用matlab设计的IIR滤波器源程序-IIR一阶低通/高通

文章摘要：% copyright by Etualclear;fs=20;fpa=2;fpb=4;fsa=1.5;fsb=4.5;Ap=0.0877;As=16.9897;wpa=2*pi*fpa/fs;wpb=2*pi*fpb/fs;wsa=2*pi*fsa/fs;wsb=2*pi*fsb/fs;c=sin(wpa+wpb)/(sin(wpa)+sin(wpb));omegap=abs((c-cos(wpb))/sin(wpb));omegasa=(c-cos(wsa))/sin(wsa);omegasb=(c-cos(wsb))/sin(wsb);omegas=min(abs(omegasa),ab

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

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clear;

fs=20;fpa=2;fpb=4;fsa=1.5;fsb=4.5;

Ap=0.0877;As=16.9897;

wpa=2*pi*fpa/fs;wpb=2*pi*fpb/fs;wsa=2*pi*fsa/fs;wsb=2*pi*fsb/fs;

c=sin(wpa+wpb)/(sin(wpa)+sin(wpb));

omegap=abs((c-cos(wpb))/sin(wpb));

omegasa=(c-cos(wsa))/sin(wsa);omegasb=(c-cos(wsb))/sin(wsb);

omegas=min(abs(omegasa),abs(omegasb));

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)=4*c*(omega0*cos(theta(i))-1)/(1-2*omega0*cos(theta(i))+omega0^2);

end

for i=1:K

    a2(i)=2*(2*c^2+1-omega0^2)/(1-2*omega0*cos(theta(i))+omega0^2);

end

for i=1:K

    a3(i)=-(4*c*(omega0*cos(theta(i))+1))/(1-2*omega0*cos(theta(i))+omega0^2);

end

for i=1:K

    a4(i)=(1+2*omega0*cos(theta(i))+omega0^2)/(1-2*omega0*cos(theta(i))+omega0^2);

end

if K<(N/2)

    G0=omega0/(1+omega0);a0(1)=-2*c/(1+omega0);a0(2)=(1-omega0)/(1+omega0);

end

w=(0+eps):pi/300:pi;

Hw2=1./(1+((c-cos(w))./(omega0*sin(w))).^(2*N));

plot(w/pi,Hw2);

grid;

（8）IIR带阻滤波（Butterworth）

% IIR Bandstop Use Butterworth

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clear;

fs=20;fpa=1.5;fpb=4.5;fsa=2;fsb=4;

Ap=0.5;As=10;

wpa=2*pi*fpa/fs;wpb=2*pi*fpb/fs;wsa=2*pi*fsa/fs;wsb=2*pi*fsb/fs;

c=sin(wpa+wpb)/(sin(wpa)+sin(wpb));

omegap=abs(sin(wpb)/(c-cos(wpb)));

omegasa=sin(wsa)/(cos(wsa)-c);omegasb=sin(wsb)/(cos(wsb)-c);

omegas=min(abs(omegasa),abs(omegasb));

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);

theta=zeros(1,K);

for i=1:K

    theta(i)=pi*(N-1+2*i)/(2*N);

end

G=zeros(1,K);a1=zeros(1,K);a2=zeros(1,K);

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+(sin(w)./(omega0*(c-cos(w)))).^(2*N));

plot(w/pi,Hw2);

grid;

（9）IIR低通滤波（chebyshev 1）

% IIR Lowpass Use Chebyshev Type 1

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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);

e=es/ep;w=omegas/omegap;

N=ceil(log(e+sqrt(e^2-1))/log(w+sqrt(w^2-1)));

a=log(1/ep+sqrt(1/ep^2+1))/N;

omega0=omegap*sinh(a);

K=floor(N/2);

theta=zeros(1,K);omega=zeros(1,K);

for i=1:K

    theta(i)=pi*(N-1+2*i)/(2*N);

end

for i=1:K

    omega(i)=omegap*sin(theta(i));

end

G=zeros(1,K);a1=zeros(1,K);a2=zeros(1,K);

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