function [b,a]=afd_chb2(Wp,Ws,Rp,As);
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 ust be larger than 0')
end
ep=sqrt(10^(Rp/10)-1);
A=10^(As/20);
OmegaC=Wp;
OmegaR=Ws/Wp;
g=sqrt(A*A-1)/ep;
N=ceil(log10(g+sqrt(g*g-1))/log10(OmegaR+sqrt(OmegaR*OmegaR-1)));
fprintf('\n***Chebyshev-2 Filer Order=%2.0f\n',N)
[b,a]=u_chb2ap(N,As,Ws);