实验四IIR数字滤波器设计及软件实现实验报告

pace(0,pi,1000) ;Рh = freqz(bLPz,aLPz ,w) ;Рsubplot(2,1,2),plot(w*Fs/2/pi,20*log10(abs(h)) ) ;Рaxis([0 1600 -80 5]),gridРtitle('数字低通滤波器的幅度特性');Рxlabel('f(Hz)' ) ;Рylabel('dB' ) ;Р%%3.2a 设计模拟带通滤波器Рfp=[430 570];fs=[330 670];Ap=0.1;As=60;Рwp=2*pi*fp/Fs;ws=2*pi*fs/Fs;РWp=(2*Fs)*tan(wp/2);Ws=(2*Fs)*tan(ws/2);Р[N,Wc]= ellipord(Wp ,Ws ,Ap ,As ,'s');Р[bBPs ,aBPs]=ellip(N ,Ap,As,Wc,'s') ;Р[H,w]=freqs(bBPs,aBPs);Рdb =20*log10(abs(H));Рfigure,subplot(2,1,1),plot(w/2/pi,db);Рaxis([0 1600 -80 5]),gridРtitle('模拟带通滤波器的幅度特性');Рxlabel('f(Hz)');Рylabel('dB')Р%%3.2b 将模拟带通滤波器转换为数字带通滤波器Р[bBPz,aBPz] = bilinear(bBPs ,aBPs ,Fs) ;Рw = linspace(0,pi,1000) ;Рh = freqz(bBPz,aBPz ,w) ;Рsubplot(2,1,2),plot(w*Fs/2/pi,20*log10(abs(h)) ) ;Рaxis([0 1600 -80 5]),gridРtitle('数字低通滤波器的幅度特性');Рxlabel('f(Hz)' ) ;Рylabel('dB' ) ;