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AWR1642: The computation of angle

Rata Zhang
Expert 2840 points
Part Number: AWR1642

Hi，

   In the DSS demo,the azimuth is computed by searching  the peakvalue index  after  angle FFT, then the azimuth is wrong by this method if extendedMaxVelocityCfg.enabled=0 and V>Vmax.That is to say，if the relative speed V is greater than Vmax,extendedMaxVelocityCfg.enabled must be set to 1,the azimuth can be computed correctly,or the azimuth is wrong.Is that right?

Thanks in advanced,

Regards,

Rata

  • 0
    TI__Guru*** 148954 points
    Please let us know which version of the mmWave SDK you are using. Please make sure that you have downloaded the latest version mmWave SDK 1.2

    thank you
    Cesar
  • 0 in reply to Cesar
    Expert 2840 points

    Hi Cesar，

        I have downloaded the latest version mmWave SDK 1.2,I just want to know my understanding is right or not.In the version mmWave SDK 1.0.0.5,the extendedMaxVelocityCfg is not considered.I want to know if the relative speed is greater than Vmax,the parameter extendedMaxVelocityCfg.enabled must be set to 1,or the azimuth will be wrong.Is that right?

    Regards,

    Rata

  • 0 in reply to Rata Zhang
    TI__Mastermind 21025 points
    I'm not sure that your understanding aligns with the algorithm. Take a look at the demo's doxygen documentation here:

    C:\ti\mmwave_sdk_01_02_00_05\packages\ti\demo\xwr16xx\mmw\docs\doxygen\html\index.html

    and search for "Velocity disambiguation". In this section, it says that it handles target velocities > (2Vmax)

    -dave
  • 0
    TI__Expert 5235 points
    Your understanding is correct. Because we are doing TDM-MIMO, erroneous velocity estimation (which happens when V > Vmax(= lambda/(4*chirp-to-chirp period)) will also corrupt the angle (azimuth for 1642) estimation because of wrong doppler correction (based on this erroneous velocity estimate) across consecutive transmissions. When you enable the extended max velocity feature, it can correct velocities only up to 2Vmax but the angle estimation will work even if actual velocity was > 2 Vmax. In summary:

    If feature is not enabled and V > Vmax, both velocity and angle estimation will be wrong.

    If feature is enabled, both velocity and angle estimation will be good for V <= 2*Vmax, and for V > 2*Vmax, velocity estimate will be wrong but angle will be correct.

    Note also that this feature is exclusive with the multiObjBeamForming feature (if you try to enable both, you will get a configuration error). This means that when you enable the max velocity feature, you cannot detect up to two objects at the same range-doppler but different azimuth.