testing out CARLA's plugin host, using an alsa USB sound card directly,
on a Raspberry PI 4...also testing CARLA's experimental feature, 'ADD JACK APPLICATION' to include MUMBLE
and a RECRI KEYER CW AUDIO BANDPASS FILTER into the CARLA CONNECTION BAY
FLdigi is keying a 555 square wave oscillator and sending into the PI's usb sound card's LINE INPUT
from there the apps RE-GENERATE that harsh raspy square wave into a PURE SINE WAVE with shaped edges