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IWR6843ISK-ODS: Chirp Amplitude Falls Off With Time

Part Number: IWR6843ISK-ODS

Hello,

Everyone, I am working on a project using the TI mmWave IWR6843ISK-ODS. For my application I am also using a mmWaveBoostIC board and the DCA1000 for data capture. I was running a simple test of the radar by measuring a stationary scene. Throughout the entire measurement that is no change in the scene. Despite this when I look at the measured ADC data for all the chirps taken during the measurement their amplitude seems to significantly taper off with time (see image below).

To my understanding there should not be this large of a variance in the measured data vs time and I wonder if there are any explanations as to why this could be happening. Another important note is that when I take the FFT I see peaks in the image where objects are expected so the data is at least somewhat correct.

Thank You,

Cole Harlow

  • Hello.

    The most likely reason for this issue is that since the device is running for some time, the device is heating up and resulting in the degradation of the signal, and thus reducing the amplitude.  This can be adjusted in mmWave studio in the TxRxGainTemp tab.

    Sincerely,

    Santosh

  • Hi Santosh,

    Thanks for the answer, just to clarify the data above is for a single chirp. The chirp only lasts for around 125us. Is it possible that in such a short time the radar's temperature would increase enough to impact the signal so significantly?

    Thank You,
    Cole

  • Hello Cole.

    If the device has been plugged in for a while, it will heat up and so even if it is a single measurement, it depends on the state of the device with respect to its temperature.  You can try this measurement again after unplugging the device and letting it cool down, as well as using that tab in mmWave studio I mentioned in my previous response to account for this temperature change.

    Hope this helps,

    Santosh