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Original question:

IWR6843: Interfacing IWR6843 through UART to send Config data

IWR6843: IWR6843-ODS ceiling mount questions

Samidha Buriwar
Prodigy 175 points
Part Number: IWR6843
Other Parts Discussed in Thread: , , UNIFLASH

Hi,

I am using IWR6843 ODS EVM for people counting in a ceiling mount installation type.

I have some questions regarding the same :

  1. What are the minimum and maximum heights the board can be mounted? and How it affects the FOV?
  2. Is the calibration step important? how much accuracy will be affected if not calibrated?
  3. The board is installed on the metal box with packaging in between. Will this metal affect the working? (metal is on the back side of the antenna).

Thanks and Regards,

Samidha Buriwar

  • 0
    TI__Genius 14415 points

    Hello Samidha,

    1. There is no minimum or maximum mounting height, it will just change the FOV. The FOV is +-60 degrees in each direction from the boresight axis of the sensor, so depending on how high the sensors is mounted, a larger or smaller detection area along the floor will be enabled. You will need to just use the FOV geometry to determine this for your mounting height. If the sensor is too far from the floor, the detection may return lower SNR points (>5m from the ground)

    2. The calibration is required for some applications. It will improve the angle accuracy at the edge of the field of view. If this accuracy is very critical for accurate positioning (<~0.5 m) then calibration should be used. If absolute location is not strictly required (count of people is more important than position) it is likely not required.

    3. The metal behind the sensor should not affect the sensor if it is completely behind the sensor. If it protrudes out, even to the side of the radar, it could affect the FOV. 

    Regards,

    Jackson

  • 0 in reply to Jackson Thomas
    Prodigy 175 points

    Hi Jackson,

    Thank you for the prompt reply. I have some more queries and will be happy if you help me solve them.

    I have 2 EVMs IWR6843AOP EVM and IWR6843ISK-ODS EVM. I have flashed both with the overhead_3d_people_counting default code using Uniflash, and used the chirp configs pc_6843_3d_aop_overhead_3m_radial and pc_6843_3d_ods_overhead_3m_radial respectively.

    I have observed that IWR6843AOP EVM works very well in terms of counts (number of Target) as well as their coordinates, but I am not getting a similar result for IWR6843ISK-ODS EVM. It only detects people if they are close by under the board and then tracks them. Sometimes it doesn't even detect people no matter how much they move.

    Am I missing anything in here?

    Thanks and Regards
    Samidha

  • 0 in reply to Samidha Buriwar
    TI__Genius 14415 points

    Hello,

    Which version of the toolbox are you using? In 4.11 it looks like the only difference is that the AOP configuration uses higher TX power. This could certainly cause the behavior you are seeing but in a clear environment with low mounting height I don't think it should. What is your mounting setup, and is it common between the 2 boards?

    Regards,

    Jackson

  • 0 in reply to Jackson Thomas
    Prodigy 175 points

    Hi Jackson,

    I am using the 4.10.1 version. The setup for both is almost the same. The mounting height for ODS is 2.6m and the AOP one is 3.3m. Both are installed above desks in an office.

    I have figured out that the TX power is causing the difference in behavior. For AOP it is 328965 and for ODS it was 657930.
    When I changed the ODS one to 328965 it is working fine.

    It seems that the TX power effects on the counts and functionality is high. I would be happy if you shed some light on this.

    I want to compare both boards to finalize one to use further. I was thinking to install it on the ceiling side by side so that I can compare the results.
    Do you think it is a good idea or are there any chances that the waves can get interfered with each other and affect the functionality?

    Thanks and Regards,

    Samidha

  • 0 in reply to Samidha Buriwar
    TI__Genius 14415 points

    Hello,

    Lower TX power will see less reflection from the walking person, so it is expected to see worse performance. 

    You should be able to mount the boards closely without interference. It is possible there is some interference if they are too close and pointing at the ground, a common flat surface. But I would expect both to be able to work. I recommend that you test with both chirping simultaneously, then test with each individually in the same mounting position. This will show if there is any delta in performance from the proximity.

    Regards,

    Jackson