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IWR6843ISK: How do radar parameters affect phase sensitivity?

Felipe Parralejo
Prodigy 30 points
Part Number: IWR6843ISK


Tool/software:

Hello,

I'm using the IWR6843ISK to measure heart rate using the phase difference between consecutive frames. I've been using this device for quite a long time, but I still don't understand how chirp parameters affect the measured vital signs. I have noticed that choosing the wrong parameters heavily affects the readings, hiding the signal and making it impossible to recover, but I don't know how to tune my parameters in the right direction. Basically, I would like to have greater phase sensitivity, to be able to measure slight changes in phase. Is there any guide to parameter setting?

Thanks in advance!

Best

  • 0
    TI__Genius 12220 points

    Hi

    For Vital signs signal chain, chirp timing is very closely coupled and changing the chirp configuration will affect the functionality. Breath rate is filtered from 0.1-0.3 Hz, while heart rate will be filtered from 0.8-2Hz. Changing the frame timing will affect sampling rate of the inputs at the vital signs chain. Also, filters are so designed that any change in the fft of the phase difference will not be adaptively filtered. So, it is not possible to change the chirp configuration in Vital signs demo

    Entire chain will have to be reworked if the configuration is changed

    Regards

  • 0 in reply to Abhishek Karkisaval
    Prodigy 30 points

    Hi,

    Thank you for your interest. I know how the chain is designed, but I am not using the vital signs demo as I did not get it to work and I work in research. I am doing the processing myself using the data obtained from the out of box demo. My question is directed towards the individual chirp parameters (slope, times and so on) instead of frame periodicity, which is clear to me as a parameter, however the rest are not.

    Best

  • 0 in reply to Felipe Parralejo
    TI__Genius 12220 points

    Hi,

    The Vitals signs chain picks only one input from each frame. So, only the frame periodicity affects the phase differences for Vitals computation

    Chirp parameters like slope, chirping time, chirp periodicity affect the range and velocity for tracking a person. The locations of the tracking person is sent as input to the Vitals chain. You can refer to TI sensing estimator to understand the variations of chirp in detecting objects

    https://dev.ti.com/gallery/view/mmwave/mmWaveSensingEstimator/ver/2.4.0/

    You can change the chirping parameters and see the change in detetcion

    Regards