From 132074e45c10089a32ccb4113d2c5f2f08796a01 Mon Sep 17 00:00:00 2001
From: drowe67 <drowe67@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Tue, 26 Feb 2013 02:35:01 +0000
Subject: [PATCH] a little more work on the sync algorithm

git-svn-id: https://svn.code.sf.net/p/freetel/code@1171 01035d8c-6547-0410-b346-abe4f91aad63
---
 codec2-dev/octave/fdmdv.m       | 28 +++++++++++++++++++++-------
 codec2-dev/octave/fdmdv_demod.m |  3 ++-
 codec2-dev/octave/fdmdv_ut.m    |  7 ++++---
 3 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/codec2-dev/octave/fdmdv.m b/codec2-dev/octave/fdmdv.m
index 701fdcc0..7102d6fc 100644
--- a/codec2-dev/octave/fdmdv.m
+++ b/codec2-dev/octave/fdmdv.m
@@ -758,7 +758,7 @@ endfunction
 % then switch to a more robust tracking algorithm.  If we lose sync we switch
 % back to acquire mode for fast-requisition.
 
-function [track state] = freq_state(sync_bit, state)
+function [track state bad_sync] = freq_state(sync_bit, state, bad_sync)
 
   % acquire state, look for 6 symbol 010101 sequence from sync bit
 
@@ -799,6 +799,7 @@ function [track state] = freq_state(sync_bit, state)
   if state == 5
     if sync_bit == 1
       next_state = 6;
+      bad_sync = 0;
     else 
       next_state = 0;
     end        
@@ -807,20 +808,33 @@ function [track state] = freq_state(sync_bit, state)
   % states 6 and above are track mode, make sure we keep getting 0101 sync bit sequence
 
   if state == 6
+    next_state = 7;
     if sync_bit == 0
-      next_state = 7;
-    else 
-      next_state = 0;
+      bad_sync = 0;
+    else
+      printf("inc ");
+      bad_sync++;
+      if bad_sync > 2
+        next_state = 0;
+      end
     end        
   end
+
   if state == 7
+    next_state = 6;
     if sync_bit == 1
-      next_state = 6;
-    else 
-      next_state = 0;
+      bad_sync = 0;
+    else
+      printf("inc ");
+      bad_sync++;
+      if bad_sync > 2
+        next_state = 0;
+      end
     end        
   end
 
+  %printf("state: %d  next_state: %d  sync_bit: %d bad_sync: %d\n", state, next_state, sync_bit, bad_sync);
+
   state = next_state;
   if state >= 6
     track = 1;
diff --git a/codec2-dev/octave/fdmdv_demod.m b/codec2-dev/octave/fdmdv_demod.m
index b08d7ffa..94c16900 100644
--- a/codec2-dev/octave/fdmdv_demod.m
+++ b/codec2-dev/octave/fdmdv_demod.m
@@ -51,6 +51,7 @@ function fdmdv_demod(rawfilename, nbits, errorpatternfilename)
   track_log = [];
   track = 0;
   fest_state = 0;
+  bad_sync = 0;
 
   % spectrum states
 
@@ -125,7 +126,7 @@ function fdmdv_demod(rawfilename, nbits, errorpatternfilename)
 
     % freq est state machine
 
-    [track fest_state] = freq_state(sync, fest_state);
+    [track fest_state bad_sync] = freq_state(sync, fest_state, bad_sync);
     track_log = [track_log track];
 
     % count bit errors if we find a test frame
diff --git a/codec2-dev/octave/fdmdv_ut.m b/codec2-dev/octave/fdmdv_ut.m
index c89aa78c..871cfcc8 100644
--- a/codec2-dev/octave/fdmdv_ut.m
+++ b/codec2-dev/octave/fdmdv_ut.m
@@ -12,8 +12,8 @@ fdmdv;               % load modem code
  
 % Simulation Parameters --------------------------------------
 
-frames = 50*10;
-EbNo_dB = 10.3;
+frames = 100;
+EbNo_dB = 7.3;
 Foff_hz = 0;
 modulation = 'dqpsk';
 hpa_clip = 150;
@@ -93,6 +93,7 @@ foff_phase = 1;
 t = 0;
 foff = 0;
 fest_state = 0;
+bad_sync = 0;
 track = 0;
 track_log = [];
 
@@ -212,7 +213,7 @@ for f=1:frames
   
   % freq est state machine
 
-  [track fest_state] = freq_state(sync, fest_state);
+  [track fest_state bad_sync] = freq_state(sync, fest_state, bad_sync);
   track_log = [track_log track];
 
   % Update SNR est
-- 
2.25.1