用matlab设计的IIR滤波器源程序-IIR一阶低通/高通

文章摘要：用matlab设计的IIR滤波器源程序（1）IIR一阶低通滤波器 P576clear;fi=1;fs=10;Gc2=0.9;wc=2*pi*fi/fs; omegac=tan(wc/2);alpha=(sqrt(Gc2)/sqrt(1-Gc2))*omegac;a=(1-alpha)/(1+alpha);b=(1-a)/2;w=0:pi/300:pi; Hw2=alpha^2./(alpha^2+(tan(w/2)).^2);plot(w/pi,Hw2);grid;hold on; （2）一阶高通滤波器 P581clear;fi=1;fs=10;Gc2=0.5;wc=2*p

用matlab设计的IIR滤波器源程序-IIR一阶低通/高通,标签：fpga是什么,fpga教程,http://www.88dzw.com

用matlab设计的IIR滤波器源程序

（1）IIR一阶低通滤波器 P576

clear;

fi=1;fs=10;Gc2=0.9;

wc=2*pi*fi/fs;     

omegac=tan(wc/2);

alpha=(sqrt(Gc2)/sqrt(1-Gc2))*omegac;

a=(1-alpha)/(1+alpha);

b=(1-a)/2;

w=0:pi/300:pi;     

Hw2=alpha^2./(alpha^2+(tan(w/2)).^2);

plot(w/pi,Hw2);

grid;

hold on;

 （2）一阶高通滤波器 P581

clear;

fi=1;fs=10;Gc2=0.5;

wc=2*pi*fi/fs;

omegac=tan(wc/2);

alpha=(sqrt(1-Gc2)/(sqrt(Gc2)))*omegac;

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;

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（Butterworth）

% IIR Lowpass Use Butterworth

% copyright by Etual

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);

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;

Hw2=1./(1+(tan(w/2)/omega0).^(2*N));

plot(w/pi,Hw2);

grid;

（6）IIR高通滤波（Butterworth）

% IIR Hightpass Use Butterworth

% copyright by Etual

clear;

fs=20;fpass=5;fstop=4;

Ap=0.5;As=10;

wp=2*pi*fpass/fs;ws=2*pi*fstop/fs;

omegap=cot(wp/2);omegas=cot(ws/2);

ep=sqrt(10^(Ap/10)-1);

es=sqrt(10^(As/10)-1);

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+eps):pi/300:pi;

Hw2=1./(1+(cot(w/2)/omega0).^(2*N));

plot(w/pi,Hw2);

grid;

（7）IIR带通滤波（Butterworth）

% IIR Bandpass Use Butterworth

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