adaptive filter (in series).m

提供一种新型自适应滤波器的设计方法

% 功能：自适应滤波器(串联)             
% 作者：liukai
% 日期:2008年6月12日
% 状态:调试完成
%-------------------------------------------------------------------------%
% function ad1
clear all,close all
fs=200;
t1=0:1/fs:25;
dn1=randn(size(t1));
t2=0:1/fs:5;
dn2=2*sin(2*pi*40*t2);
t3=0:1/fs:5;
dn3=2*sin(2*pi*50*t3);
dn=zeros(size(t1));
dn(1000:(length(t2)+999))=dn2;
dn((length(t2)+999+1000):(length(t3)+length(t2)+999+999))=dn3;
dn=dn+dn1;
t=t1;
figure
subplot(3,1,1)
plot(t,dn);
% D=fft(dn,2048);
% wd=(0:1023)*fs/2048;
% figure
% plot(wd,abs(D(1:1024)));
% axis([0 8000 -100 1000]);
xn1=sin(2*pi*40*t);
xn2=cos(2*pi*40*t);
wn1=zeros(size(t));
wn2=zeros(size(t));
yn=zeros(size(t));
en=zeros(size(t));
u=1/100;
en(1)=dn(1)-yn(1);
wn1(1)=2*u*en(1)*xn1(1);
wn2(1)=2*u*en(1)*xn2(1);
for i=1:length(t)-1
    yn(i)=xn1(i)*wn1(i)+xn2(i)*wn2(i);
    en(i)=dn(i)-yn(i);
    wn1(i+1)=wn1(i)+2*u*en(i)*xn1(i);
    wn2(i+1)=wn2(i)+2*u*en(i)*xn2(i);
end 
subplot(3,1,2)
plot(t,yn);
Y=fft(yn,4096);
w=(0:2047)*fs/4096;
subplot(3,1,3)
plot(w,abs(Y(1:2048)));
dnn=en;
% figure(4)
% plot(t,dnn);
% DN=fft(dnn,4096);
% w1=(0:2047)*fs/4096;
% figure(5)
% plot(w1,abs(DN(1:2048)));
% ----------------下一级---------------------------------------
xn3=sin(2*pi*50*t);
xn4=cos(2*pi*50*t);
wn3=zeros(size(t));
wn4=zeros(size(t));
ynn=zeros(size(t));
enn=zeros(size(t));
for i=1:length(t)-1
    ynn(i)=xn3(i)*wn3(i)+xn4(i)*wn4(i);
    enn(i)=dnn(i)-ynn(i);
    wn3(i+1)=wn3(i)+2*u*enn(i)*xn3(i);
    wn4(i+1)=wn4(i)+2*u*enn(i)*xn4(i);
end 
figure(3)
subplot(3,1,1)
plot(ynn);
YN=fft(ynn,4096);
wn=(0:2047)*fs/4096;
subplot(3,1,2)
plot(wn,abs(YN(1:2048)));
subplot(3,1,3)
plot(t,enn);