2021-04-26 02:27 AM
Trying to build a 433 MHz sniffer based on SDK example "SDK_Sniff_B.c". Im sniffing messages from TPMS sensor and get them on my PC with RTL-SDR. In the message parsed on PC I can read ID of sensor which goes right after sync word. With the help of URH I got signal parameters: frequency, datarate, deviation. I managed to get the message on my S2-LP, but I always find extra bits in this message. For example if I received 0x5955955A which is 0b01011001_01010101_10010101_01011010 this is manchester encoded sensor ID. On S2-LP I get 0x595ACAAD which is 0b01011001_01011010_11001010_10101101. Everything right except one extra bit. And further I find some more wrong bits in the message.
If I change physical parameters I get garbage in the message.
How can I get rid of this extra bits? How can I debug this?
2021-06-02 08:07 AM
If it helps someone:
We found out this behaviour is caused by Symbol timing recovery option turned off. Adding DLL algorithm according to section 5.5.3 of S2-LP datasheet sovled the issue