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IWR1642: mmW sensors liek IWR1642 for close proximity (2 cm) measurements?

Olaf Albert
Intellectual 320 points
Part Number: IWR1642

Hello,

Is there any chance (perhaps by a low power test mode) to get precise distance measurements with the very narrow distance of about 2 cm?

We would like to use the sensors in a production line checking the hights of metal or plastic objects (with a diameter of about 3 cm) with a speed of 20 objects per second.

Thank you for the answer!

Best regards,

Olaf

  • 0
    TI__Mastermind 23725 points
    Hi Olaf,

    mmWave devices are capable of measuring distance deltas within what you have specified. Implementation and post processing chains might differ based on your requirements.

    Please see this post which talks about higher accuracy and higher range resolution measurements:
    using Out of Box demo modification: e2e.ti.com/.../597434
    e2e.ti.com/.../2206436

    Update rates are configurable for mmWave devices and Out of box demo can be easily configured to have update rates higher than 20Hz and higher.

    Thank you,
    Vaibhav
  • 0 in reply to Vaibhav Mahimkar
    Intellectual 320 points

    Hi Vaibhav,

    Just to say it in different words: So the total distance between  RADAR sensor and 'reflecting target' can be 2cm (almost zero)?! I think I read something about the minimum distance of 1 m?

    Best regards,

    Olaf

  • 0 in reply to Olaf Albert
    TI__Mastermind 23725 points
    Hello Olaf,

    We have not extensively tried such short distances, however for point objects we believe this should not be an issue.
    For metallic objects at such close distance the power level of transmission will have to be significantly reduced.

    Are you thinking of concealing the sensor in an enclosure? That should be taken into account as added distance from from the sensor.

    Thank you,
    Vaibhav
  • 0 in reply to Vaibhav Mahimkar
    TI__Mastermind 23725 points
    Hello Olaf,

    Please let us know if you have more questions around this issue or if it is ok to close out this thread.

    Thank you,
    Vaibhav
  • 0 in reply to Vaibhav Mahimkar
    Intellectual 320 points

    Hello Vaibhav,

    Sorry for the late reply!

    To be honest: I hoped that you guys, having the demo on the desk, just give it a try.

    Yes we plan an enclosure but that is just <5mm more distance and I think that such a close distance will bring up some new effects for your IC beyond level limiting, like for example AM or PM noise effects which are not so prominent for larger distances.

    If this is too much effort (and I am fully aware of that I am not a premium customer ;-): please close the thread. Thank you!

    Best regards,

    Olaf

  • 0 in reply to Olaf Albert
    TI__Mastermind 23725 points
    Hello Olaf,


    On our current versions of boards we see an additional offset in measurements as mentioned in Doxygen help files of mmWave SDK Out of Box demo, this sets a lower limit on estimated values.

    A quick check with EVM booster boards show that Range profile graph continues to show variation to small changes in the distances even under 5cm. A good calibration paired with high accuracy algorithm like the one used in training.ti.com/mmwave-vital-signs-lab
    should be capable of such measurements.

    Thank you,
    Vaibhav