I am using rfd900 radio for communication between my drone and system, Firstly on both sides I used rfd900 and was able to get the data correctly on the system. I was manually serializing and sending the data from transmitter side and reading it on Putty on the receiver side. Now I am using plutoSDR on the receiver side and to get the IQ data. I am running a MATLAB code that generates a CSV file which then I give input to URH and generate a binary data file, Now I am checking the binary file manually to verify Whether I am getting the data correctly, So yes there were Sik frames present in the binary file and was able to extract preamble, sync1, sync2, netID, length fields correctly but the payload of it contains different data then MAVLink. but the Sik payload contains an MAVLink packet. Does anyone have any idea of it? I am sharing a sample packet below that I extracted from the binary file
[0101010101010101010101, 2d, d4, ff f8, 10, 9a 10 8c 33 25 e4 7d d0 24 70 97 6f 08 5a c7 83, ff, ff ff]
[preamble(22 bits), Sync1(1 byte), Sync2(1 byte), NetID(2 bytes), Payload_length(1 byte), Payload, Trailer(1byte), CRC(2 Bytes)].
Very interesting!
I have tried something similar in the past with another SDR and got more or less the same result. My conclusion was that there are some data whitening being performed on the payload part. I haven’t pursued it further but it would be interesting to know if/when you solved it.
For interest I just picked the Si4030 transceiver, as I am not sure which transceiver is used in the EZR32 chip (used in the RFD900). In that datasheet they give more details about the data whitening and as you can see it only affects the payload section. Also explains why we can decode the preamble and sync words but not the payload:
Hi @copilot
Thanks for the information.
I looked at the documents of the transceiver chip and found about data whitening, did de-whitening using the pn9 sequence, and was able to get data fields correctly up to MAVLink msgID correctly, but it now got stuck at its payload.
Have any idea of it?