afd_elip.m

the file contain many matlab signal source code and many example .

function [b,a]=afd_elip(Wp,Ws,Rp,As);
% Analog Lowpass Filter Design:Elliptic
% -------------------------
% [b,a]=afd_elip(Wp,Ws,Rp,As)
% b=Numberator coefficients of Ha(s)
% a=Denominator coefficients of Ha(s)
% Wp=Passband edge frequency in rad/sec;Wp>0
% Ws=Stopband edge frequency in rad/sec;Ws>Wp>0
% Rp=Passband ripple in +dB;(Rp>0)
% As=Stopband attenuation in +dB;(As>0)
% 
if Wp<=0
    error('Passband edge must be larger than 0')
end
if Ws<=Wp
    error ('Stopband edge must be larger than Passband edge')
end
if (Rp<=0)|(As<0)
    error('PB ripple and/or SB attenuation must be larger than 0')
end
ep=sqrt(10^(Rp/10)-1);
A=10^(As/20);
OmegaC=Wp;
k=Wp/Ws;
k1=ep/sqrt(A*A-1);
capk=ellipke([k.^2 1-k.^2]);
capk1=ellipke([k1.^2 1-k1.^2]);
N=ceil(capk(1)*capk1(2)/(capk(2)*capk1(1)));
fprintf('\n* * * Elliptic Filter Order=%2. of \n',N)
[b,a]=u_elipap(N,Rp,As,OmegaC);