I have been experimenting with demodulating the “funny pattern” from TRANSIT 5B-5 using USB mode. I was expecting some sort of slow, multi-tone FSK and indeed it appears to be so.
I like the sound of TRANSIT 5B-5, it sounds so antiquated,
no wonder, it was launched 1964 and probably it is
the oldest, transmitting satellite in space.
I wonder if the signals are nonsense or decodable data?
Maybe telemetry.
I also thought it was telemetry but it seems to be repeating the same pattern. So I am wondering whether it is just some frequency pattern used as signal source for some measurements.
I plugged it into sound visualiser and it shows a regular 1216Hz tone that seems to be a marker of some description and the majority along a 870Hz carrier (or some term like that). I’ve not used this software before but it makes it easy to see whats going on.
Well, according to that link the signal is telemetry. Note that the actual audio frequency in my audio recording is arbitrary, as I am using USB demodulation and just tune to have the tones within the audio passband. As we can see in the IF spectrum, there are more sidebands to consider.