IWR6843ISK: what to indicate by range - azimuth heat map

Hello,

The range-angle heatmap in the papers you linked is calculated using a different method than is done in the mmWave Online Visualizer.

In TI's mmWave Demo, the range azimuth heatmap is calculated from a subset of the radar-cube correlating to the zero doppler bin (so no movement information). So we only take the 0 doppler information for every range, angle bin combination. Additionally the visualizer converts the information from polar (range,angle) to Cartesian coordinate system so x,y in meters are the axes of the plot.

In contrast, the paper you linked takes the doppler bin of the highest energy value, and computes the range angle estimation for that doppler bin. You can  think this range-angle heatmap as representative of either moving or non moving objects depending on the range/angle combination.

If you want to implement the same, you will need to stream out the entire radar-cube and perform the computations as described in the paper. https://e2e.ti.com/support/sensors/f/1023/p/885225/3329328#3329328

Amanda

understand_OOB_output.pdfHello,

I've attached a document for the OOB UART data.

To parse and reconstruct the plot for the azimuth heatmap TLV please see this pseudocode/Matlab snippet

    
    % payload is array of unsigned bytes in azimuth heatmap TLV
    q = payload(1:2:end)+payload(2:2:end)*256; % convert to uint16
    q(q>32767) = q(q>32767) - 65536; % convert to signed
    q = 1j*q(1:2:end)+q(2:2:end); %convert to complex. Imaginary first, real second
    q = reshape(q, numVirtualAntenna, numRangeBins); %convert from array to 2d matrix of dim [# virtual ant] x {# range bin]
    Q = fft(q, NUM_ANGLE_BINS); % numAngleBin-point fft along columns (across virtual ant)
	
    theta = asind([-NUM_ANGLE_BINS/2+1 : NUM_ANGLE_BINS/2-1]'*(2/NUM_ANGLE_BINS));
    range = raneqBin2Meters; %rangeBin2Meters is an array from 0:range_resolution_bin:maxRange of the chirp
    posX = range' * sind(theta');
    posY = range' * cosd(theta');
    xlin=linspace(-floor(range(end)),ceil(range(end)),200);
    ylin=linspace(0,ceil(range(end)),200);
    [X,Y]=meshgrid(xlin,ylin);

    QQ = fftshift(abs(Q),1);
    QQ=QQ.';
    QQ=QQ(:,2:end);
    Z=griddata(posX,posY,QQ,X,Y,'linear');
    hAzimuthHeatmapPlot = surf(xlin,ylin,Z);
    shading INTERP
    view([0,90])
    axis('equal')
    axis([-ceil(range(end)) ceil(range(end)) 0 ceil(range(end))])
    xlabel('Range X-Axis [m]');                  
    ylabel('Range Y-Axis [m]');

Amanda