autocorrelationwin.m

calculation of the autocorrelation peak sidelobe levels and corsscorrelation. CE sequence, frank aut

function [x,nfft]=autocorrelationwin(L,S,winid)

% m=power_integer_2(L);
% nfft=2^(m);
nfft=2*L-1;

S=[S, zeros(1,(nfft-L))];
if (winid==0.)
    win(1:nfft)=1.;
    win=win';
else 
    if (winid==1.)
        win=hamming(nfft);
    else
        if(winid==2.)
            win=kaiser(nfft,pi);
        else
            if(winid==3.)
                win=hann(nfft);
            end
        end
    end
end
       

col=0;
for fdT=0:.01:2
   col=col+1;
   for row=1:nfft
      Sr(row)=S(row)*exp(i*2.*pi*(row-1)*fdT/L);
   end
   x(col,:) = fftshift(abs(ifft(fft(Sr).* conj(fft(S)).*win'))/L);
end

% % test if the autocorrelation figure in the fdT=0 right matched the former Ac computered   
% figure(1);
% time=(-(nfft/2)):1:(nfft/2-1);
% plot(time,Ac);
% hold all
% plot(time,x(:,21),'--r');

% time=(-(nfft/2)):1:(nfft/2-1);
% fdT=-2:.1:2;
% % box off;
% figure(1);
% mesh(time,fdT,x);
% xlabel('sample shift');
% ylabel('Doppler shift fd*T');
% zlabel('Autocorrelation function');
% 
% figure(2);
% contour(time,fdT,x);
% xlabel('sample shift');
% ylabel('Doppler shift fd*T');