Acoustic FSK modem

audio idle

Send

pick a file
idle

Both laptops must use the same preset. Start the receiver first. Speaker at 40 to 60 % volume, half a metre apart, robust preset for the first try.

Receive

mic off
SNR, dB
tone balance, dB
sync correlation
0 / 0frames ok / seen
bits fixed, last frame
0audio drops
waiting for a START frame