Regarding Observation 988930 … what’s up with the audio, I usually just receive static if that’s important.
You are hearing the digital signal from the satellite. (Bit like the tones from a fax machine, but from space!).
There will be odd shifts in the tone because of Doppler and perhaps the satellite health also moves things around a little.
The fun ones to listen to are voice and CW.
If I have misunderstood your question, just let us know.
The satnogs client records audio differently depending on the expected downlink. For example, if it expecting FM voice, you will either hear static or people talking. Same for SSTV and APRS (like NO-84, ISS digipeater, etc.). However if it expecting something like CW, it uses a very narrow filter right where the signal should be, so even if there WAS voice, you likely wouldn’t hear it. Same with static, just like when you put a ham transceiver into CW mode, the loud “static” noise goes mostly away and all you hear is a very low hollow sounding background.
In this case, I suspect that the BPSK1k2 decoder uses a narrow filter, and thus the audio isn’t as loud as other observations.