cfar.m

阵列信号处理的工具箱

function [sigOut] = cfar(sigIn)

% *****************************************************************************
%   *  DBT, A Matlab Toolbox for Radar Signal Processing  *
% (c) FOA 1994-2000. See the file dbtright.m for copyright notice.
%
%  function [sigOut] = cfar(sigIn)
%
%  Calculates the signals after CFAR.
%
%  sigOut (RxRadarSigT):
%  sigIn (RxRadarSigT):
%
%
%Known Bugs:

%
%  Start        : 961120 Fredrik Athley (freath).
%  Latest change: $Date: 2000/10/16 15:20:04 $ $Author: svabj $.
%  $Revision: 1.11 $
% *****************************************************************************

%ant = sigIn.antenna;
XX =  sigIn.signals;
s = sizem(XX);
N = 15;
noDopplerCh = s(1);
noRangeBins = s(2);
noBeams     = s(3);
noNotUsed   = s(4);
noCPIs      = s(5);
noTrials    = s(6);

if noRangeBins<3
  fprintf('\nWarning: Cannot perform CFAR. Too few range samples. Returning the signal unprocessed.\n\n')
  sigOut = sigIn;
else
  y = zeros(1,noRangeBins);		% Reserve memory space !?!
  YY = zerosm(s);

  for trialLoop = 1:noTrials
  for cpiLoop = 1:noCPIs
  for notUsedLoop = 1:noNotUsed
  for beam=1:noBeams
    for dopplerLoop=1:noDopplerCh
      x = getm(XX,dopplerLoop,':',beam,notUsedLoop,cpiLoop,trialLoop);
      x = reshape(x,1,noRangeBins);
      P = min(N+2,noRangeBins);
      for range=1:P
        Q = min(range+1+N,noRangeBins);

        %xr = [x(1:range-2) x(range+2:Q)];
        %meanxr = mean(xr);

        ixVec1 = 1:range-2;
        ixVec2 = range+2:Q;
        lengthSum = length(ixVec1) + length(ixVec2);
        meanxr2 = (1/lengthSum) * (sum(x(ixVec1))+sum(x(ixVec2)));
	meanxr = meanxr2;

        %if (abs(meanxr - meanxr2) > 1e-10)
        %  meanxr - meanxr2
 	%  error('Difference to large')
        %end%if

        y(range) = x(range)/meanxr;
        if (meanxr==0)
          %disp('Noise level = 0')
          dbtwarning('In "cfar", noise level = 0')
        end
      end
      for range=N+3:noRangeBins
        Q = min(range+1+N,noRangeBins);

        %xr = [x(range-1-N:range-2) x(range+2:Q)];
        %meanxr = mean(xr);

        ixVec1 = range-1-N:range-2;
        ixVec2 = range+2:Q;
        lengthSum = length(ixVec1) + length(ixVec2);
        meanxr2 = (1/lengthSum) * (sum(x(ixVec1))+sum(x(ixVec2)));
	meanxr = meanxr2;

        %difference = meanxr - meanxr2;
        %if (abs(difference) > 1e-10)
        %  meanxr - meanxr2
 	%  error('Difference to large')
        %end%if

        y(range) = x(range)/meanxr;
        if (meanxr==0)
          dbtwarning('In "cfar", noise level = 0')
          %disp('Noise level = 0')
        end
      end
      %YY = setm(YY,y,dopplerLoop,':',beam,notUsedLoop,cpiLoop,trialLoop);
      YY(dopplerLoop,':',beam,notUsedLoop,cpiLoop,trialLoop) = y;
    end%for dopplerLoop
    infoStr = sprintf('cfar: beam = %d(%d)\r',beam,noBeams);
    dbtinfo(infoStr,1);
  end%for beam
  dbtinfo('');	%New line.
  end%for notUsedLoop
  end%for cpiLoop
  end%for trialLoop

  sigOut = sigIn;  % Must copy all information in the input signal.
  sigOut.signals = YY; % Modify part of the input signal.

%  sigOut.dataType = 'RxRadarSigT';
%  sigOut.antenna = ant;
%  sigOut.signals = YY;
end%if