A simple SDR QO-100 Ground Station (Part 3: Software Setup)

Virtual audio devices setup

Although it is possible to stream audio from/to Raspberry Pi's audio port, I wanted to separate the QO-100 audio from all the other "normal" audio in order to avoid inadvertently transmitting system system notifications or such like. 

Nowadays, for every popular OS there is a "virtual sound card" kind of software (such as Virtual Audio Cable for Windows or Loopback on macOS).

For Linux, no additional software is required (other than PulseAudio, which in Raspberry Pi OS comes installed as a default) and this is a simple matter of loading the right modules in PulseAudio.

Add the following to your /etc/pulse/default.pa:

load-module module-null-sink sink_name=qo-100-tx
load-module module-null-sink sink_name=qo-100-rx

And restart pulseaudio:

$ sudo killall pulseaudio

Because GNU Radio supports only ALSA devices, you will also need to create the ~/.asoundrc file with the following content:

pcm.qo-100-rx {
    type pulse
    device qo-100-rx
}

ctl.qo-100-rx {
    type pulse
    device qo-100-rx
}

pcm.qo-100-tx-monitor {
    type pulse
    device qo-100-tx.monitor
}

ctl.qo-100-tx-monitor {
    type pulse
    device qo-100-tx.monitor
}

Audio streaming

TODO

CPU overclocking

TODO

Disable WiFi

TODO

GNU Radio installation

TODO

Continue reading in Part 4 >>