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IWR6843AOPEVM: Spurs target in the range-doppler map

Ugo Bertacchini
Intellectual 300 points
Part Number: IWR6843AOPEVM

Hi,

I am testing two IWR6843AOPEVM.

Both of them belong to lot 0315202102 (hw revision F).

The two serial numbers are: 1021910458, 1021910522.

With one AOP module I have a strange but repeatable noise behaviour: the range-doppler map of an empty area (looking to the sky) have two peaks at a fixed distance and speed. Some times the peaks are not focalized in the doppler domain (even if they are still present at the range bin). See the following image where 11 acquisitions in the same condition have been collected.

With the other AOP module in the very same condition the result is fine. See the following image.

The sensor with spurs is probably unaccettable from a signal point of view.

Is it a normal behaviour or there is something bad on that specific sensor?

Do you have any suggestion to reduce this kind of noise?

Best regards,

Ugo 

  • 0
    TI__Mastermind 23725 points

    Hello

    Would you please start out with the device Errata to identify the known set of spurs and how they correspond to your observations.

    IWR6843AOP Silicon Errata, Silicon Revisions 1.0, 2.0 (Rev. -)

    Thank you,

    Vaibhav

  • 0 in reply to Vaibhav Mahimkar
    Intellectual 300 points

    Hello Vaibhav, thanks for your feedback.

    The document was very useful to understand the possible cause of the spurs.

    ANA#14 seems to be the one that could cause our spurs.

    By the way there are two things not clear to me:
    1. Why the two devices shown such an high variation since we are using the same chirp configuration? Is it possible that same samples are not affected by the spurs? (please consider that both sensors are from the same lot)

    2. We are using roughly 1.7 GHz of bandwidth with starting frequency at 60.6 GHz and slope 40 MHz/us. As a workarounds TI suggest to avoid narrow bandwidth. I do not think 1.7GHz can be considered narrow but we cross 4 different critical frequency. What frequency span do you suggest (in terms of start frequency and bandwidth) in order to reduce this phenomena?

    Since we think those spurs can be a show stoppe for us, do you think it will be available a revision of the chip that will solve this issue?


    Thanks for you support!

    Ugo

  • 0 in reply to Ugo Bertacchini
    TI__Mastermind 23725 points

    Hello,

    For #1 more data set for analysis would help.

    For #2 You may want to consider chirp sets which will allow you to separate out spur related do real scene vs known -expected spurs.

    Thank you,

    Vaibhav