用matlab设计的IIR滤波器源程序-IIR一阶低通/高通

文章摘要：for i=1:K G(i)=(omega0^2+omega(i)^2)/(1-2*omega0*cos(theta(i))+omega0^2+omega(i)^2);endfor i=1:K a1(i)=2*(omega0^2+omega(i)^2-1)/(1-2*omega0*cos(theta(i))+omega0^2+omega(i)^2);endfor i=1:K a2(i)=(1+2*omega0*cos(theta(i))+omega0^2+omega(i)^2)/(1-2*omega0*cos(theta(i))+omega0^2+omega(i)^2);en

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

for i=1:K

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

end

for i=1:K

    a1(i)=2*(omega0^2+omega(i)^2-1)/(1-2*omega0*cos(theta(i))+omega0^2+omega(i)^2);

end

for i=1:K

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

end

if K<(N/2)

    G0=omega0/(omega0+1);a0=(omega0-1)/(omega0+1);  

else

    H0=sqrt(1/(1+ep^2));

end

f=0:1/300:10;

Hf2=1./(1+ep^2*(cheby(N,tan(pi*f/fs)/omegap)).^2);

plot(f,abs(Hf2));

grid;

 （9）IIR低通滤波（chebyshev 1）

% IIR Lowpass Use Chebyshev Type 2

% 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);

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

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

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

omega0=omegas/sinh(a);

K=floor(N/2);

for i=1:K

    theta(i)=pi*(N-1+2*i)/(2*N);

end

for i=1:K

    omega(i)=omegas/sin(theta(i));

end

for i=1:K

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

end

for i=1:K

    a1(i)=2*(1-omega0^-2+omega(i)^-2)/(1-2*omega0^-1*cos(theta(i))+omega0^-2+omega(i)^-2);

end

for i=1:K

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

end

for i=1:K

    b1(i)=2*(1-omega(i))/(1+omega(i));

end

if K<(N/2)

    G0=omega0/(omega0+1);a0=(omega0-1)/(omega0+1);  

else

    H0=sqrt(1/(1+ep^2));

end

f=(0+eps):1/100:10;

Hf2=(cheby(N,omegas./tan(pi*f/fs))).^2./((cheby(N,omegas./tan(pi*f/fs))).^2+es^2);

plot(f,abs(Hf2));

grid;

（10）chebyshev 中用到的函数 cheby.m

function CN=cheby(N,x)

if x<=1

    CN=cos(N*acos(x));

else

    CN=cosh(N*log(x+sqrt(x.^2-1)));

end

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