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JTam.1
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May 6, 2021
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Can the time domain output of FFT calculation from MotionSP be speed (mm/s RMS), not acceleration on Y-axis?

  • May 6, 2021
  • 1 reply
  • 676 views

Hi, Can the time domain output of FFT calculation from MotionSP be speed (mm/s RMS), not acceleration on Y-axis? Please advise. Thanks!

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    Best answer by niccolò

    Hi @JTam.1​ ,

    in the sTimeDomainData_t structure variables you have the speed variable in the time domain data, but it is derived from the FFT circular buffer.

    if you try to use that to compute the FFT you will have a delayed output withan error due to approximation and calculation error and noise error propagation.

    the best way should be to develop an integration algorithm and then compute the FFT with another library, but even in this case, it is not advised to use the acceleration integration as the core of your computation.

    hope this helps

    Niccolò

    1 reply

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    niccolòAnswer
    ST Employee
    May 6, 2021

    Hi @JTam.1​ ,

    in the sTimeDomainData_t structure variables you have the speed variable in the time domain data, but it is derived from the FFT circular buffer.

    if you try to use that to compute the FFT you will have a delayed output withan error due to approximation and calculation error and noise error propagation.

    the best way should be to develop an integration algorithm and then compute the FFT with another library, but even in this case, it is not advised to use the acceleration integration as the core of your computation.

    hope this helps

    Niccolò

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