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AWR1642: What's the difference between rangeFFT and rangeProfile?

lin duan
Prodigy 155 points
Part Number: AWR1642

I got the data of range FFT and plot the data per antenna like the graph "range FFT" below:

the mean value of the antenna  plotted like "Range profile array (mean by frame)"

compare the level of "Range profile array (mean by frame)"  and "range profile form Uart", the whole shape of the graph is similar but the delta of max and min value is so different.

I have read the reference in file:///C:/ti/mmwave_sdk_01_01_00_02/packages/ti/demo/xwr16xx/mmw/docs/doxygen/html/index.html and know the rangeFFT is 1D-FFT,

rangeProfile is the 0doppler array of 2D-FFT. But i think it should be same value of (peakvalue - noisefloor), anyone can tell me why it is so difference?

or give me a formula to calculate the rangeProfile from 1D-FFT?

Thanks!

  • 0
    Prodigy 155 points
    i forgot to explain that the value i used in each graph had been recalculate by 20*log10(Uart value)
  • 0 in reply to lin duan
    TI__Guru*** 149044 points
    Hi,

    The range profile is computed in the following file

    C:\ti\mmwave_sdk_01_01_00_02\packages\ti\demo\xwr16xx\mmw\dss\dss_data_path.c

    This should help understand how the range profile is computed

    Thank you
    Cesar
  • 0 in reply to Cesar
    Prodigy 150 points

    Why are there diffrence between amplitude value of 1D-FFT and amplitude value of 2D-FFT in 0 doppler ??

    Both data is obtained from UART port. It will be same value, right ??.

    We guess one of the reason is from window function when calculate 2D-FFT.

     

  • 0 in reply to Cesar
    Prodigy 155 points
    Cesar,
    Thank you for you reply.
    I'm so sorry I tried to read it but I don't know C.
    Could you give me anyother simple explain about the diffrence between amplitude value of 1D-FFT and amplitude value of 2D-FFT in 0 dopple.

    Thanks!
  • 0 in reply to lin duan
    TI__Mastermind 21025 points
    Hi lin,

    It seems that you're asking about algorithmic issues of the 1D and 2D FFT processing. The Doxygen documentation provides a description of the processing steps, and the code provides the lower level of detail. It is possible that the difference is simply a matter of scaling, as the demo strives to be computationally efficient over algorithmically intuitive. To find the cause of the difference you are looking for will require digging into the code, possibly setting breakpoints and looking at various values at each step.