基于MATLAB的数字信号处理-巴特沃斯和切比雪夫滤波器的设计

%设计IIR数字巴特沃斯低通滤波器
Wp=0.2;Ws=0.35;Rp=1;Rs=8;
[N,Wc]=buttord(Wp,Ws,Rp,Rs);
[Bz,Az]=butter(N,Wc);
w=0:0.01:pi;[H,w]=freqz(Bz,Az,w);
subplot(1,2,1),plot(w/pi,20*log10(abs(H))),grid on
title('幅频特性曲线');xlabel('\omega/\pi');ylabel('|H(e^j^\omega)|(dB)')
subplot(1,2,2),plot(w/pi,angle(H)/pi);
title('相频特性曲线');xlabel('\omega/\pi');ylabel('\phi(\omega)/\pi')

%设计IIR数字巴特沃斯高通滤波器
Wp=0.35;Ws=0.2;Rp=1;Rs=8;
[N,Wc]=buttord(Wp,Ws,Rp,Rs);
[Bz,Az]=butter(N,Wc,'high');
w=0:0.01:pi;[H,w]=freqz(Bz,Az,w);
subplot(1,2,1),plot(w/pi,20*log10(abs(H))),grid on
title('幅频特性曲线');xlabel('\omega/\pi');ylabel('|H(e^j^\omega)|(dB)')
subplot(1,2,2),plot(w/pi,angle(H)/pi);
title('相频特性曲线');xlabel('\omega/\pi');ylabel('\phi(\omega)/\pi')

%设计IIR数字巴特沃斯带通滤波器
Wp=[0.2,0.3];Ws=[0.1,0.4];Rp=1;Rs=8;
[N,Wc]=buttord(Wp,Ws,Rp,Rs);
[Bz,Az]=butter(N,Wc);
w=0:0.01:pi;[H,w]=freqz(Bz,Az,w);
subplot(1,2,1),plot(w/pi,20*log10(abs(H))),grid on
title('幅频特性曲线');xlabel('\omega/\pi');ylabel('|H(e^j^\omega)|(dB)')
subplot(1,2,2),plot(w/pi,angle(H)/pi);
title('相频特性曲线');xlabel('\omega/\pi');ylabel('\phi(\omega)/\pi')