%Cohere函數：計算兩序列的相干函數
NFFT=1024;
noverlap=512;
h=fir1(20,0.3,boxcar(21));
H=ones(1,10)/sqrt(10);
s=randn(16384,1);
x=filter(H,1,s);
y=filter(h,1,x);
cohere(x,y,NFFT,[],[],noverlap,'linear');