Re: Airspy Mini Direwolf APRS IGate RPi
Hmm.. I would think AF gain would be the simplest item to correct. I would keep digging as I'm sure that will be fixable. Btw.. are you using PulseAudio on your system? If so, consider looking at your pavucontrol mixer settings as well.
airspy_rx is a different animal as it's more of a real command-line SDR than a purpose built narrow-FM demodulator application. There are multiple ways to use it such as this CSDR example:
I was able to get that approach working with an AirSpy R2 but it took some adaptation as my system didn't support the specific destination audio codec. Even while working, the audio wasn't smooth enough for suitable APRS support:
$ airspy_rx -t 0 -r /dev/stdout -a 2500000 -f 144.390 -g 18 | csdr fir_decimate_cc 60 0.005 HAMMING | csdr bandpass_fir_fft_cc 0 0.1 0.05 | csdr realpart_cf | csdr agc_ff | csdr limit_ff | csdr fractional_decimator_ff 1.0416 | csdr convert_f_u8 | aplay -c 1 -f U8 -r 48000
It sounds like rx_fm might be a better solution for your targeted narrow-FM application as it's reported the overall CPU load might be lower with this approach.