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IWR6843ISK-ODS: Is there a generic recommendation on the Tx muting codes defined by profileCfg?

Victoria Rudakova
Intellectual 770 points
Part Number: IWR6843ISK-ODS

Hello TI team,

I've been trying to understand how the Tx muting codes affect the point cloud data. I work with a very sensitive chirp configs (about 0.01-0.08 m/s velocity resolution) and normally get lots of reflections within a confined space (walls, monitor, desk, etc.), even I filter out static points. I noticed those reflections could be diminished by using the Tx muting parameter.

1. Are there any general recommendations on how to chose that parameter? For example, is it correct to assume that I would want to mute more for lower installation heights - for example, for 2.5 meter height I would use 12 dB and for 4 meter install I would use 2 dB. 

2. What is the best approach in selecting the muting value? Should I just look at the point cloud data and try different dB values and see what looks the best from my perspective? Does TI have any recommendations on the values?

3. What is the max muting value, in dB? 

Thank you.

Best regards,

Victoria

  • 0
    TI__Guru 50240 points

    Hi Victoria

    Can you discuss your application for more context?

    Also which chirp config and demo are you using?

    Regards,

    AG

  • 0 in reply to Akash Gondalia
    Intellectual 770 points

    Hello Akash,

    The application is ceiling-mount mmWave device inside of an office environment: offices, conference rooms, open offices, office kitchen. That is, the scene would have desks, chairs, tables, walls, people. The installation height ranges 2.5-4.5 meters. 

    I am currently using a 3D point cloud demo (FFT-based firmware). I try different chirp configs with slight variations in terms of FPS, velocity resolution, range, etc., but they are all similar to the chirp config from the Overhead 3D People Count lab:

    profileCfg 0 60.0 60 17 50 0 0 55.27 1 64 2000 0 0 40 

    frameCfg 0 2 224 0 120.00 1 0

    The above has no Tx muting, but I'd like to understand what is the best way to use it across different installation heights.

    Thank you.

    Best regards,

    Victoria

  • Former Member
    0 Former Member in reply to Victoria Rudakova

    Hello Victoria,

    By TX muting I assume you mean TX backoff in the profileCfg.

    Applying TX backoff effectively reduces radiated power and SNR of returned signal.

    When you increase the backoff value likely the SNR decrease results in less points passing the CFAR detection thresholds and this is why you see less points.

    It is difficult to say whether this approach is good for your application. The trade off may be that the object of interest for you is also more difficult to detect.

    In general, however I would agree that at a lower mounting height you would want more TX backoff or reduced RX gain than a higher mounting height. This is because in an overhead mount position the sensor is directly facing the floor which can cause strong reflections that effectively raise the noise floor and adversely affecting the SNR of your signal.

    There are likely several ways toreduce these undesired reflections and they likely will have to be empirically derived as you described by observing the effect on the point cloud.

    Other ideas I would suggest include experimenting with increasing CFAR thresholds, filtering out points by Doppler or SNR.

    Amanda