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AWR1642BOOST-ODS: Questions about the demo of vital signs

Gilmmer
Intellectual 330 points
Part Number: AWR1642BOOST-ODS

Hi,

I am learning the demo of Vital Signs(mmwave_automotive_toolbox_2_4_3__win), and i have these following questions: 

1.There are two FFT processing, how many points FFT do they calculate separately? (). 

 I think both of these are calculate 1024 points,right? Only sampling 100 points, why not calculate 128 points but calculate the FFT of 1024 or other values?

2.Why the indexNumPeaks less than 4? （dss_data_path.c 1742 line）

3..What is the difference between heartRateEst_FFT and heartRateEst_FFT_4Hz？

4. What the meaning of freqIncrement_Hz ?（dss_data_path.c 2095 line）

5.How to calculate the length of range_bin? On the conditions of this picture, how long is this range_bin ?

Thank you very much!

  • 0
    Intellectual 330 points
    I am very sorry , i have choose a wrong Part Number. Actually, my Part Number is AWR1642-BOOST
  • 0 in reply to Gilmmer
    TI__Guru*** 149044 points
    Hi

    The vital signs processing includes 3 FFTs:

    First FFT is the range FFT. The second and third ffts are used to identify the breathing and heart rate.

    The first FFT is 128 points, the second and third FFTs are 1024 points

    indexNumPeaks is used to identify the peak in heart rate and breathing rate spectrums. The maximum was arbitrarily set to 4. We don't want to select only one peak because it may be produced by one of the harmonics and we may miss the peak produced by the heart or breathing rates.

    "heartRateEst_FFT" is the FFT computed between 0.9Hz (48beats/min) and 2Hz (120 beats/min) This is where we expect the main peak for the heart rate to be. However, it is possible that we get some harmonics from the breathing rate in this spectrum and the correct peak is not selected.
    Therefore, we also perform and FFT between 2Hz and 4Hz. This is the "heartRateEst_FFT_4Hz". If we detect a strong peak in this spectrum we know it must be the first harmonic from the heart rate and we will use this information to determine the heart rate.


    "freqIncrement_Hz" is the defined in the code "obj->freqIncrement_Hz = obj->samplingFreq_Hz / PHASE_FFT_SIZE;"

    range_bin - Please use the chirp configuration to compute the Rmax. Then range_bin = Rmax/#Range FFT points.

    Thank you
    Cesar