function[b,a]=afd_chb1(Omegap,Omegas,Ap,As)
% 切比雪夫I型模擬低通濾波器設(shè)計
% b=G(s)分子多項式的系數(shù)
% a=G(s)分母多項式的系數(shù)
% Omegap=通帶截止頻率，rad/s
% Omegap=阻帶截止頻率，rad/s
% Ap=通帶波動的+dB數(shù)
% As=阻帶波動的+dB數(shù)

if Omegap<=0
    error('通帶邊緣必須大于0')
end
if Omegas<=Omegap
    error('阻帶邊緣必須大于通帶邊緣')
end
if (Ap<=0)|(As<=0)
    error('通帶波動或阻帶衰減必須大于0')
end
ep=sqrt(10^(Ap/10)-1);
A=10^(As/20);
OmegaC=Omegap;
OmegaS=Omegas/Omegap;
g=sqrt(A*A-1)/ep;
N=ceil(log10(g+sqrt(g*g-1))/log10(OmegaS+sqrt(OmegaS*OmegaS-1)));
[b,a]=u_chb1ap(N,Ap,OmegaC);