IIR滤波器matlab源程序

1 IIR 滤波器matlab 源程序 （1）IIR 一阶低通滤波器 clear; fi=1;fs=10;Gc2=0.9; w c=2*pi*fi/fs; omegac=tan(w c/2); alpha=(sqrt(Gc2)/sqrt(1-Gc2))*omegac; a=(1-alpha)/(1+alpha); b=(1-a)/2; w =0:pi/300:pi; Hw 2=alpha^2./(alpha^2+(tan(w /2)).^2); plot(w /pi,Hw 2); grid; hold on; （2）一阶高通滤波器 clear; fi=1;fs=10;Gc2=0.5; w c=2*pi*fi/fs; omegac=tan(w c/2); alpha=(sqrt(1-Gc2)/(sqrt(Gc2)))*omegac; 2 a=(1-alpha)/(1+alpha); b=(1+a)/2; w=0:pi/300:pi; Hw2=(tan(w/2).^2)./(alpha^2+(tan(w/2)).^2); plot(w/pi,Hw2); grid; hold on; （3）Notch 嵌波滤波器 clear; Gb2=0.5; w0=0.35*pi; deltaw=0.1*pi; b=1/(1+tan(deltaw/2)*(sqrt(1-Gb2)/sqrt(Gb2))); B=[1 -2*cos(w0) 1].*b; A=[1 -2*b*cos(w0) (2*b-1)]; w=0:pi/500:pi; H=freqz(B,A,w); plot(w/pi,abs(H)); grid; （4）Peak 滤波器 clear; 3 Ac=3; Gb2=10^(-Ac/10); w0=0.35*pi; deltaw=0.1*pi; b=1/(1+tan(deltaw/2)*(sqrt(Gb2)/sqrt(1-Gb2))); B=[1 0 -1].*(1-b); A=[1 -2*b*cos(w0) (2*b-1)]; w=0:pi/500:pi; H=freqz(B,A,w); plot(w/pi,abs(H)); grid; （5）IIR 低通滤波（Butterw orth） % IIR Lowpass Use Butterworth clear; fs=20;fpass=4;fstop=5; Ap=0.5;As=10; wp=2*pi*fpass/fs;ws=2*pi*fstop/fs; omegap=tan(wp/2);omegas=tan(ws/2); ep=sqrt(10^(Ap/10)-1); es=sqrt(10^(As/10)-1); 4 N=ceil(log(es/ep)/log(omegas/omegap)); omega0=omegap/ep^(1/N); K=floor(N/2); for i=1:K theta(i)=pi*(N-1+2*i)/(2*N); end for i=1:K G(i)=omega0^2/(1-2*omega0*cos(theta(i))+omega0^2); end for i=1:K a1(i)=2*(omega0^2-1)/(1-2*omega0*cos(theta(i))+omega0^2); end for i=1:K a2(i)=(1+2*omega0*cos(theta(i))+omega0^2)/(1-2*omega0*cos(theta(i))+omega0^2); end if K<(N/2) G0=omega0/(omega0+1);a0=(omega0-1)/(omega0+1); end w =0:pi/300:pi; Hw 2=1./(1+(tan(w /2)/omega0).^(2*N)); plot(w /pi,Hw 2); grid; 5 （6）IIR 高通滤波（Butterw orth） % IIR Hightpass Use Butterw orth clear; fs=20;fpass=5;fstop=4; Ap=0.5;As=10; w p=2*pi*fpass/fs;w s=2*pi*fstop/fs; omegap=cot(w p/2);om...