When doing DS-TWR ranging in good radio conditions where distance or any radio obstacles should not be issues, I still get SFD timeout errors (RXSFDTO flag in the status register) every now and then. The error happens when the DS-TWR responder is trying to receive the poll message from the DS-TWR initiator. This happens less than once in every 1000 measurements, but still quite regularly.
The error happens with 110k bit rate (Ch 5, PRF 64MHz, PLEN 1024, PAC 32). If I change the bit rate to 850k (PLEN 512, PAC 16) the error is much less frequent (less than once in a million measurements).
Having 0.1% of measurements fail is not catastrophic, but I was still wondering if someone would know what could be causing that, or is it just normal RX noise and to be expected to happen at this rate? The SFD timeout settings are correct and I have tested with “too long” timeouts (so there is no real timeout due to SFD not being present, but instead a failure to detect the SFD when it is there).
There is nothing exotic in the DS-TWR implementation and it is essentially similar to the Decawave example. This also happens when using two Trek devices as initiators and responders, so it is not a HW issue related to our hardware specifically.