u_chb1ap.m

Digital signal processing using Matlab一書之範例程式

function [b,a] = u_chb1ap(N,Rp,Omegac);
% Unnormalized Chebyshev-1 Analog Lowpass Filter Prototype
% --------------------------------------------------------
% [b,a] = u_chb1ap(N,Rp,Omegac);
%      b = numerator polynomial coefficients
%      a = denominator polynomial coefficients
%      N = Order of the Elliptic Filter
%     Rp = Passband Ripple in dB; Rp > 0
% Omegac = Cutoff frequency in radians/sec
%
[z,p,k] = cheb1ap(N,Rp);
      a = real(poly(p));
    aNn = a(N+1);
      p = p*Omegac;
      a = real(poly(p));
    aNu = a(N+1);  
      k = k*aNu/aNn;
      b0 = k;
      B = real(poly(z));
      b = k*B;