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IWR1443BOOST: FutureChange_in_vitalSign_FrequencyBand

ZHENGGUO SUN
Intellectual 425 points
Part Number: IWR1443BOOST
Other Parts Discussed in Thread: IWR1443

Hello everyone,

What are your thoughts about implementing "Vital signs application" in 60GHz Frequency Band, considering the following plot that describes the relationship "Attenuation vs. Frequency" showing that at 60 GHz, the mmWave is the most susceptible to the atmospheric attenuation, particularly from the Oxygen in air. 

Please share your thoughts on your frequency of choice. Thank you so much,

Regards,

Zhengguo Sun

  • 0
    TI__Guru 50240 points
    Hi Zhengguo,

    The IWR1443 is for 77 to 81 GHz only. This would be the recommended band for use.

    60 GHz is also an acceptable band but this may depend on a particular application or regulations.


    Cheers,
    Akash
  • 0 in reply to Akash Gondalia
    Intellectual 425 points
    But to my limited knowledge, 77 ~ 81 GHz band isn't allowed in hospital application which means there has to be a frequency band change for the vital sign application.

    Also, don't you think 60G is a bad choice for any mmwave application given the attenuation described in the plot?

    Thank you,

    Zhengguo Sun
  • 0 in reply to ZHENGGUO SUN
    TI__Mastermind 28257 points
    Hi Zhengguo,

    The attenuation of 60 GHz waves by oxygen is 16 dB/km. That's 0.08 dB at 5 meters, which I would assume is the maximum distance one would need to sense the hospital patients heart rate from. (Note such a distance requires using a dielectric lens to focus the waves into a very narrow beam.) 0.08 dB would have a negligible effect on the heart rate sensing.

    Regards,
    François.
  • 0 in reply to Francois Charlot
    Intellectual 425 points
    very good explanation. thank you very much.
    I have one more question about the device operating at a LOWER frequency range, i.e. down from 77G range to 60G range. How would it affect the Receiver's sensitivity to very small change? because the wave length is longer at 60GHz, so based on the phase-displacement relationship, the same amount of phase variation will corresponds to a smaller displacement @ lower frequency, i.e. if at 77GHz, a d(phase)= 1pi corresponds to a d(distance) = 1mm, then @ 60GHz this relation would become d(phase) = 1pi --> d(distance)= ~0.8mm, which shows a less sensitive receiver response to the small displacement. It is clearly not helping in detecting the vitalsign via tracking small displacement. Is there any measure to make up for this performance loss resulted from operating the module at a much lower frequency?

    I'm very concerned about the performance change because we are focusing on the application of mmwave in vitalsign tracking, and we hope the module could track the displacement of chest movement at various angle. and this would require a very high sensitivity of Receiver to a minute change of chest movement because at an angle (rather than orthogonal,) the displacement seen by receiver would be only a fraction (one vector term) of the actual displacement (vector sum). And I'm already confirmed that in the future the operating frequency of the module for vital sign application will be designed to operating at 60GHz frequency band.

    Thank you so much.

    Zhengguo Sun
  • 0 in reply to ZHENGGUO SUN
    TI__Mastermind 28257 points

    Hi Zhengguo,,

    You are right a change in the center frequency from 79 to 60 GHz translates the wavelength by 30%, which would affect the measurement of small distance changes.

    We have measured the sensitivity of a 77 GHz radar to small changes by aiming a target that moves by small increments of 50 um. Over a number of measurements, we have seen a 3 sigma precision of 15 um. Unfortunately we did not publish this experiment (since then we have published the high accuracy range measurement lab [link]).

    Assuming a 1x impact of the wavelength increase on the precision, a 60 GHz sensor would have shown a 20 um precision in the same experiment. This is about 5x to 10x less than the chest displacement the heartbeats cause. So a 60 GHz sensor should be able to monitor the heart rate.

    The biggest challenge I see in measuring the heart rate from an angle is that little of the radar signal may come back to the radar RX antenna as radar waves behave like light waves. This would happen at any frequency.


    Regards,
    François.

  • 0 in reply to Francois Charlot
    Intellectual 425 points
    Thank you Francois. The information you provided is very helpful. Also is it possible to share the experiment documents? If not it's fine. I appreciate your help.

    regards,

    zhengguo Sun
  • 0 in reply to ZHENGGUO SUN
    TI__Mastermind 28257 points
    Hi Zhengguo,

    Unfortunately we will not publish this early experiment as it was not enough general purpose. I have pointed you above to the high accuracy range measurement lab which contains the firmware, a GUI and the documentation. That's your best and quickest way to make 1-dimensional precision measurements with our sensors.

    For the heart rate though, please be aware we will release in the coming weeks a firmware update with a new, more sensitive signal chain that is able to monitor the heart rate from the person's back. This was demonstrated at the CES 2018 earlier this month.


    Regards,
    François.
  • 0 in reply to Francois Charlot
    Intellectual 425 points
    that sounds so cool. Great news. would users be notified about the new firmware update when it is available for download? also, you've been mentioning heart rate monitoring, but as far as I know, the heart rate is just an estimation based on the chest displacement plot. Is there something that I misunderstood? sorry to keep bothering you. I do greatly appreciate your help.

    Regards,
    zhengguo sun
  • 0 in reply to ZHENGGUO SUN
    TI__Mastermind 28257 points

    Hi Zhengguo,

    I am not aware of an alert mechanism on dev.ti.com, so you have to monitor the mmWave Sensors folder there (link). I said heart rate monitoring, but indeed that's vital signs monitoring which includes respiration rate as well. The firmware user manual gives a bit of background on the signal processing chain we use. Indeed we start from the chest displacement information.

    Regards,
    François.

  • 0 in reply to Francois Charlot
    Intellectual 425 points
    thank you Francois. wish you all the best in 2018.

    Regards,

    Zhengguo Sun
  • 0 in reply to ZHENGGUO SUN
    TI__Mastermind 28257 points

    Thank you Zhengguo. I realize we have posted a video of our new vital signs monitoring firmware on Youtube.