just next cleanup, move along

3 files changed, 79 insertions, 30 deletions

diff --git a/src/lib/gsm_constants.h b/src/lib/gsm_constants.h
index ded8cb4..520ff4f 100644
--- a/src/lib/gsm_constants.h
+++ b/src/lib/gsm_constants.h
@@ -22,10 +22,12 @@
 #define FRAME_BITS        (TS_PER_FRAME * TS_BITS + 2) // 156.25 * 8
 #define FCCH_POS          TAIL_BITS
 #define SYNC_POS          39
-#define TRAIN_POS         58
-#define SAFETY_MARGIN     6
+#define TRAIN_POS         TAIL_BITS + DATA_BITS + 5 //first 5 bits of a training sequence
+//aren't used for channel impulse response estimation
+#define TRAIN_BEGINNING   5
+#define SAFETY_MARGIN     6   //
 
-#define FCCH_HITS_NEEDED        (USEFUL_BITS - 4) 
+#define FCCH_HITS_NEEDED        (USEFUL_BITS - 4)
 #define FCCH_MAX_MISSES         1
 #define FCCH_MAX_FREQ_OFFSET    100
 
@@ -38,9 +40,9 @@ static const unsigned char SYNC_BITS[] = {
   0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1
 };
 
-const unsigned FCCH_FRAMES[] = {0,10,20,30,40};
-const unsigned SCH_FRAMES[] = {1,11,21,31,41};
-const unsigned BCCH_FRAMES[] = {2,3,4,5,  12}; //remove 12
+const unsigned FCCH_FRAMES[] = {0, 10, 20, 30, 40};
+const unsigned SCH_FRAMES[] = {1, 11, 21, 31, 41};
+const unsigned BCCH_FRAMES[] = {2, 3, 4, 5};
 
 // Sync             : .+...++.+..+++.++++++.++++++....++.+..+.+.+++.+.+...+..++++..+..
 // Diff Encoded Sync: .++..+.+++.+..++.....++.....+...+.+++.+++++..+++++..++.+...+.++.
@@ -91,6 +93,40 @@ static const unsigned char dummy_burst[] = {
   1, 1, 1, 0, 1, 0, 1, 0
 };
 
+
+/*
+ * The frequency correction burst is used for frequency synchronization
+ * of the mobile.  This is broadcast in TS0 together with the SCH and
+ * BCCH.
+ *
+ * Modulating the bits below causes a spike at 62.5kHz above (below for
+ * COMPACT) the center frequency.  One can use this spike with a narrow
+ * band filter to accurately determine the center of the channel.
+ */
+static const unsigned char fc_fb[] = {               //I don't use this tables, 
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    //I copied this here from burst_types.h because 
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    //the description is very informative - p.krysik
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+static const unsigned char fc_compact_fb[] = {
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0,
+  1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0
+};
+
 //Diff encoded train_seq
 //TSC0: +.++.+++..+...++..++.+++..
 //TSC1: +.+++.++..++...+..++.+++..
diff --git a/src/lib/gsm_receiver_cf.cc b/src/lib/gsm_receiver_cf.cc
index c47e111..c1280f4 100644
--- a/src/lib/gsm_receiver_cf.cc
+++ b/src/lib/gsm_receiver_cf.cc
@@ -75,10 +75,10 @@ gsm_receiver_cf::gsm_receiver_cf(gr_feval_dd *tuner, int osr)
     d_burst_nr(osr)
 {
   int i;
-  gmsk_mapper(SYNC_BITS, N_SYNC_BITS, d_sch_training_seq, gr_complex(0.0,-1.0));
+  gmsk_mapper(SYNC_BITS, N_SYNC_BITS, d_sch_training_seq, gr_complex(0.0, -1.0));
 
   for (i = 0; i < TRAIN_SEQ_NUM; i++) {
-    gmsk_mapper(train_seq[i], N_TRAIN_BITS, d_norm_training_seq[i], gr_complex(1.0,0.0));
+    gmsk_mapper(train_seq[i], N_TRAIN_BITS, d_norm_training_seq[i], gr_complex(1.0, 0.0));
   }
 }
 
@@ -91,7 +91,7 @@ gsm_receiver_cf::~gsm_receiver_cf()
 
 void gsm_receiver_cf::forecast(int noutput_items, gr_vector_int &ninput_items_required)
 {
-  ninput_items_required[0] = noutput_items * (TS_BITS + 2 * SAFETY_MARGIN) * d_OSR;
+  ninput_items_required[0] = noutput_items * floor((TS_BITS + 2 * GUARD_PERIOD) * d_OSR);
 }
 
 int
@@ -207,13 +207,11 @@ gsm_receiver_cf::general_work(int noutput_items,
         case normal_burst:
           burst_start = get_norm_chan_imp_resp(in, chan_imp_resp, TRAIN_SEARCH_RANGE);
           detect_burst(in, &d_channel_imp_resp[0], burst_start, output_binary);
-//           printf("burst = [ ");
-// 
-//           for (int i = 0; i < BURST_SIZE ; i++) {
-//             printf(" %d", output_binary[i]);
-//           }
-//           printf("];\n");
-
+          printf("burst = [ ");
+          for (int i = 0; i < BURST_SIZE ; i++) {
+            printf(" %d", output_binary[i]);
+          }
+          printf("];\n");
           break;
 
