clear?all
N=256;???????????????????????????????%觀測(cè)樣本個(gè)數(shù)??????????????????
noise=sqrt（0.01）*（（randn（1N）+1i*randn（1N））/sqrt（2））;
?????????????????????????????????????%噪聲信號(hào)
f1=0.1;??????????????????????????????%信號(hào)歸一化頻率
f2=0.25;
f3=0.27;
A1=1;????????????????????????????????%信號(hào)幅度???
A2=1;
A3=0.5;
signal1=A1*exp（1i*2*pi*f1*（0:N-1））;??%有用信號(hào)
signal2=A2*exp（1i*2*pi*f2*（0:N-1））;
signal3=A3*exp（1i*2*pi*f3*（0:N-1））;
xn=signal1+signal2+signal3+noise;????%帶噪信號(hào)
M=8;?????????????????????????????????%濾波器階數(shù)
for?k=1:N-M??????????????????????????
xs（:k）=xn（k+M