MATLAB中一维小波变换的计算---以doppler信号为例

进行DWT的函数为： [C,L]=wavedec(x,N,'wname')

进行IDWT的函数为：x=waverec(C,L,'wname')

其中 wname为小波名；x为时域序列信号；N为小波变换的级数。

利用部分小波系数重建信号：x=wrcoef('type',C,L,'wname',N)

其中 type='a'为 由第N级近似分量重建信号

        type='d'为 由第N级细节分量重建信号

---

doppler = wnoise(4,10);

N = 5;

wname = 'db4';

[C,L] = wavedec(doppler,N,wname);

A0 = waverec(C,L,wname);

A5 = wrcoef('a',C,L,wname,5);

A4 = wrcoef('a',C,L,wname,4);

A3 = wrcoef('a',C,L,wname,3);

A2 = wrcoef('a',C,L,wname,2);

A1 = wrcoef('a',C,L,wname,1);

D5 = wrcoef('d',C,L,wname,5);

D4 = wrcoef('d',C,L,wname,4);

D3 = wrcoef('d',C,L,wname,3);

D2 = wrcoef('d',C,L,wname,2);

D1 = wrcoef('d',C,L,wname,1);

figure(1);

plot(doppler,'k','linewidth',2);

hold on;

plot(A0,'-.r','linewidth',2);

hold on;

plot(A5,'--b','linewidth',2);

legend('original doppler signal','IDWT signal----A0','level 5 approximation signal----A5');

axis([0 400 -1 1]);

set(gcf,'unit','centimeters','position',[10 10 30 10]);

figure(2);

subplot(3,2,1);

plot(doppler,'k','linewidth',2);

title('doppler signal');

axis([0 400 -1 1]);

subplot(3,2,2);

plot(D5,'k','linewidth',2);

title('D5 detail of db4');

axis([0 400 -1 1]);

subplot(3,2,3);

plot(D4,'k','linewidth',2);

title('D4 detail of db4');

axis([0 400 -1 1]);

subplot(3,2,4);

plot(D3,'k','linewidth',2);

title('D3 detail of db4');

axis([0 400 -1 1]);

subplot(3,2,5);

plot(D2,'k','linewidth',2);

title('D2 detail of db4');

axis([0 400 -1 1]);

subplot(3,2,6);

plot(D1,'k','linewidth',2);

title('D1 detail of db4');

axis([0 400 -1 1]);

figure(3);

subplot(3,2,1);

plot(doppler,'r','linewidth',2);

title('doppler signal');

axis([0 400 -1 1]);

subplot(3,2,2);

plot(A5,'r','linewidth',2);

title('A5 approximation');

axis([0 400 -1 1]);

subplot(3,2,3);

plot(A4,'r','linewidth',2);

title('A4 approximation');

axis([0 400 -1 1]);

subplot(3,2,4);

plot(A3,'r','linewidth',2);

title('A3 approximation');

axis([0 400 -1 1]);

subplot(3,2,5);

plot(A2,'r','linewidth',2);

title('A2 approximation');

axis([0 400 -1 1]);

subplot(3,2,6);

plot(A1,'r','linewidth',2);

title('A1 approximation');

axis([0 400 -1 1]);