You didn't specify whether you're just seeing "aU" in the terminal, or
if you're having audio playback issues. I'm going to assume it's the later.
This will help with the audio playback
create this file if it does not exist, otherwise edit the file:
~/.gnuradio/config.conf
Add this section to the file if your configuration uses ALSA. It's Ubuntu, it
probably does...
[audio_alsa]
period_time = 0.100
nperiods = 5
I don't know what the hell is up with the OP25 repository/wiki. This place seems just
as dead...
There are a few forks on github:
mmhhpp/op25
https://github.com/mmhhpp/op25
balint256/op25
https://github.com/balint256/op25
bitmunch/op25
https://github.com/bitmunch/op25 << this has a performance update
thanks to Luke, and a few other minor tweaks and stuff