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IWR6843ISK: Questions about "Long Range People Detection" Demo

Jarry Fan
Prodigy 30 points
Part Number: IWR6843ISK
Other Parts Discussed in Thread: DCA1000EVM,

Hi, Ti

        When I use the Long Range People Detection Demo（dev.ti.com/.../node, there are some questions:

1. Why is the beamwidth 22.5 degrees, can we modify the beamwidth, and if so, how is the beamwidth modified?

2. If the beamwidth is 22.5 degrees and the azimuth is 0 degrees and the perceived range is 7 meters, then the perceived FOV is [-11.25°, +11.25°]? That is to say, it will not be disturbed by moving targets other than FOV?

3. I use IWR6843ISK+DCA1000EVM hardware and the config file "6843_100m_2D_advanced.cfg", we only modify the following configuration to collect data. We set the data collection time to 30 seconds, but actually only 6 seconds of data can be collected. By calculation I think the parameter setting requirements are met, but it doesn't seem to work properly. May I know what is the reason?

profileCfg 0 60 70 7 30 0 14970880 100 1 64 5333 0 0 48
profileCfg 1 60 70 7 30 0 10276864 100 1 64 5333 0 0 48
profileCfg 2 60 70 7 30 0 6565888 100 1 64 5333 0 0 48
profileCfg 3 60 70 7 30 0 1871872 100 1 64 5333 0 0 48
%
chirpCfg 0 0 0 0 0 0 0 7
chirpCfg 1 1 1 0 0 0 0 7
chirpCfg 2 2 2 0 0 0 0 7
chirpCfg 3 3 3 0 0 0 0 7
%
advFrameCfg 4 0 0 1 0
%
subFrameCfg 0 0 0 1 48 15 0 1 1 15 
subFrameCfg 1 0 1 1 48 15 0 1 1 15 
subFrameCfg 2 0 2 1 48 15 0 1 1 15 
subFrameCfg 3 0 3 1 48 15 0 1 1 15 

Thank you very much!

  • 0
    TI__Mastermind 19270 points

    Hello.

    I am discussing the first two questions internally and will get back to you by tomorrow on those details.  For the third question, please check your frame periodicity as well as your number of frames, which is what determines how long the data collection will last.

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Prodigy 30 points

    Hi Santosh，

    Thank you for your reply. I'm sorry that I was not descript the third question. I use the command "./DCA1000EVM_CLI_Control start_record/stop_record configFile.json" to control start/stop data acquisition. I set the parameter captureStopMode to infinite in configFile.json. I think it will keep capturing data until I send the command "./DCA1000EVM_CLI_Control stop_record configFile.json". I want to collect data for 30 seconds and then send the stop command, but it only works for 5 seconds and then quits automatically. I don't know what's causing this.

    Sincerely,

    Jarry

     

  • 0 in reply to Jarry Fan
    TI__Mastermind 19270 points

    Hello.

    If you look up the DCA1000 CLI user guide, you can find examples of how they created config json files for data capture.  In an example, despite setting the captureStopMode to infinite, they still set an appropriate bytes to capture, duration, and frames to capture, which might be what is causing your data capture to end early.  Can you try modifying these things and see if it now captures for 30 seconds or if it still only captures for 5 seconds?

    With regards to your other questions, you can change the beamwidth by modifying the txPhaseShifter value.  You can refer to the Beamforming_in_LRPD.pdf linked here to learn how to change it.  However, 22.5 degrees is recommended as it has a stronger signal strength and can detect people farther away much better.

    For your second question, are you talking about the FOV of each beam or the beam scanning over the full FOV?

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Prodigy 30 points

    Hi,

    Thank you for your reply. For the third question, I solved it by modifying the config parameter. 

    But, for the first question, I still don't understand why the beamwidth is 22.5 degrees. I have read Beamforming_in_LRPD.pdf. However, I think the beam direction is changed by modifying phaseShifterValue, and I also refer to zigang' answer about https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/987243/iwr6843isk-beamsteering-question/3650082. so, can you explain what the single beam widths are related to?

    For the second question, I'm talking about the FOV of each beam.

    Sincerely,

    Jarry

  • 0 in reply to Jarry Fan
    TI__Mastermind 19270 points

    Hello Jarry.

    Jarry Fan said:
    However, I think the beam direction is changed by modifying phaseShifterValue,

    This phaseShifterValue that Zigang references is the txPhaseShifter parameter that is part of the profileCfg.  You can get more information on this from the sdk user guide.

    Jarry Fan said:
    But, for the first question, I still don't understand why the beamwidth is 22.5 degrees.

    In the user's guide for LRPD under the section How Beamforming and Beamsteering Works, there is a paragraph that explains the decision to use 22.5 degree wide beams.

    Jarry Fan said:
    For the second question, I'm talking about the FOV of each beam.

    If you consider the center of each beam to be 0 degrees, then yes the FOV is from [-11.25 to 11.25] degrees.  However, the way LRPD works is that it configures 4 subframes, and in each subframe a beam is pointed in a different direction.  With all 4 of the beams combined, you will be able to detect people within [-45 45] degree FOV.  This is also all documented in the LRPD user guide under How Beamforming and Beamsteering work.

    Hope this helps,

    Santosh