From: baobrien <baobrien@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Sun, 13 Sep 2015 02:33:05 +0000 (+0000)
Subject: A little further on the FSK4 thing. Now it probably decodes to real symbols
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=f4fa21cdd4d8fce8419745f616154894429a4838;p=freetel-svn-tracking.git

A little further on the FSK4 thing. Now it probably decodes to real symbols

git-svn-id: https://svn.code.sf.net/p/freetel/code@2321 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/octave/fsk4.m b/codec2-dev/octave/fsk4.m
index f5590fa2..a79cd852 100644
--- a/codec2-dev/octave/fsk4.m
+++ b/codec2-dev/octave/fsk4.m
@@ -57,7 +57,6 @@ function [tx, tx_filt] = fsk4_mod(fsk4_states, tx_bits)
     lbits = [lbits 0]
   end
   tx_symbols = lbits + hbits*2 + 1;
-  hist(tx_symbols);
   M = fsk4_states.M;
   nsym = length(tx_symbols);
   nsam = nsym*M;
@@ -100,10 +99,29 @@ endfunction
 function sym = fsk4_demod_fmrid(fsk4_states, rx)
   afmd = analog_fm_demod(fsk4_states.fm_states,rx);
   sym = afsym = idmp(afmd,10);
-  for i=(1:length(afsym))
-    
+  
+  %Even and odd symbol error.
+  erreven = 0;
+  errodd  = 0;
+  % Demod symbol map. I should probably figure a better way to do this.
+  % After integrating, the high symbol tends to be about 7.5
+  dmsyms = rot90(fsk4_states.symmap * 7.5);
+
+  oddsyms  = afsym(1:2:length(afsym));
+  evensyms = afsym(2:2:length(afsym));
+  [errseven,deceven] = min(abs(evensyms - dmsyms));
+  [errsodd ,decodd ] = min(abs(oddsyms  - dmsyms));
+
+  erreven = mean(errseven)
+  errodd  = mean(errsodd )
+
+  if erreven < errodd
+    sym = deceven;
+  else
+    sym = decodd;
   end
-  eyediagram(afsym,4);
+  eyediagram(decodd ,4);
+  eyediagram(deceven,4);
   %todo: write the thing that finds the symbols in the even/odd integrator output.
 endfunction