%Digital Filter Specifications:
wp=0.2*pi;          %       digital Passband freq in rad 
ws=0.3*pi;          %       digital Stopband freq in rad
Rp=1;               %       Passband ripple in dB
As=15;              %       Stopband attenuation in dB
% Analog Prototype Specifications:Inverse mapping for frequencies
T=1;                %        Set T=1
OmegaP=wp/T;        %        Prototype Passband freq
OmegaS=ws/T;        %        Prototype Stopband freq
% Analog Chebyshev-1 Prototype Filter Calculation:
[cs,ds]=afd_chb2(OmegaP,OmegaS,Rp,As);
% ***Chebyshev-2 Filter Order=4
% Impulse Invariance transformation:
[b,a]=imp_invr(cs,ds,T);
[C,B,A]=dir2par(b,a)