AoA IQ data seem NOT uncorrect, when used one antenna?

[upupsky]

software: ncs v1.8.0

hardware: my test nrf52833 board, with 9 antennas.

I do experiment like this:

aoa rx:  in "nrf52833dk_nrf52833.overlay" file, I set  "dfe-antenna-num = <2>;" and "dfe-pdu-antenna = <0x4>;"

             in "main.c" file, I set "const static uint8_t ant_patterns[] = {0x4, 0xB};"

this means, I use only 2 antennas(1 antenna 0x4 receive pdu and 8us ref period samples; 2 antenna 0xB receive 148us cte signal[will not switch to 1 antenna]), the 45 samples like this:

QUESTION:

    cte signal f=250KHz(T=4us), slot 4us.  after 1 antenna samples 8us, then switch to 2 antenna samples 142us(37 samples). the phase of the 37 samples  should  be permanent(because aoa tx tag not move all the time), the right picture, it seems cte signal is not 250KHz(4us){the cte almost T=4us*24=96us},  I wanted like this(red points):

where am i wrong?

thanks.

 

[upupsky]

you mean, the reference period 8u is used to calculate phase drift parameter, which is used to calbirate the 148us samples?

thks

[PaKa]

Not the way I would word it, the reference period is where you determine the base phase and the phase velocity (basically the frequency) and this is then used to predict the un-shifted phase for each of the data samples and then you can see the phase shift introduced by changing the antenna. You don't try to calibrate to any given frequency