QRQ CW on the Raspberry Pi - demo of sending & receiving Morse Code tones over Mumble on iCW

[Chuck aa0hw]

This video demos a - low cpu use - software setup - for sending and receiving morse code over Mumble Voice Chat on iCW using only the single analogue audio output of the Raspberry Pi the bcm2835 alsa sound card(output only)

NOTE: Raspbian Debian Jessie is the OS for this RazPi2b

for the lowest CPU use and best performance, only ALSA and JACK AUDIO CONNECTION KIT were used.(Pulse audio increases the CPU usage higher than when using Jack/alsa)

APPS being used:
1. Mumble
2. FLdidi (fldigi does not have an id showing in Patchage)
http://www.w1hkj.com/
3. Jalv.select (for the stereo LV2 VU METER plugin)
https://github.com/brummer10/jalv_select
4. snd-aloop
http://www.alsa-project.org/main/inde...
5. alsa_in - alsa virtual audio cable for Mumble OUPUT
http://manpages.ubuntu.com/manpages/t...
6 alsa_out - alsa virtual audio cable for Mumble INPUT
http://manpages.ubuntu.com/manpages/t...
7. Patchage - Jack audio connection bay
https://drobilla.net/software/patchage

jack audio was set to 48k sample rate at 512 buffer frames
with QJACKCTL first
http://qjackctl.sourceforge.net/
....then Patchage will remember those settings and you should be able to just bring up Patchage the next time for jack to start with the sames jack settings initially set by qjackctl. Qjackctl does fine, but i prefer the way Patchage does things...

Mumble was in LOOPBACK SERVER TEST MODE for this demo, cw audio goes to the mumble input, then to the mumble server, and the server bounces that audio right back to the iCW station so you can hear your own signal... the audio you hear in this video is what the cw would sound like to everyone else that is connected to Mumble and listening...(mumble client located in Missouri, mumble server located in Texas)

Two alsa loopback cables were created using alsa_in and alsa_out commands in terminal. They show up inside the Patchage jack audio connection bay so you can draw wires from the Mumble output to the bcm2835 alsa sound card (called "system") and draw wires from the output of FLdigi over to the Mumble INput as shown in the video

the autostaic debian repository may be necessary to get the normal jack audio connection kit apps to work properly on the raspberry pi(s)
please see their website for more info :
http://wiki.linuxaudio.org/wiki/raspb...
https://www.raspberrypi.org/forums/vi...
t=37011&p=661006
http://rpi.autostatic.com/

for more info @ iCW see here:
https://sites.google.com/site/icwoip/

RE: ALSA LOOPBACKS DEMO'd in the VIDEO
for mumble output here is the command i used in terminal
alsa_in -d hw:5,0 -n5 -c1 -q0 -j Mumble_OUTput
for mumble input here is the command i used in terminal
alsa_out -d hw:4,0 -n5 -c1 -q0 -j Mumble_INput
in etc/modules i have this command so that 4 loopbacks are always ready to use
snd-aloop enable=1,1,1,1
NOTE: i think one of reasons the CPU is so low when using all this software, is that you can control the audio "quality" of the alsa loopback cables, by setting the "q" parameter in your terminal command structure to "zero" as shown just above...and as you can hear, it does not seem to lower the quality of the cw audio tones you hear...so the lower quality setting still sounds good and is less taxing on the CPU, by using the lowest quality setting(0-4) of these alsa loopbacks

NOTE: also, i think it is significant that everything is still performing well in spite of the recording software, simplescreenrecorder, really stressing the CPU