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IWR6843AOPEVM: Calibration Procedure - Issues with MeasureRangeBias Configuration

Colin Soguero
Prodigy 10 points
Part Number: IWR6843AOPEVM

Hi,

I have some confusion regarding the proper steps for calibrating my sensor that I believe is resulting in inaccurate calibration results. In the calibration procedure located at C:/ti/mmwave_sdk_03_06_00_00-LTS/packages/ti/demo/xwr68xx/mmw/docs/doxygen/html/index.html#Calibration_section, Step 3 simply states: “Start the sensor with the configuration file”. These are the steps I followed for starting the sensor with the configuration file:

  1. With the Out of Box Demo loaded on the board I opened up the online visualizer and configured the settings for my board.
  2. In the profile_calibration.cfg located at C:/ti/mmwave_sdk_03_06_00_00-LTS/packages/ti/demo/xwr68xx/mmw/profiles/, I edited the values of the measureRangBiasAndRxChanPhase command to be <1 2.58 0.2> to match the distance between the target reflector and the sensor in my setup.
  3. I uploaded the profile_calibration config using the “LOAD CONFIG FROM PC AND SEND” button under the plots tab. On my initial attempt of doing this I got the message: “Error: Invalid configuration. bpmCfg command not supported”. After commenting out the bpmCfg line in the config file I was able to load the config successfully.

I should note the whole time while I was following these steps, compRangeBiasAndRxChanPhase values were being continuously printed to the console in the visualizer. This was true both before and after I uploaded profile_calibration.cfg.

When I went to “Save config to PC” from the main tab, I noticed the config file that gets downloaded is not the same config that I uploaded and the measureRangBiasAndRxChanPhase values of <1 1.5 0.2> are not the same values I set in profile_calibration.cfg. Additionally, when I update the calibration coefficients using the compRangeBiasAndRxChanPhase values that were printed to the console, the tracking alignment becomes much worse than when I use the default values which reaffirms my belief that the incorrect config file, and by extension the incorrect values for the measureRangBiasAndRxChanPhase command, are being ran on the sensor.

My questions are: Is this the correct procedure for running the calibration? And how do I start the sensor with the correct config file (profile_calibration.cfg) in the online visualizer?

  • +1
    TI__Expert 4448 points

    Hello,

    First, I would like to point you to the SDK User's Guide (C:/ti/mmwave_sdk_03_06_00_00-LTS/docs/mmwave_sdk_user_guide.pdf) section titled "Range Bias and Rx Channel Gain/Offset Measurement and Compensation" on page 75. This section gives a little more context on the calibration process specifically using the Visualizer GUI. 

    Second, it sounds like you are following the correct procedure generally, but I do have a few concerns & questions. 

    Colin Soguero said:
    I should note the whole time while I was following these steps, compRangeBiasAndRxChanPhase values were being continuously printed to the console in the visualizer. This was true both before and after I uploaded profile_calibration.cfg.

    The terminal messages window on the Configure Tab should dump a compRangeBiasAndRxChanPhase commands ONLY when the first parameter of measureRangBiasAndRxChanPhase is equal to 1. This will be the case when using the profile_config.cfg, but it is odd that this was being printed prior to you sending that config too. If you send the basic config from the OOB demo (or remove the command or change the first 1 to a 0), does that stop the compRangeBiasAndRxChanPhase output in the console? Please, ensure that you are following the correct procedure for using the visualizer as stated by the OOB Demo. 

    When you update the config with the compRangeBiasAndRxChanPhase that are output, are you then removing the measureRangBiasAndRxChanPhase command too? Are you then sending that newly modified config to the device in the visualizer?

    Do not worry about the "bpmCfg command not supported" error, comment it out of the config as you did. Also, due to the backend construction of the visualizer tool, uploading a config does not change the values in the file you receive from "Save config to PC". only changing the slider values modify the downloaded file.

    If double-checking these does not seem to fix the apparent lack of accuracy, can you please explain exactly what you mean by "tracking alignment", how you're evaluating it, and the conditions that make it better and worse?

    Regards,

    Luke