My assumption would be it has some form of dynamic frequency selection algorithm so it sits there and listens for a bit to find an employee channel and uses it for broadcast.
How do WSPR signals avoid frequency collisions?
Submitted 1 month ago by einfach_orangensaft@sh.itjust.works to amateur_radio@lemmy.radio
yo3gnd@lemmy.radio 5 weeks ago
They don’t.
You randomly position yourself somewhere in the tiny sliver of a sub-band, and TX. An important bit of WSPR operation is to only transmit in 10-20% of the windows, not all of them. I guess it is a form of poor man’s TDMA.
Another trick, also used by FT8 SWL mode: you decode a batch of signals, you regenerate their audio and subtract that from your RXed audio. This is called a pass. Repeat for a few passes, decode after each.
Hidden signals discovered like this are not perfect and rely heavily on FEC, especially if something else masks them, but hey do show up.
einfach_orangensaft@sh.itjust.works 5 weeks ago
Thx for the answer, also very interesting, never heard about that FT8 audio subtraction method before but makes total sense :D