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AWR1443BOOST: Measuring Speed

Mitchell
Expert 4915 points
Part Number: AWR1443BOOST
Other Parts Discussed in Thread: AWR1642

Hi Team,

My customer is evaluating the AWR1443BOOST using the demo FW / out of box demo v1.2. In their setup, they wrote python script that reads messages from EVM and parses them. 

They did some tests at their desk, where they waved a metal object in front of the radar, but it never recorded anything more than +/-1m/s. Although, we are certain the movement was faster. Another experiment was performed where the device was mounted into a car. While driving around, it detects objects and relative speed but again the speed was never more then 1m/s.

We looked at the raw data and the values reported there is just in small range around 0. I'm sure that relative speed between other cars and ours was more than 1m/s.

Any ideas on what we could be doing wrong?

Thanks,
Mitchell

  • 0
    TI__Guru*** 147964 points
    Hi,

    First, I think it would be helpful to understand what the expected maximum speed is.
    Please see mmwave training to understand the definition of maximum speed in relation to the mmwave chirp.

    training.ti.com/mmwave-training-series


    Second, please check in the chirp configuration used for tests above, what the expected maximum velocity is.

    We have several demos on AWR1642 (SRR...) where we measure expected speed.

    thank you
    Cesar
  • 0 in reply to Cesar
    Prodigy 10 points
    Hi,
    Expected doppler speed of detected objects should be in the range of up to +/-10m/s.
    Data was collected in the car, driving on the highway, driving by slower cars, approaching them or driving behind faster car.

    Looking at the raw data from the EVB 1443 it seems that doppler Index value changes very little, just +/-4
    Looking through the documentation and forum answers I found this formula for speed calculation:

    # ( speed of light(3e8) / (2 * (startFreq * 1e9) * ((idleTime + rampEndTime) * 1e-6) * numChirpsPerFrame) )

    And here is python code where I just hardcoded values from configuration parameters

    c = 3e8
    startFreq = 77
    idleTime = 48.98
    rampEndTime = 438
    numChirpsPerFrame = 2 * 16
    dopplerResolutionMps = c / (2 * (startFreq * 1e9) * ((idleTime + rampEndTime) * 1e-6) * numChirpsPerFrame)
    index = self.dopplerIdx
    sign = 1.0
    if self.dopplerIdx >= (32768):
    index = 65536 - self.dopplerIdx
    sign = -1.0
    self.speed = sign * index * dopplerResolutionMps

    Is formula correct? If not, what should I be using?
    And why is doppler Index value changing in very narrow range?

    Thanks
    Martin
  • 0 in reply to Martin Junkar
    TI__Guru*** 147964 points
    Hi,

    In the training that I mentioned in the previous post, Vmax = lambda/(4Tc) where Tc is total chirp time, including idle time.
    lambda = c/f ~ 3.9mm (when f = 77Ghz)

    In the config you provided, Vmax ~ 3.9 m/s

    I think that this is what you observed

    thank you
    Cesar