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IWR1642BOOST: Point Cloud Azimuth Resolution, People Counting Lab

Thomas McCotter
Prodigy 110 points
Part Number: IWR1642BOOST
Other Parts Discussed in Thread: TIDEP-01000, IWR1642

Hello!

Can you point me to some information on how the additional azimuth resolution is calculated?  I believe it is part of the Capon Beamforming but I'm having trouble working my way through the math around that.  The device says it has a 120 degree field of view and when using 4Rx * 2Tx we get effectively 8 Rx.... which gives 120 / 8 and that describes that 15 degree azimuth resolution on the data sheet, right?  But, the data in the point cloud is in increments of 1.875 degrees? The azimuth but doesn't seem to actually be accurate to that level of precision (for example, an item that is 10cm wide may be represented by SNR/doppler values spanning azimuth increments totaling 30cm across at the correct range). It is definitely more precise than 15 degrees so the data is helpful.   Is there a way to get higher azimuth resolution?

Thanks

Tom

  • 0
    TI__Mastermind 23725 points
    Hi Tom,

    For angle estimation method used in People counting algorithm, details of Capon Beamforming can be found in the TID design TIDEP-01000 and can be searched online for theory details.

    Typically for angle estimation the number of range bins are increased by performing FFT with zero padding.
    Please check the doxygen help files found under IWR16xx's demo inside the SDK installation.

    We will get back to you with more details on paths for the same.

    Thank you,
    Vaibhav
  • 0 in reply to Vaibhav Mahimkar
    TI__Mastermind 30405 points

    Hi Tom,

    Please note the difference between angular resolution and angular accuracy as mentioned in the People counting TI Design documentation as mentioned below:

    Angular resolution – This is defined as the minimum angular difference over which the detector can distinguish two individual point targets that also happened to have the same range and velocity. This is determined by the number and geometry of the antennas in the transmit and receive antenna arrays. This is typically specified separately for the azimuth and elevation.

    Angular accuracy – This is often defined as a rule of thumb formula for the variance of the angle estimation of a single point target as a function of SNR.

    I would also like to clarify on your assumption regarding the 15 degree angular resolution, given below:

    @Tom: The device says it has a 120 degree field of view and when using 4Rx * 2Tx we get effectively 8 Rx.... which gives 120 / 8 and that describes that 15 degree azimuth resolution on the data sheet, right?

    Angular resolution is a function of the number of virtual RX antennas and is given as 2/N radians which is equal to 2/8 i.e. 1/4 radians (or ~15 degrees)for the IWR1642. It is not dependent upon the field of view.

    Please refer to the following threads which discuss this topic in detail along-with the theoretical and achievable accuracy calculations based on SNR.

    Range, velocity, angle accuracy

    IWR1443BOOST: The Performance for the ROS visualizer lab

    Please mark this thread resolved if your question was answered otherwise get back if more support is needed.

    Thanks

    -Nitin