octave spaß

phasenmodulation.m

@@ -0,0 +1,101 @@
+## Copyright (C) 2016 Valentin Gehrke
+## 
+## 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{retval} =} phasenmodulation (@var{input1}, @var{input2})
+##
+## @seealso{}
+## @end deftypefn
+
+## Author: Valentin Gehrke <s7745593@e03101>
+## Created: 2016-07-28
+
+datalen = 10;
+
+d = rand(1,datalen) > 0.5;
+
+#d = [ 1 0 1 0 1 1 1 0 1 0 0 0 1 0 0 1 0 1 0 1 1 0 1 1 0 0 0 1];
+n = 0:datalen-1;
+phases = [ -pi/2 pi/2 ];
+Tb = 0.5;
+fc = 5;
+fa = 200;
+
+subplot(6,1,1)
+stem(n,d)
+
+
+t = 0:(1/fa):(size(d,2)*Tb - 1/fa);
+phi = phases( d( floor(t/Tb) + 1) + 1);
+
+subplot(6,1,2)
+plot(t,phi)
+
+s = cos(2*pi*fc*t + phi);
+
+[bs,as] = butter(5,2*1.5*fc/fa);
+
+slow = filter(bs,as,s);
+
+subplot(6,1,3);
+vgl = cos(2*pi*fc*t);
+plot(t,slow,t,vgl);
+
+noise = 0.5 * randn(size(slow));
+
+sn = slow + noise;
+
+subplot(6,1,4);
+plot(t,sn);
+
+sr = sn .* cos(2*pi*fc*t);
+si = sn .* sin(2*pi*fc*t);
+
+[b,a] = butter(5,2*fc/fa);
+
+srlow = filter(b,a,sr);
+silow = filter(b,a,si);
+
+
+cmplxs = srlow + j*silow;
+
+phase = angle(cmplxs);
+
+
+m = zeros(size(phase));
+
+for i = 1:size(t,2)
+  [tmp, idx] = min(abs(phase(i) - phases));
+  m(i) = idx-1;
+endfor
+
+subplot(6,1,5);
+plot(t,phase,t,phases(m+1));
+
+ds = zeros(1,datalen);
+for i = 1:datalen;
+  ts = (i-1) * Tb;
+  te = i * Tb;
+  q = t > ts & t < te;
+  ds(i) = mean(m(q)) > 0.5;
+endfor
+
+subplot(6,1,6)
+err = (ds != d);
+cla
+stem(n(~err),ds(~err))
+hold on;
+stem(n(err),ds(err),'rx')
+hold off;