Hello, using 2x DW3000 for radar is a bit tricky.
To get better results, you can for instance increase the preamble length to 1024 symbols, and get the CIR from the ipatov preamble. For a first sample, no real need to use STS.
As a side note, we just released a new kit based on a new chip which provides pretty good radar results out of the box.
The SW release is already out (here: QM35 SDK 3.0 is now available - #4) and the HW kit should be available very soon.