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IWR6843ISK-ODS: snr of point cloud

Smart Fountain
Intellectual 320 points
Part Number: IWR6843ISK-ODS

HI,

Could you explain the meaning of "snr" in the Point Could array. How does it calculated ?

In our test, the snr of points which target index "254" and " 255" were almost same value of the normal target's points.

They are considered as outside of boundary or as noise, so they supposed to be small value, aren't they ?


The tested package is following.

ti\mmwave_industrial_toolbox_3_3_1\labs\lab0020_pplcount_Overhead\GUI_A_base_no_logic

Best Regard,

Fountain

  • 0
    TI__Mastermind 28055 points

    Hi Fountain,

    SNR is calculated during CFAR as the peak value of the detected point divided by the average value of the reference bins. (<PeakVal>/<CFAR Reference Value>)

    Points are labeled by GTrack to be 254 or 255, SNR is calculated in the signal chain before GTrack.  These points are points that are outside the boundary (which is a gtrack setting, so it does not effect SNR), or points inside the boundary that are not associated with a tracked object. This is also independent of SNR.

    Regards,

    Justin

  • 0 in reply to Justin Curewitz
    Intellectual 320 points
    Hi Justin,

    Thank you for your reply.

    I understood that label 254 and 255 are independent of SNR.

    I have 2 questions in your answer.

    1. Where is the data to obtain "the average value of the reference bins." ? Are "the reference bins" obtained from the result of 3rd FFT (angle FFT) ?
    2. Which bins are "the referenced bins" in all of the FFT bins ?

    Could you please suggest if there are any documents for reference to learn them.

    Best regards,

    Fountain
  • 0 in reply to Smart Fountain
    TI__Mastermind 28055 points

    Hi Fountain,

    1. The reference bins are the bins used during CFAR to determine if a point is detected.  Please see this short article on CFAR to understand the basic principle.
    2. We do range-doppler detection.  There is a 1D CFAR pass on the 1-D range FFT, then another 1D CFAR pass on the 2D doppler FFT (for each range bin with a detection)
      1. for the first pass, reference bins are the FFT bins around the bin under test.  These come from the Range FFT.
      2. For the second pass, reference bins are the FFT bins around the bin under test.  These come come the Doppler FFT.
    3. Our SNR is calculated with the Doppler FFT reference bins used as the noise floor value.

    Regards,

    Justin

  • 0 in reply to Justin Curewitz
    Intellectual 320 points
    Hi Justin,

    Thank you for your suggestion.

    I will read the article. If I have another question, I will post another thread.

    Regards,

    Fountain