afd_chb2.m

很多matlab的源代码

function [b,a] = afd_chb2(Wp,Ws,Rp,As)
% Analog Lowpass Filter Design:Chebyshev-2
% -------------------------------------------
% [b,a] = afd_chb2(Wp,Ws,Rp,As);
% b = Numerator coefficients of Ha(s)
% a = Denomintor 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 large 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 Filter ORder = % 2.of\n',N)
[b,a] = u_chb2ap(N,As,Ws);