N=2048;
w1=1;w2=1.3;phi1=-pi/3;phi2=pi/4;
s1=randn（N1）;s2=sqrt（0.9）*randn（N1）;
n=[0:N-1]‘;
xn=s1.*cos（w1*n+phi1）+s2.*cos（w2*n+phi2）;
XW1=fftshift（fft（xn））/N;
XW2=fftshift（fft（xn