Hi Please enable raw mode squelch. It does wonders when debuging remote loctions (ppm_error!). And significantly reduces data volumes. rtl_fm -R -f 1**M -s 12k -l 220 | sox -r 12k -t raw -e signed-integer -b 16 -c 2 -V1 - -C 0 out.flac sox out.flac out_s.wav silence -l 1 0.2 1% -1 2.0 1% SG