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IWR6843: Visual Demo only showing objects when detecting moving objects

XINJUN DONG
Intellectual 300 points
Part Number: IWR6843
Other Parts Discussed in Thread: MMWAVEICBOOST,

Hi there, 

I am using IWR6843ISK with the MMWAVEICBOOST. I am currently using the mmWave demo visualizer, but I found a problem. 

From the plot, it seems that the sensor only detected objects when it is moving but did not show when it is static. I have made sure that the clutter removal is disabled when configuring the sensor. Following is the .config file I download from the visualizer. 

% ***************************************************************
% Created for SDK ver:03.01
% Created using Visualizer ver:3.1.0.1
% Frequency:60.25
% Platform:xWR68xx
% Scene Classifier:best_range_res
% Azimuth Resolution(deg):15 + Elevation
% Range Resolution(m):0.047
% Maximum unambiguous Range(m):9.02
% Maximum Radial Velocity(m/s):3.99
% Radial velocity resolution(m/s):0.25
% Frame Duration(msec):100
% Range Detection Threshold (dB):15
% Doppler Detection Threshold (dB):15
% Range Peak Grouping:enabled
% Doppler Peak Grouping:enabled
% Static clutter removal:disabled
% Angle of Arrival FoV: Full FoV
% Range FoV: Full FoV
% Doppler FoV: Full FoV
% ***************************************************************
sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 15 7 0
adcCfg 2 1
adcbufCfg -1 0 1 1 1
profileCfg 0 60.25 50 7 53.57 0 0 70 1 224 4915 0 0 30
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 4
chirpCfg 2 2 0 0 0 0 0 2
frameCfg 0 2 32 0 100 1 0
lowPower 0 0
guiMonitor -1 1 1 0 0 0 1
cfarCfg -1 0 0 8 4 4 0 1280 1
cfarCfg -1 1 0 8 4 4 1 1280 1
multiObjBeamForming -1 1 0.5
clutterRemoval -1 0
calibDcRangeSig -1 0 -5 8 256
compRangeBiasAndRxChanPhase 0.0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
measureRangeBiasAndRxChanPhase 0 1.5 0.2
aoaFovCfg -1 -90 90 -90 90
cfarFovCfg -1 0 0 8.42
cfarFovCfg -1 1 -4 4.00
sensorStart

Any help would be appreciated. 

Thanks in advance

  • 0
    TI__Mastermind 30405 points
    Hi Xinjun,

    A few things to check:

    1. Do you see peak(s) corresponding to the object in the zero-doppler range FFT plot? The XY scatter plot shows only those detected objects which pass the CFAR detection thresholds (range and Doppler) but the Range FFT plot shows all frequency peaks in the Zero-Doppler spectrum. Further, the peaks which pass the CFAR thresholds are marked with orange dots in this plot.

    2. Looking at the Zero-Doppler Range FFT plot, make sure the object of interest has enough range separation (at least range-resolution) from any surrounding objects (especially stronger reflectors) otherwise the frequency peaks of the two objects will merge and appear as one.

    3. Using the Real-Time Tuning Tab in the Visualizer, disable peak grouping to enable more detected points per object. Peak grouping shows only the strongest one of neighboring points (range and/or Doppler) thus reducing the number of detected points for the object.

    4. Using the Real-Time Tuning Tab in the Visualizer, try lowering the range CFAR threshold to enable more points.

    Regards
    -Nitin
  • 0 in reply to Nitin Sakhuja
    Intellectual 300 points

    Nitin,

    Thanks for the reply. I have tried to play with those settings and it is getting better now. I will keep trying to find a better combination of those settings. 

    I have a quesiton about CFAR range threshold value. I saw that the default value is 15 db, so I assume that if the peak value at zero doopler plot is larger than 15db, it will be considered as detected objects. However, I saw some peak values are larger than 15db but still not plotted as orange dots. 

    Please let me know if my understanding is incorrect. 

    Best, 

    Xinjun

  • 0 in reply to XINJUN DONG
    TI__Mastermind 30405 points
    Hi Xinjun,

    The CFAR algorithm compares a peak (Cell under test) with it's surrounding peaks and considers the peak a valid detection of it exceeds a configured threshold. There are variations on how the threshold is computed (CFAR-CA, CFAR-CAGO, CFAR-CASO etc). In other words, the decision to mark a peak as a detection is based on relative magnitude wrt it's neighbors. The number of left and right neighboring cells is also configurable as window length. Please look at the SDK user guide for details of the CFAR configuration parameters.

    Regards
    -Nitin