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IWR1443: Question for IWR1443

Annie Liu
Genius 10295 points
Part Number: IWR1443

Hi Team,

The customer reads the bandpass filtered code portion of the CCS for detecting the heartbeat and respiratory signals. He found that the code has the parameters of pScaleValsHeart and pScaleValsBreath. Customer would like to know:

  1. What effect do these two parameters have on the bandpass filtering of the respiratory and heartbeat signals?
  2. The CCS code is transferred to matlab for band-pass filtering analysis, and it is found that the frequency spectrum in the filtered frequency band is shifted from the frequency spectrum in the same frequency band. Is this due to the above two parameters?
  3. What is the essential difference between the two parameters of the code and the absence of these two parameters?

Thanks.

Annie

  • 0
    TI__Mastermind 30405 points

    Hi Annie,

    Please allow me sometime to look into these questions. I will get back to you within the next couple of days.

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    TI__Mastermind 30405 points

    Hi Annie,

    Thanks for your patience. Here's the explanation:

    The demo implements a band-pass filter in software to separate the breathing and heart rate wave forms. The band pass filter is designed as an "IIR Bi-quad cascade filter" using Matlab function fdesign.bandpass (note that the DSP System Toolbox is required in Matlab). The structure of the filter is shown below:

    The Matlab filter design function returns the filter coefficients as well as the scaling factors (pScaleValsHeart and pScalValsBreath) which are required for the filter to work effectively.

    Regards

    -Nitin