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AWR1642: Confirm the BPM configuration corresponding to postproc

rongjiang liu
Expert 1275 points
Part Number: AWR1642

                                                                             fig1 Configuration

fig2 Result when Config 1/2

fig3 Result when Config 2/2

I am trying to cnfig 1 BMP frame,see fig1.

my frame is Chirp0_Chirp1_Chirp0_Chirp1_.....（128 cycles）, and phase settings by BMP config are:

Chirp0：TX0=0°，TX1=0°

Chirp1：TX0=0°，TX1=180°

Chirp0 and Chirp1 are all TX0 and TX1 EN=1.

Now i capture a adc data and postproc it. Results can be seen in fig2 and fig3.

first i cannot see the BMP config information in the programmed parameters at the right side of postproc window. Where is the BMP information? how can i confirm the config is right?

second how can i observe the difference between 0° and 180° in the plot？

  • 0
    TI__Expert 7215 points
    Hi,

    In the post processing plot drop down menu, You can select "Phase Stability across chirps" for BPM information.

    Also look at below e2e thread for more information.
    e2e.ti.com/.../2621651

    Regards,
    Kaushal
  • 0 in reply to Kaushal Kukkar
    Expert 1275 points

    fig4 Result when Config 1/2

    fig5 Result when Config 2/2

    Thanks Kaushal. your reply helps me , and further problems need to be solved. i post the "Phase stability across Chirps" plot for 4 chans.

    i know i need to compare the phase difference between config 1/2 and config 2/2 at the same chan, not  compare the phase difference between adjacent chans at the same config. 

    1/  i tried only 1 TX enable ,for the same chan, it is indeed 180° phase difference.

       you see fig4 and fig5. the phase difference between config 1/2 and config 2/2 at the chan1 is 31.5-(-53.5)=85°, not 180°.

       Here phase difference is not 180°, is it because two TXs may overlying each other, and T-R path difference intuoduces  additional phase, and  antenna spacing between TXs also  intuoduces  additional phase, right?

    2/ ideal space between 2 TX antenna is 1/2  wavelength, it should be 180° phase difference. But it is not 180° difference between adjacent chans in fig 4/5.

    it is also because the reason in question1?

    3/ If i set Calibr LUT Update like fig1 (that is Retain TxCauLUT=0, and Retain rxCauLUT=0 ), Need i calibrate the pahse difference?

     

  • 0 in reply to rongjiang liu
    TI__Expert 7215 points
    Hi Liu,

    You understanding on 1/ is correct.

    for 2/
    As you mentioned in 1, phase difference for same channel would depend on the path traveled which is

    d(TX1>Obj) - d(TX2->Object)

    and hence it is not 180deg. Also there would be additional phase due to antenna path mismatch etc.

    3/ TxCalLut and rxCalLut can't be use to calibrate phase difference.

    Phase can be calibrated by putting a strong object at fixed distance(zero angle) and measuring the phase for each RX channel.

    Regards,
    Kaushal
  • 0 in reply to Kaushal Kukkar
    Expert 1275 points

    I understand. Thanks very much!