starting point for most.  Hopefully in the future, newer Raspberry wheezy images can make this a bit easier, and more kernel support for other USB sound FOBs.

For my fellow hams you may want to check out these places to congregate:
https://groups.io/g/RaspberryPi-4-HamRadio/

http://amateurradiopi.com/forum/

And for those of you still interested in D-Star:
http://groups.yahoo.com/group/RaspberryPi-DVAP/ 

I have been running my Pi using a 5 volt, 1 amp supply via the micro USB power port.  I do not use a USB hub.  My model B rev 2 has been running reliably for a few weeks now.

Just as a note.  If you are making connections to the GPIO for keying a radio or whatever, check your local Radio Shack for "Schmartboard Jumpers ."  These are a new thing they are carrying, and are handy.