Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / communications-1.1.1 / amdemod.m

diff --git a/octave_packages/communications-1.1.1/amdemod.m b/octave_packages/communications-1.1.1/amdemod.m
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+## Copyright (C) 2007 Sylvain Pelissier <sylvain.pelissier@gmail.com>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{m}] =} amdemod (@var{s}, @var{fc}, @var{fs})
+## Compute the amplitude demodulation of the signal @var{s} with a carrier 
+## frequency of @var{fc} and a sample frequency of @var{fs}.
+## @seealso{ammod}
+## @end deftypefn
+
+function [m] = amdemod(s,fc,fs)
+  if(nargin ~= 3)
+         usage("m = amdemod(s,fc,fs)");
+  end
+  t = 0:1./fs:(length(s)-1)./fs;
+  e = s.*cos(2.*pi.*fc.*t);
+  [b a] = butter(5,fc.*2./fs);
+  m = filtfilt(b,a,e).*2;