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IWR6843ISK-ODS: Meaning of the Range Bias and Rx Channel Gain/Phase Measurement and Compensation

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Replies: 2

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Part Number: IWR6843ISK-ODS

Hello,

I've been looking through the docs of the newest industrial toolboox (ver. 4.4.0) - the overhead 3D people counting lab, and noticed one of the requirements is stated to perform the Range Bias and Rx Channel Gain/Phase Measurement and Compensation in order to obtain calibration coefficients. 

1. I got curious: how does the aforementioned procedure (or lack of thereof) affects the detection and performance? Does it affect the coordinates of the point cloud and therefore the detection precision? If yes, in what way are the coordinates affected? - could you provide some examples of how the data quality is affected? 

2. In parallel, I was looking at the 3d point cloud demo and noticed that those coefficients are listed as "compRangeBiasAndRxChanPhase 0 -1 0 1 0 1 0 -1 0 -1 0 1 0 1 0 -1 0 -1 0 1 0 1 0 -1 0" in the provided default profile called "profile_iwr6843_ods_3d.cfg". Is there any reason why some of the coefficients are negative? - is it somehow related to the used firmware? I thought the default values should look like "compRangeBiasAndRxChanPhase 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0", so it would be great to get some clarifications on this point as well.

  • Hi Victoria,

    1. When the antenna is built, there are always some manufacturing tolerances in regards to the antenna. This procedure calibrates for those (so these coefficients are unique to each PCB). Essentially, we expect to see that the spacing between antennas is wavelength/2 - this will give a specific phase difference for any given angle an object is at. The calibration process determines the error in this value for IQ data for each Virtual Rx.

    2. On the ODS (and AOP) some of the antennas are upside down with respect to the rest of the antenna structure. The -1 relates to a 180 degree flip in phase.

    Regards,
    Justin

  • In reply to Justin Curewitz:

    Hi Justin,

    Thank you for the clarifications, it makes sense now.

    Best regards,

    Victoria

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