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Spreading Factor 5

We are working on a research project with SX1262 chips. The set up is that we have multiple SX1262 chips transmitting and own SDR based receiver as a central control. While using this setup for SF 7 the things work fine and as desired but for SF 5 we are unable to decode the signals using own custom software. Can someone guide as to what changes to whitening sequence or interleaver for SF 5 needs to be done vis a vis SF 7 so as to carry out proper demodulation and decoding. Any literature on this??

I can’t speak to whitening, but this may be the same on SF7 as SF5 – I don’t know.

The main difference will be that symbols are 5 bits instead of 7 bits, so the gray coding will be on 5 bits and the interleaving will be on blocks of 5 bits * (4 + CR). There are articles about LoRa symbol grouping & interleaving, but not from Semtech. The internet has them.

Otherwise, you can poll registers 0x749:0x74A to get the raw symbol bits. This is unofficial information. I do not work for Semtech, and they will definitely not support you on this. But this is the best way to reverse engineer any LoRa encoding on the SX126x.