IWR6843AOP:

Hi Diana,

The source function is here, and it confirms that it's a one-sided CFAR. Note that this code is NOT intended for production use. It is NOT checked against any quality standards and should NOT be confused for an official TI software offering.

Best,

Nate

function [indxRangeSorted, indxDopplerSorted, fftOut2DMagSqRx1, noiseMeanMat] = detections_after_2D_fft(radar_data_2dfft, detection_options)

% Non coherent integration across antennas
fftOut2D = squeeze(sum(radar_data_2dfft.*conj(radar_data_2dfft),1));

% A bizarre matlab issue when there is only two dimensions, the squeeze
% command doesn't work.
if length(size(radar_data_2dfft)) == 2
fftOut2D = fftOut2D';
end


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Apply CA-CFAR for Object Detection %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

threshWinSize = detection_options.cfar_window_size; % Number of samples on each side of test cell to use for noise estimation
threshSkipSize = detection_options.cfar_guard_size; % Number of samples on each side of test cell to be skipped for noise estimation
detThreshdB = detection_options.cfar_threshold_db; % Scaling of detection threshold w.r.t surrounding noise level computed

%% 1D range dimension CFAR
% CFAR threshold computation, detection, local max check, etc. (implemented without for loop)
fftOut2DMagSqRx1 = squeeze(fftOut2D);

if detection_options.use_log_cfar == 1
fftOut2DMagSqRx1 = 10*log10(squeeze(fftOut2D));
end

if (size(fftOut2DMagSqRx1,1) > (2*threshWinSize+2*threshSkipSize+2)) && (detection_options.do_cfar_in_range == 1)
fftOut2DXtended = [fftOut2DMagSqRx1(end-threshWinSize-threshSkipSize+1:end,:); fftOut2DMagSqRx1; fftOut2DMagSqRx1(1:threshWinSize+threshSkipSize,:)];
% Construct in one-shot the cell-average( a.k.a mean noise floor) for each cell in the 2D Array.
noiseMeanMat = construct_noise_mean_mat(detection_options.cfar_method, threshWinSize, threshSkipSize, fftOut2DXtended);
% threshMat is a matrix of thresholds for each cell (size of threshMat is same as size of fftOut2D)
if detection_options.use_log_cfar == 1
threshMat = detThreshdB + noiseMeanMat;
else
threshMat = 10^(detThreshdB/10)*noiseMeanMat;
end
% Detection is based on cell exceeding threshold, as well as being a local maxima (in both dimensions)
threshDecisionMat = fftOut2DMagSqRx1 > threshMat;

else
threshDecisionMat = true(size(fftOut2DMagSqRx1 ));
noiseMeanMat = true(size(fftOut2DMagSqRx1 ));
end

%% Local Maxima
if detection_options.detect_only_local_maxima_in_range == 1
fftOut2DMagSqRx1Shiftm1 = [fftOut2DMagSqRx1(end,:); fftOut2DMagSqRx1(1:end-1,:)];
fftOut2DMagSqRx1Shift1 = [fftOut2DMagSqRx1(2:end,:); fftOut2DMagSqRx1(1,:)];
localMaxMat1D = and(fftOut2DMagSqRx1>fftOut2DMagSqRx1Shiftm1, fftOut2DMagSqRx1>fftOut2DMagSqRx1Shift1);
else
localMaxMat1D = true(size(fftOut2DMagSqRx1));
end

if detection_options.detect_only_local_maxima_in_doppler == 1
fftOut2DMagSqRx1Shiftm1 = [fftOut2DMagSqRx1(:,end) fftOut2DMagSqRx1(:,1:end-1)];
fftOut2DMagSqRx1Shift1 = [fftOut2DMagSqRx1(:,2:end) fftOut2DMagSqRx1(:,1)];
localMaxMat2D = and(fftOut2DMagSqRx1>fftOut2DMagSqRx1Shiftm1, fftOut2DMagSqRx1>fftOut2DMagSqRx1Shift1);
else
localMaxMat2D = true(size(fftOut2DMagSqRx1));
end

%% 2D vel dimension CFAR
if (size(fftOut2DMagSqRx1,2) > (2*threshWinSize+2*threshSkipSize+2)) && (detection_options.do_cfar_in_doppler == 1)
% CFAR threshold computation, detection, local max check, etc. (implemented without for loop)
fftOut2DMagSqRx1t = fftOut2DMagSqRx1';
fftOut2DXtended = [fftOut2DMagSqRx1t(end-threshWinSize-threshSkipSize+1:end,:); fftOut2DMagSqRx1t; fftOut2DMagSqRx1t(1:threshWinSize+threshSkipSize,:)];
% Construct in one-shot the cell-average( a.k.a mean noise floor) for each cell in the 2D Array.
noiseMeanMat_trans = construct_noise_mean_mat(detection_options.cfar_method, threshWinSize, threshSkipSize, fftOut2DXtended);
% threshMat is a matrix of thresholds for each cell (size of threshMat is same as size of fftOut2D)
if detection_options.use_log_cfar == 1
threshMat = detThreshdB + noiseMeanMat_trans;
else
threshMat = 10^(detThreshdB/10)*noiseMeanMat_trans;
end
% Detection is based on cell exceeding threshold, as well as being a local maxima (in both dimensions)
threshDecisionMat2D = fftOut2DMagSqRx1t > threshMat;
threshDecisionMat2D = threshDecisionMat2D';

% Only accept cells if threshold is exceeded and local maxima in both dimensions
localMaxMat = and(localMaxMat1D, localMaxMat2D);
detDecisionMat = and(threshDecisionMat, threshDecisionMat2D);
detDecisionMat = and(detDecisionMat, localMaxMat);
else
localMaxMat = and(localMaxMat1D, localMaxMat2D);
detDecisionMat = and(threshDecisionMat, localMaxMat);
end


% Detected Target Processing %
[indxRange, indxDoppler] = find(detDecisionMat);

[indxRangeSorted, sortedIdx] = sort(indxRange);
indxDopplerSorted = indxDoppler(sortedIdx);

end