DOC《一、课程设计题目》

,'

FIR高通'

,'

FIR带通'

);

if k1==1 firlowpass;

else if k1==2 firhighpass;

else if k1==3 firbandpass;

end end end else if k==2 k2=menu('

请选择IIR滤波器类型:'

,'

IIR低通'

,'

IIR高通'

,'

IIR带通'

);

if k2==1 iirlowpass;

else if k2==2 iirhighpass;

else if k2==3 iirbandpass;

end end end end end b=menu('

do you want to continue?'

,'

yes'

,'

no'

);

if b==2 b=0;

end end temp=1;

temp=menu('

close all figure?'

,'

yes'

,'

no'

);

if temp==1 close all end 2.子程序: (!)、FIR低通滤波器: function[]= firlowpass();

[y,fs,bit]=wavread('

yuyin.wav'

) N=length(y);

%返回采样点数 t=(1:N)/fs;

df=fs/N;

%采样间隔 n1=1:N;

f=(n1-1)*df;

%频带宽度 wp=2*pi*1000/fs;

ws=2*pi*1200/fs;

width=ws-wp n=ceil(12.8*pi/width)+1 wn=(ws+wp)/2 beta=10.056 win=kaiser(n,beta) b=fir1(n-1,wn/pi,win) [H,m]=freqz(b,[1],1024,'

whole'

) figure(1) plot(m,abs(H)) title('

FIR数字低通滤波器幅度响应'

) figure(2) subplot(2,1,1) plot(t,y) title('

声音信号时域波形'

) c=fftfilt(b,y) subplot(2,1,2) plot(t,c) title('

过滤后声音信号时域波形'

) figure(3) y1=fft(y) subplot(2,1,1) plot(f,abs(y1)) title('

声音信号幅度响应'

) c1=fft(c) subplot(2,1,2) plot(f,abs(c1)) title('

过滤后声音信号幅度响应'

) sound(c,fs) 实验结果: (2)、FIR低通滤波器: function[]=firhighpass();

[y,fs,bit]=wavread('

yuyin.wav'

) N=length(y);

%返回采样点数 t=(1:N)/fs;

df=fs/N;

%采样间隔 n1=1:N;

f=(n1-1)*df;

%频带宽度 wp=2*pi*5000/fs;

ws=2*pi*4800/fs;

width=wp-ws n=ceil(12.8*pi/width)+1 wn=(ws+wp)/2 beta=10.056 b=fir1(n-1,wn/pi,'

high'

,kaiser(n,beta)) [H,m]=freqz(b,[1],1024,'

whole'

) figure(1) plot(m,abs(H)) title('

FIR数字高通滤波器幅度响应'

) figure(2) subplot(2,1,1) plot(t,y) title('

声音信号时域波形'

) c=fftfilt(b,y) subplot(2,1,2) plot(t,c) title('

过滤后声音信号时域波形'

) sound(c,fs) y1=fft(y) c1=fft(c) figure(3) subplot(2,1,1) plot(f,abs(y1)) title('

声音信号幅度响应'

) subplot(2,1,2) plot(f,abs(c1)) title('

过滤后声音信号幅度响应'

) sound(c,fs) 实验结果: (3)、FIR带通滤波器: function[]=firbandpass();

[y,fs,bit]=wavread('

yuyin.wav'

) N=length(y);

%返回采样点数 t=(1:N)/fs;

df=fs/N;

%采样间隔 n1=1:N;

f=(n1-1)*df;

%频带宽度 wp=[2*pi*1200/fs,2*pi*3000/fs] ws=[2*pi*1000/fs,2*pi*3200/fs] width=2*pi*1200/fs-2*pi*1000/fs n=ceil(12.8*pi/width)+1 wn=(ws+wp)/2 beta=10.056 win=kaiser(n,beta) b=fir1(n-1,wn/pi,win) [H,m]=freqz(b,[1],200,'

whole'

) figure(1) plot(m,abs(H)) title('

FIR数字带通滤波器幅度响应'

) figure(2) subplot(2,1,1) plot(t,y) title('

声音信号时域波形'

) c=fftfilt(b,y) subplot(2,1,2) plot(t,c) title('

过滤后声音信号时域波形'

) y1=fft(y) c1=fft(c) figure(3) subplot(2,1,1) plot(f,abs(y1)) title('

声音信号幅度响应'

) subplot(2,1,2) plot(f,abs(c1)) title('

过滤后声音信号幅度响应'

) sound(c,fs) 实验结果: (4)、IIR低通滤波器: function[]=iirlowpass();

[x,fs,bits]=wavread('

yuyin.wav'

);

%播放原始信号 N=length(x);