examp16_2.m

《小波分析理论与Matlab7实现例程》一书里面各章节的源码

%生成含噪正弦信号
N=1024;
t=1:N;
sig=sin(0.03*t);
figure(1);
plot(t,sig,'LineWidth',2);xlabel('时间 t/s');ylabel('幅值 A');
%叠加信号
x=sig+randn(1,N);
x1=wextend(1,'ppd',x,20);
N1=N+2*20;
t1=1:N1;
figure(2)
subplot(211);plot(t,x,'LineWidth',2);title('原始信号');xlabel('时间 t/s');ylabel('幅值 A');
subplot(212);plot(t1,x1,'linewidth',2);title('延拓信号');xlabel('时间 t/s');ylabel('幅值 A');
%一维小波分解
[c,l] = wavedec(x1,5,'db5');
%重构第1～5层逼近信号
a5 = wrcoef('a',c,l,'db5',5);
a4 = wrcoef('a',c,l,'db5',4);
a3 = wrcoef('a',c,l,'db5',3);
a2 = wrcoef('a',c,l,'db5',2);
a1 = wrcoef('a',c,l,'db5',1);
%显示各层逼近信号
figure(3)
subplot(5,1,1);plot(a5,'LineWidth',2);ylabel('a5');
subplot(5,1,2);plot(a4,'LineWidth',2);ylabel('a4');
subplot(5,1,3);plot(a3,'LineWidth',2);ylabel('a3');
subplot(5,1,4);plot(a2,'LineWidth',2);ylabel('a2');
subplot(5,1,5);plot(a1,'LineWidth',2);ylabel('a1');
xlabel('时间 t/s');
%重构第1～5层细节信号
d5 = wrcoef('d',c,l,'db5',5);
d4 = wrcoef('d',c,l,'db5',4);
d3 = wrcoef('d',c,l,'db5',3);
d2 = wrcoef('d',c,l,'db5',2);
d1 = wrcoef('d',c,l,'db5',1);
%显示各层细节信号
figure(4)
subplot(5,1,1);plot(d5,'LineWidth',2);ylabel('d5');
subplot(5,1,2);plot(d4,'LineWidth',2);ylabel('d4');
subplot(5,1,3);plot(d3,'LineWidth',2);ylabel('d3');
subplot(5,1,4);plot(d2,'LineWidth',2);ylabel('d2');
subplot(5,1,5);plot(d1,'LineWidth',2);ylabel('d1');
xlabel('时间 t/s');