afdnbut.m

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

function nbut = afdnbut(Fp,Fs,Kp,Ks)

% afdnbut.m  AFD minimum Butterworth order
%
% 16:44  17/2/99
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.02.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/02/08 03:07:42 $
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica

k    = Fp/Fs;
L    = Ks/Kp;
num  = log10(L);
den  = log10(1/k);
nbut = ceil(num/den);