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Original question:

AWR1843: Can numAdcSamples and numRangeBins be set independently?

IWR1443BOOST: Zero padding in FFT

katsuyuki kaneko
Prodigy 210 points
Part Number: IWR1443BOOST
Other Parts Discussed in Thread: AWR1843, IWR1443, , CCSTUDIO

Dear;

In the previous article of the forum, there's question whether we can configure numAdcSamples  and numRangeBins with different values in AWR1843.

I'd like to ask whether this is true in iwr1443 case.

I'm now investigating methods to improve accuracy of distance measurement and trying FFT with 'zero padding' e.g. 1024 point FFT by 256 points real data and 768 points zero-padding,

as this seems simpler way than zoom-FFT.

Thanks and regards,

Kaneko

  • 0
    TI__Guru 50240 points

    Hi Kaneko,

    Are you using the High Accuracy Range Measurement Lab or the standard Out of Box Demo on your IWR1443BOOST?

    I will have a response for you by end of the week.

    Regards,

    AG

  • 0 in reply to Akash Gondalia
    Prodigy 210 points

    Dear Akash-san;

    Thank you for quick reply.

    I'm now modifying 'high_accuracy_14xx_pjt', mainly to add pre- and post-processing.

    So far as I evaluated  the combination of conventional FFT and interpolation, I could not get enough resolution (around a few millimeter).

    So I'm now wondering which is better, zoom FFT or zero-padding FFT to get initial bin data, but programming HWA and EDMA is a little bit complicated for me.

    I appreciate your help.

    Thanks in advance,

    Kaneko

  • 0 in reply to katsuyuki kaneko
    TI__Guru 50240 points

    Hi Kaneko,

    The zoom-in FFT is likely to get you much better accuracy.

    Have you been able to download the High Accuracy Lab Source code in CCSTUDIO? Let me know if you have specific questions on this lab.

    Regards,

    AG

  • 0 in reply to Akash Gondalia
    Prodigy 210 points

    Dear Akash-san;

    Yes, I tried zoom-FFT in he High Accuracy Lab 14xx project and could get nice results with sub-mm precision.

    So, I appreciate your advice and I do not want any information about zero-padding FFT.

    As I will close this issue now, but I have one question about precision.

    I'm now evaluating zoom-FFT in the level-sensing environment and I found the deviation between measured value by zoom-FFT and real length

    vibrates or bounces periodically as the distance increase. The period is full or half of wave length of carrier frequency(80GHz) and its magnitude is

    around a few mm to 10 mm depending on the measurement condition. This result is also seen in the combination of conventional FFT and the interpolation technique on iwr1443boost.

    I'd like to ask you about similar experience or possible comment on this.

    Thanks in advance,

    Kaneko

  • 0 in reply to katsuyuki kaneko
    TI__Mastermind 23725 points

    Hello Kaneko,

    We are glad to hear that  zoom FFT has helped you get the desired accuracy. 

    Regarding your follow up question - we have not observed oscillations which are specific to algorithm.  Are there any physical vibrations in the system that you have to account for?

    For adjacent questions and its follow we recommend you to open a new e2e ticket. We will close out this thread based on original question's resolution.

    Thank you,

    Vaibhav

  • 0 in reply to Vaibhav Mahimkar
    Prodigy 210 points

    Dear Vaibhav-san;

    Ok, I'll close this thread and I will ask my question in the previous reply as a new thread.

    Thank you very much.

    Kaneko.