I am out of my depth here What they are beaming at the moon are not mechanical sound waves (which obviously won't cross the vacuum that separates earth and moo

I am out of my depth here What they are beaming at the moon are not mechanical sound waves (which obviously won't cross the vacuum that separates earth and moon) but radio waves (= electro magnetic radiation) Since we are talking about audio waves at both input and output of the demonstration ...there is presumably a conversion of audio waves to radio waves -- possibly using some form of modulation like AM or FM to encode the audio information. Assuming it is FM modulated, given that the return signal has all kinds of doppler effects due to relative velocities ... we can't simply tune into the base frequency of the FM Modulation carrier wave ... but need to correct it with each passing minute maybe. And the frequency modulation encoded on top of the carrier wave should also be scaled back proportionally based on doppler correction. Once we do that though...why wouldn't the echo sound identical to the origibal? I didn't quite follow why there is still a change in pitch of the audio between input and output. Did they simply skip the second step of error correction described above and are showing the resulting distortion in recovered audio after FM demodulation?