From d81b6383c00ded14dcafe09da31e9da695d2429d Mon Sep 17 00:00:00 2001
From: Valentin Gehrke <madmaurice@zom.bi>
Date: Thu, 28 Jul 2016 19:29:39 +0200
Subject: [PATCH] added bandpass filter

---
 phasenmodulation.m | 45 ++++++++++++++++++++++++++++-----------------
 1 file changed, 28 insertions(+), 17 deletions(-)

diff --git a/phasenmodulation.m b/phasenmodulation.m
index c821985..83e3463 100644
--- a/phasenmodulation.m
+++ b/phasenmodulation.m
@@ -24,24 +24,30 @@
 
 datalen = 10;
 
-d = rand(1,datalen) > 0.5;
+pilot = [ 1 0 1 0 ];
 
-#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;
+dr = rand(1,datalen) > 0.5;
+
+signallen = datalen + size(pilot,2);
+
+d = [ pilot dr ];
+n = 0:signallen-1;
 phases = [ -pi/2 pi/2 ];
-Tb = 0.5;
-fc = 5;
-fa = 200;
+Tb = 0.3;
+fc = 40;
+fa = 1000;
 
 subplot(6,1,1)
 stem(n,d)
 
+timelen = (signallen*Tb - 1/fa);
 
-t = 0:(1/fa):(size(d,2)*Tb - 1/fa);
+t = 0:(1/fa):timelen;
 phi = phases( d( floor(t/Tb) + 1) + 1);
 
 subplot(6,1,2)
 plot(t,phi)
+axis([0 timelen -pi pi])
 
 s = cos(2*pi*fc*t + phi);
 
@@ -50,30 +56,34 @@ s = cos(2*pi*fc*t + phi);
 slow = filter(bs,as,s);
 
 subplot(6,1,3);
-vgl = cos(2*pi*fc*t);
-plot(t,slow,t,vgl);
+plot(t,slow);
+axis([0 timelen -1.5 1.5])
 
-noise = 0.5 * randn(size(slow));
+noise = 1 * randn(size(slow));
 
 sn = slow + noise;
 
 subplot(6,1,4);
+
+[bbp,abp] = butter(5,[2*0.5*fc/fa , 2*1.5*fc/fa]);
+sbp = filter(bbp,abp,sn);
+
 plot(t,sn);
+axis([0 timelen -3 3])
 
-sr = sn .* cos(2*pi*fc*t);
-si = sn .* sin(2*pi*fc*t);
 
-[b,a] = butter(5,2*fc/fa);
+sr = sbp .* cos(2*pi*fc*t);
+si = sbp .* sin(2*pi*fc*t);
+
+[b,a] = butter(5,2*0.7*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)
@@ -83,9 +93,10 @@ endfor
 
 subplot(6,1,5);
 plot(t,phase,t,phases(m+1));
+axis([0 timelen -pi pi])
 
-ds = zeros(1,datalen);
-for i = 1:datalen;
+ds = zeros(1,signallen);
+for i = 1:signallen;
   ts = (i-1) * Tb;
   te = i * Tb;
   q = t > ts & t < te;