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TIDEP-01012: Large sidelobes in TXBF captures

Dayalan Nair
Prodigy 220 points
Part Number: TIDEP-01012

Hello.

The reference design document shows that the beamforming capture, in an anechoic chamber after calibration, has lower sidelobes than that which can be seen in my capture. I performed calibration indoors and obtained a decent calibration LUT, however this was not performed in an anechoic chamber. Is this the reason for the sidelobes?

My calibration matrix:

My results:

The scene:

The expected result from the reference design (right figure):

  • 0
    TI__Mastermind 20605 points

    Hi Dayalan,

    Please find my comments below.

    • It is always suggested that you perform calibration in an anechoic chamber for best results.
    • From your calibration matrix, I can't make out much. This can differ quite a bit from chip to chip and from one calibration environment to another.
    • For your heatmap comparison, would it be possible to depict in the same fashion as done in the reference guide? This can help visualize the error to a better degree.
    • Looking at your scene and second plot, it does look like there might be a slight deviation that could be caused by calibration. Would suggest you perform the same test inside a room while facing a flat wall of uniform surface once if possible.

    Regards,

    Kaushik

  • 0 in reply to Kaushik Gowda
    Prodigy 220 points

    I am quite certain the error is due to imperfect calibration, since the reflector was not positioned exactly in line with board center and calibration was performed in a relatively small room. Here is the 3D plot/s as requested. I notice a raised level at the furthest range at all angles. Do you have an idea of what this could be?

  • 0 in reply to Dayalan Nair
    TI__Guru 69960 points
    Dayalan Nair said:
    calibration was performed in a relatively small room

    Small room was anechoic chamber? no reflection except corner reflector?

    Calibration must perform with this condition where it should have any reflection other than corner-reflector at zero angle.

    Please consider this for your experiment.

    .

    Regards,

    Jitendra

  • +1 in reply to Jitendra Gupta
    Prodigy 220 points

    Hi, 

    We managed to acquire additional office space with access to a large, open room. Both the RX and PS calibration results are looking better. I will continue testing with the improved calibration matrices and update this thread as needed. So far, the latest RX calibration has drastically improved the angular resolution of the platform. 

  • 0 in reply to Dayalan Nair
    Prodigy 220 points

    Ofcourse, the best results would come from an anechoic chamber which we will use if we need better performance.

  • 0 in reply to Dayalan Nair
    TI__Mastermind 20605 points

    Hi Dayalan,

    Glad to hear that you are able to progress. Will be closing this thread for now.

    Regards,

    Kaushik