资源描述：
《小波变换程序》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。
1、小波滤波器构造和消噪程序（2个）1・重构%mallet_wavelet.m%此函数用于研究Mallet算法及滤波器设计%此函数仅用于消噪a=pi/8;%角度赋初值b二pi/&%低通重构FIR滤波器hO(n)冲激响应赋值hO=cos(a)*cos(b);hl=sin(a)*cos(b);h2=-sin(a)*sin(b);h3=cos^*sin(b);Iow_construct=[h0,hl,h2,h3];L_fre=4;%滤波器长度low_decompose=low_construct(end:-l:l);%确定hO(-n),低
2、通分解滤波器fori_high=l:L_fre;%确定hl(n)=(-l)An,itj通重建滤波器if(mod(i_high,2)==0);coefficient=-l;elsecoefficient=l;endhigh_construct(l,i_high)=low_decompose(l,i_high)*coefficient;endhigh_decompose=high_construct(end:-l:l);%高通分解滤波器hl(-n)L_signal=100;%信号长度n=l:L_signal;%信号赋值f=10;t=
3、0.001;y=10*cos(2*pi*50*n*t).*exp(-20*n*t);figure(l);Plot(y);title/原信号checkl=sum(high_decompose);%hO(n)性质校验check2=sum(low_decompose);check3二norm(high_decompose);check4=norm(low_decompose);l_fre=conv(y,low_decompose);%卷积l_fre_down=dyaddown(l_fre);%抽取，得低频细节h_fre=conv(y,
4、high_decompose);h_fre_down=dyaddown(h」re);%信号高频细ijfigure(2);subplot(2,l,l)plot(l_fre_down);titled小波分解的低频系数);subplot(2,l,2);plot(h_fre_down);title(小波分解的高频系数')；l_fre_pull=dyadup(l_fre_down);%0差值h_fre_pull=dyadup(h_fre_down);l_fre_denoise=conv(low_construct,l_fre_pull);
5、h_fre_denoise=conv(high_construct/h_fre_pull);l_fre_keep=wkeep(l_fre_denoise,L_signal);%取结果的中心部分,消除卷积影响h_fre_keep=wkeep(h_fre_denoise,L_signal);sig_denoise=l_fre_keep+h_fre_keep;%信号重构compare=sig_denoise-y;%与原信号比较figure(3);subplot(3,l,l)Plot(y);ylabel(V);%原信号subplot(3
6、,l,2);plot(sig_denoise);ylabel('sig_denoise');%重构信号subplot(3,l,3)；plot(compare);ylabelfcompare1);%原信号与消噪后信号的比较2.消噪%mallet_wavelet.m%此函数用于研究Mallet算法及滤波器设计%此函数用于消噪处理%角度赋值%此处赋值使滤波器系数恰为db9%分解的高频系数采用db9较好，即它的消失矩较大%分解的有用信号小波高频系数基木趋于零%对于噪声信号高频分解系数很大，便于阈值消噪处理[l,h]=wfilters(
7、'dblO',,d,);low_construct=l;L_fre=2O;%滤波器长度low_decompose=low_construct(end:-l:l);%确定hO(-n),低通分解滤波器fori_high=l:L_fre;%确定hl(n)=(-l)An,高通重建滤波器if(mod(i_high,2)==0);coefficient=-l;elsecoefficient二1;endhigh_construct(l,i_high)=low_decompose(lj_high)*coefficient;endhigh_dec
8、ompose=high_construct(end:-l:l);%高通分解滤波器hl(-n)L_signal=lOO;%信号长度n=l:L_signal;%原始信号赋值f=10;t=0.001;y=10*cos(2*pi*50*n*t).*exp(-30*n*t
