dfdrx.m

AFD - Advanced Filter Design using MATLABMiroslav D. Lutovac, Dejan V. Tosicversion 1.00 released 15

function Rx = dfdrx(c)

% dfdrx.m  DFD Rx(c)
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.03.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/03/08 03:07:42 $
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica

%  calls:
%% dfdxna.m

global DFD_n_x_Ks_Kp;
nxkskp = DFD_n_x_Ks_Kp;
n  = nxkskp(1);
x  = nxkskp(2);
Ks = nxkskp(3);
Kp = nxkskp(4);

a=1+c^2;

X = zeros(1,n);
for i =1:n
  X(i) = ellipj( ((2*i-1)/n + 1)*ellipke(1/a^2), 1/a^2);
end

X = dfdxna(n,a);

r = 1; R = ones(size(x));
if abs(n-2*fix(n/2)) == 0
  for i=1:n/2
    r = r * ((1 - X(i)^2))/((1 - a^2/X(i)^2));
    R = R .* ((x.^2 - X(i)^2))./((x.^2 - a^2/X(i)^2));
  end
else
  for i=1:(n-1)/2
    r = r * ((1 - X(i)^2))/((1 - a^2/X(i)^2));
    R = R .* ((x.^2 - X(i)^2))./((x.^2 - a^2/X(i)^2));
  end
    R = x .* R;
end
Rx = (R/r - Ks/Kp)^2;