How calc two dw3220 pdoa


I want to calculate two dw3220’s phase difference, Sub-register 0x0C:1E – Phase difference of arrival result, I can get the pdoa the same chip two anntena, but how to get pdoa on the different chip ?

when PDOA mode3, I can get Sub-register 0x0C:08 STS_POA and Sub-register 0x0C:10 STS1_POA, but the STS_POA - STS1_POA isn’t equal Sub-register 0x0C:1E PDOA, so when PDOA mode3, what is the phase relationship between STS and STS1 ?