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AWR1642BOOST: Doppler-Range-Heatmap - Level interpretation

Alessandro
Prodigy 180 points
Part Number: AWR1642BOOST

Hi,

I am working with the doppler-range-heatmap and I am wondering about the levels (colors).

In the range profile for zero velocity (doppler = 0) the power levels are given in dB. In the heatmap instead we get levels like 4000, 5000 and so on.

How is the relation between the range profile power levels and the doppler-range-heatmap power levels?

I would also have this question for the variable "peakVal" in the javascript code of the mmWave DemoVisualizer.

Could you explain these relationships?

Thank you,

Alessandro

P.S.: Actually I'm using firmware version: mmWave SDK 1.1.0.2.

  • 0
    TI__Guru*** 149204 points
    Hi,

    There are some related threads.

    It would be helpful to search the forum for "demo units" and "peakVal"

    thank you
    Cesar
  • 0 in reply to Cesar
    Prodigy 180 points
    Hi Cesar,

    I understand that a higher "peakVal" corresponds to a higher signal strength (information found in other threads).

    In the range profile the y-axis shows the signal strength in dB with reasonable values. If I cut the range-doppler-heatmap at doppler = 0 and if I do the comparison to the range profile (directly output by the sensor) I get a very good matching between these two curves. This means that the range-doppler-heatmap seams to be in a logarithmic scale, too. I am interested in the relationship between these two curves. Why do the values differ from each other? How can I transform the "heatmap peakVals" to the "range-profile peakVals"?

    Thank you.
    Alessandro
  • 0 in reply to Alessandro
    TI__Guru*** 149204 points
    Hi

    The range profile and the noise profile that we display in GUI are just the two columns of the same range detection matrix used for displaying range/Doppler heat-map, range profile is a zero Doppler column and noise profile is a N¬dop_fft/2-1 column. Each element of the detection matrix is a sum (or average in awr14xx)of log2 magnitudes of 2D FFT values across antennas. The log2 magnitude is in Q8 (awr16xx) or Q9 (awr14xx) format. So, on awr16xx, to get heat-map values to dB need to do the same calculation as is used to convert range profile to dB
    Value in dB = received value * 20*log10(2) / (256 * numTxAnt * numRxAnt) + some dB offset related to FFT size scale compensation in 1DFFT and 2DFFT (see processRangeNoiseProfile(), dspFftScalComp1() and dspFftScalComp2() in mmWave.js)

    Again the peakVal in the cloud point is the energy at range,Doppler,Azimuth index, while the corresponding peak in the Range/Doppler heat-map correspond to the energy of all cloud points at that range/Doppler index (may include more targets (detected or not detected) coming from different azimuth angles). Also there is difference in the computation. In the heat-map we do sum of log2 magnitudes across antennas (approximation function), while the peakVal in cloud point is coming from azimuth FFT peak as a square root of the sum of magnitude squares across antennas.

    Thank you
    Cesar
  • 0 in reply to Cesar
    Prodigy 180 points

    Hi Cesar,

    thanks for your explanations. We will have a closer look on it as soon as possible. We will try to reopen the thread if there are questions related to this issue.

    Thank you,

    Alessandro