atuocorrlation.m

自相关函数在噪声检测,识别和有用信号的提取中的应用

u=sqrt(1/exp(1.0));
v=u*randn(1,1000);
n=1:1000;w=1.4*pi;
xn=exp(j*pi*n-j*pi)+exp(j*w*n-j*0.7*pi)+v;
plot(n,xn);

m=-500:500;
[r,lag]=xcorr(xn,500,'biased');
hndl=stem(lag,r);
 set(hndl,'marker','o');
set(hndl,'MarkerSize',3);
xlabel('n');
title('atuocorrlation r')
% BT method
k=0:1000;
w=(pi/500)*k;
M=k/500;
x=r*(exp(-j*pi/500)).^(m'*k);
magx=abs(x);
plot(M,10*log10(magx));
xlabel('angular frequency,w');
ylabel('power spectrum magnitude(db)')
title('BT method');