youfa.asv

对指数式衰减的加油噪声的信号(诱发响应)提取,噪声越小,提取出的信号越接近原信号

fs=1000;
f=20;
M=0.5;
t=0:1/fs:M;
n=length(t);
s=sin(2*pi*f*t).*exp(-20*t); %st诱发响应：指数衰减正弦波
%plot(s);
N=1000;
xt=zeros(N,n);
for i=1:N
    e=rand(1,n);
    a=rand(1,1)/20;
    h=zeros(1,floor(a*fs));%潜伏期长度
    x=s+e;
    xt(i,:)=[h x(1:n-length(h))];%xt观测值:诱发响应+自发响应
end;
%plot(xt(1,:);
S=mean(xt);
R=zeros(N,2*n-1);
for i=1:N
    R(i,:)=xcorr(S,xt(i,:));%R表示求St与xt的互相关
end;
plot(R(1,:));
[m,ho]=max(R');
zyc=min(ho);
C=zeros(1,N);
w=zeros(N,n);
for i=1:N
    C(i)=ho(i)-c+1;
    B=zeros(1,C(i));
    w(i,:)=[y(i,C(i)+1:n) B];
end 
W=mean(w);
subplot(211);plot(w(1,:));
subplot(212);plot(W);