Starting with a disclaimer, I don’t know, what follows is speculation only.
I suspect that the only requirement is that the slope of the chirp at encoding and decoding is the same.
Ultimately, it’s used to remove noise in relation to a reference level.
I haven’t had an opportunity to do the math to confirm this and I’ve bookmarked a few LoRa videos to see if they get into the mechanics, but I’m not holding my breath.
socsa@piefed.social 2 weeks ago
There is a preamble, which is a known sequence. The receiver uses the preamble to find the timing and frequency offset for the transmitter. In most LoRA-like systems, the modulation parameters are manually configured at runtime, though there is no reason why dynamic payload params cannot be specified in a header. That’s just a bunch of additional complexity these systems try to avoid most of the time.