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IWR6843ISK-ODS: IWR6843 MultiGesture demo

Notozman
Expert 7536 points
Part Number: IWR6843ISK-ODS

Team, 

Looking at the latest Multi-gesture demo in the 3.4 toolkit - we are measuring 330ma for all modes of this demo meaning the same power whether detecting motion, or gesture or no detection at all. Is there a lower-power mode that can be implemented or enabled for at least when we are in the "N" mode ? 

Also I read in the code that there are 2 TX antennas and 1 RX used. However if I look at the hard coded cfg then I see 2 TX and 4 RX enabled. Which one is it ? And can we maybe change the hard-coded config to drop power ?

Thanks. 

  • 0
    TI__Mastermind 30405 points

    Hi Greg,

    The demo does not implement and switch to a low power profile in presence detection mode. The "No person detected" indication is provided to allow a GUI  to switch to low power mode (shut-down the screen etc), as stated in the user guide.

    "Such a system can be used to implement gesture based Human Machine Interfaces (HMI) which switch to a low power mode for motion/presence detection when someone is not around and switch to gesture detection mode when motion is detected near the sensor."

    Hence the mmwave sensor current draw does not change whether it's in motion or gesture detection mode. While it is possible to implement a system where the sensor itself switches to a low power profile, this is outside the scope of this particular demo. This behavior has been the same across industrial toolbox releases since the demo was released.

    Secondly, all 4 RX antennas are used in the demo. The demo uses Angle of Arrival information for gesture detection and it is not possible to get Angle information with a single RX antenna. I believe you are referring to the following comment in mss_main.c but note that it relates only to the pre-detection matrix computation which is performed on 1 RX antenna in this case. But the DOA computation does use symbols from all 4 RX antennas. Please look at the function Computefeatures_DOABased in file dss/gesture.c

    * The reason why only a single Rx antenna is used is because there was no 
* performance degradation with only a single Rx antenna.
*
* The reason for the limited range is because gestures are expected to be
* performed close to the Radar.

    Hope this answers your questions.

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    TI__Mastermind 30160 points
    Hi Nitin,

    Are there any IWR6842 lab/demo that is supporting a low power profile today in the Toolbox 3.4.0?
    Are there plan to implement a demo that would typically:
    use less antenna to detect movement (to save power) and when detected use the other antenna to get better accuracy?

    Thanks in advance,
    A.
  • 0 in reply to Nitin Sakhuja
    TI__Mastermind 30160 points

    Nitin,

    Nitin Sakhuja said:
    I believe you are referring to the following comment in mss_main.c but note that it relates only to the pre-detection matrix computation which is performed on 1 RX antenna in this case. But the DOA computation does use symbols from all 4 RX antennas.

    I am not familiar with what you call pre-detection and DOA. Could you please expend?
    Could movement detection be done in 1 single RX antenna in order to save power?

    Thanks,
    A.

  • 0 in reply to AnBer
    TI__Mastermind 30405 points

    Hi AnBer,

    Please look at the mmwave demo doxygen documentation provided under C:\ti\mmwave_sdk_02_01_00_04\packages\ti\demo\xwr16xx\mmw\docs\doxygen\html\index.html to understand the basic mmWave processing chain. DOA stands for Direction of Arrival, i.e. Angle of Arrival.

    With a single RX antenna, you can do movement detection only in 1D space i.e. get distance information but to get the location in 2D or 3D space, you need more than 1RX antenna and the higher the number of effective RX antennas the better the angle estimation is.

    You can look at the videos provided under mmWave Training Series to understand the fundamental concepts of FMCW Radar Signal processing (i.e. Range, Velocity and Angle of arrival estimation). Also look at the MIMO Radar App note to understand concepts such as Virtual antenna arrays, relation between number of antennas and Angular Resolution).

    Regards

    -Nitin