1 ## Copyright (C) 2007 Sylvain Pelissier <sylvain.pelissier@gmail.com>
3 ## This program is free software; you can redistribute it and/or modify it under
4 ## the terms of the GNU General Public License as published by the Free Software
5 ## Foundation; either version 3 of the License, or (at your option) any later
8 ## This program is distributed in the hope that it will be useful, but WITHOUT
9 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 ## You should have received a copy of the GNU General Public License along with
14 ## this program; if not, see <http://www.gnu.org/licenses/>.
17 ## @deftypefn {Function File} {[@var{m}] =} amdemod (@var{s}, @var{fc}, @var{fs})
18 ## Compute the amplitude demodulation of the signal @var{s} with a carrier
19 ## frequency of @var{fc} and a sample frequency of @var{fs}.
23 function [m] = amdemod(s,fc,fs)
25 usage("m = amdemod(s,fc,fs)");
27 t = 0:1./fs:(length(s)-1)./fs;
28 e = s.*cos(2.*pi.*fc.*t);
29 [b a] = butter(5,fc.*2./fs);
30 m = filtfilt(b,a,e).*2;