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AWR2944: Some spur in the Doppler

jian nie
Prodigy 20 points
Part Number: AWR2944

Hi,

    Use the 4TXs DDMA (0, 90, 202.5, 292.5),there are some spurs in Doppler map as follow picture. Calibrated the phase shifters.Can you give us some advices? Thanks.

  • 0
    TI__Mastermind 30715 points

    Hello,

    What is the frequency of the spurs? Does the amplitude of the spur change if you adjust the RX gain?

    Regards,

    Adrian

  • 0 in reply to aozer
    Prodigy 20 points

    Hi ,

         The frequecy  of spurs are  as same as the target frequency (the same Range Bins with target). The DDMA phase step are ok in 1DFFT. Today I will change  RX gain to check the spur amplitude.Thanks.

  • 0 in reply to aozer
    Prodigy 20 points

    Hi

         Change the RX gain ,the spurs amplitude wil change with RX gain linearliy. Thanks.

  • 0 in reply to jian nie
    TI__Guru* 91206 points

    Jian - 

    Thanks for the update that you were able to adjust gain as Adrian suggested to do and see a change in your return. 

  • 0 in reply to jian nie
    TI__Mastermind 30715 points

    Hello,

    Can you provide the details on the chirp configuration you are using? Is it also possible to share the details on your test setup?

    Lastly, if you use the test source do you still see the issue? This would help confirm that there is no post processing issue.

    Regards,

    Adrian

  • 0 in reply to Josh Wyatt
    Prodigy 20 points

    Hi，

          Adjust  the RX gain,  the amplitude difference between target signal and spurs are almost fixed。For example， decreaseing  3dB of the  RX gain  ，the amplitude of target signal and spurs signal will   decrease 3dB  a the same time。Thanks。

  • 0 in reply to aozer
    Prodigy 20 points

    Hi，

        The chirp configuration parameters are as  following pictures：ADC Fs is 25MHz, 512 sample points in a chirp; slope is 10MHz per uS; 512 chirps (16 chirps is a loop, 32 loops.) in a frame.  DDMA phase steps in last pictures.

  • 0 in reply to jian nie
    TI__Mastermind 30715 points

    Hello,

    Thanks for the details. I am checking with our systems team if they have any ideas and will get back to you. 

    In the mean time, can you confirm if this is custom hardware or the TI EVM?

    Regards,

    Adrian

  • 0 in reply to jian nie
    TI__Mastermind 30715 points

    Hello,

    I had some discussion on this issue with one of our algorithm experts. To help understand this better, he requested if you could try enabling only one transmitter (keep the same phase shifter settings for that transmitter) and see if the issue is still present. So, keep only TX4 with the 292.5*N phase shift and see if the issue is still present. Can you try this?

    Also, please help confirm the previous question on if this is being tested on the TI EVM or custom hardware.

    Regards,

    Adrian