         case rach_burst:
@@ -596,12 +594,13 @@ int gsm_receiver_cf::get_norm_chan_imp_resp(const gr_complex *in, gr_complex * c
   int chan_imp_resp_center;
   float max_correlation = 0;
   float energy = 0;
-  
-  int search_start_pos = floor((TRAIN_POS + GUARD_PERIOD) * d_OSR);
-  int search_stop_pos = search_start_pos + search_range * d_OSR;
+
+  int search_center = (int)((TRAIN_POS + GUARD_PERIOD) * d_OSR);
+  int search_start_pos = search_center+1;
+  int search_stop_pos = search_center + d_chan_imp_length * d_OSR + 2*d_OSR;
 
   for (int ii = search_start_pos; ii < search_stop_pos; ii++) {
-    gr_complex correlation = correlate_sequence(&d_norm_training_seq[d_bcc][5], &in[ii], N_TRAIN_BITS - 10);
+    gr_complex correlation = correlate_sequence(&d_norm_training_seq[d_bcc][TRAIN_BEGINNING], &in[ii], N_TRAIN_BITS - 10);
 
     correlation_buffer.push_back(correlation);
     power_buffer.push_back(pow(abs(correlation), 2));
@@ -615,24 +614,27 @@ int gsm_receiver_cf::get_norm_chan_imp_resp(const gr_complex *in, gr_complex * c
     energy = 0;
 
     for (int ii = 0; ii < (d_chan_imp_length)*d_OSR; ii++, iter_ii++) {
+//     for (int ii = 0; ii < (d_chan_imp_length); ii++) {
       if (iter_ii == power_buffer.end()) {
         loop_end = true;
         break;
       }
       energy += (*iter_ii);
+//       iter_ii = iter_ii + d_OSR;
     }
     if (loop_end) {
       break;
     }
     iter++;
+//      std::cout << energy << "\n";
+
     window_energy_buffer.push_back(energy);
   }
-  
-
+//   std::cout << window_energy_buffer.size() << "\n";
 
   strongest_window_nr = max_element(window_energy_buffer.begin(), window_energy_buffer.end()) - window_energy_buffer.begin();
   d_channel_imp_resp.clear();
-  strongest_window_nr = 36;
+//   strongest_window_nr = 3;
 
   max_correlation = 0;
   for (int ii = 0; ii < (d_chan_imp_length)*d_OSR; ii++) {
@@ -644,9 +646,20 @@ int gsm_receiver_cf::get_norm_chan_imp_resp(const gr_complex *in, gr_complex * c
     d_channel_imp_resp.push_back(correlation);
     chan_imp_resp[ii] = correlation;
   }
+//WE WANT TO USE THE FIRST SAMPLE OF THE IMPULSERESPONSE, AND THE
+// CORRESPONDING SAMPLES OF THE RECEIVED SIGNAL.                                 
+// THE VARIABLE sync_w SHOULD CONTAIN THE BEGINNING OF THE USED PART OF          
+// TRAINING SEQUENCE, WHICH IS 3+57+1+6=67 BITS INTO THE BURST. THAT IS          
+// WE HAVE THAT sync_T16 EQUALS FIRST SAMPLE IN BIT NUMBER 67.
+
+
+  burst_start = search_start_pos + chan_imp_resp_center + strongest_window_nr - 66 * d_OSR - 2 * d_OSR + 2; 
+// COMPENSATING FOR THE 2 Tb DELAY INTRODUCED IN THE GMSK MODULATOR.             
+// EACH BIT IS STRECHED OVER A PERIOD OF 3 Tb WITH ITS MAXIMUM VALUE             
+// IN THE LAST BIT PERIOD. HENCE, burst_start IS 2 * OSR
+//compute burst start 
+  std::cout << " burst_start: " << (float)burst_start/(float)d_OSR<< " center: " << ((float)(search_start_pos + strongest_window_nr + chan_imp_resp_center))/d_OSR << " stronegest window nr: " <<  strongest_window_nr << "\n";
 
-  std::cout << "center: " << strongest_window_nr + chan_imp_resp_center  << " stronegest window nr: " <<  strongest_window_nr << "\n";
-  
-  burst_start = search_start_pos + strongest_window_nr + chan_imp_resp_center - 66 * d_OSR - 2 * d_OSR + 2;
   return burst_start;
+
 }
diff --git a/src/lib/gsm_receiver_cf.h b/src/lib/gsm_receiver_cf.h
index 978576b..e07eb60 100644
--- a/src/lib/gsm_receiver_cf.h
+++ b/src/lib/gsm_receiver_cf.h
@@ -164,6 +164,10 @@ class burst_counter
     unsigned get_offset(){
        return (unsigned)d_offset;
     }
+    //!!
+    float get_first_sample_offset(){
+      return d_first_sample_offset;
+    }
 };
 
 class channel_configuration
@@ -255,10 +259,6 @@ class gsm_receiver_cf : public gr_block
     //variables used to store result of the find_fcch_burst fuction
     int d_fcch_start_pos;
     float d_freq_offset;
-//     double d_best_sum;
-
-//    int d_fcch_count; //!!!
-//    double d_x_temp, d_x2_temp, d_mean;//!!
 
     burst_counter d_burst_nr;
     channel_configuration d_channel_conf;