added frequency burst detection, but not yet finished

2 files changed, 97 insertions, 63 deletions

diff --git a/src/lib/gsm_receiver_cf.cc b/src/lib/gsm_receiver_cf.cc
index e478c66..206bd5e 100644
--- a/src/lib/gsm_receiver_cf.cc
+++ b/src/lib/gsm_receiver_cf.cc
@@ -1,19 +1,19 @@
 /* -*- c++ -*- */
 /*
  * Copyright 2004 Free Software Foundation, Inc.
- * 
+ *
  * This file is part of GNU Radio
- * 
+ *
  * GNU Radio 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, or (at your option)
  * any later version.
- * 
+ *
  * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street,
@@ -26,94 +26,123 @@
 
 #include <gsm_receiver_cf.h>
 #include <gr_io_signature.h>
+#include <gr_math.h>
+#include <gsm_constants.h>
+#include <Assert.h>
 
-gsm_receiver_cf_sptr 
-gsm_make_receiver_cf ()
+
+gsm_receiver_cf_sptr
+gsm_make_receiver_cf(int osr)
 {
-  return gsm_receiver_cf_sptr (new gsm_receiver_cf ());
+  return gsm_receiver_cf_sptr(new gsm_receiver_cf(osr));
 }
 
-static const int MIN_IN = 1;	// mininum number of input streams
-static const int MAX_IN = 1;	// maximum number of input streams
-static const int MIN_OUT = 1;	// minimum number of output streams
-static const int MAX_OUT = 1;	// maximum number of output streams
+static const int MIN_IN = 1; // mininum number of input streams
+static const int MAX_IN = 1; // maximum number of input streams
+static const int MIN_OUT = 0; // minimum number of output streams
+static const int MAX_OUT = 1; // maximum number of output streams
 
 /*
  * The private constructor
  */
-gsm_receiver_cf::gsm_receiver_cf ()
-  : gr_block ("gsm_receiver",
-	      gr_make_io_signature (MIN_IN, MAX_IN, sizeof (gr_complex)),
-	      gr_make_io_signature (MIN_OUT, MAX_OUT, sizeof (float)))
+gsm_receiver_cf::gsm_receiver_cf(int osr)
+    : gr_block("gsm_receiver",
+               gr_make_io_signature(MIN_IN, MAX_IN, sizeof(gr_complex)),
+               gr_make_io_signature(MIN_OUT, MAX_OUT, 142 * sizeof(float))),
+    d_counter(0)
 {
 }
 
 /*
  * Virtual destructor.
  */
-gsm_receiver_cf::~gsm_receiver_cf ()
+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; //TODO include oversampling ratio here
 }
 
-int 
-gsm_receiver_cf::general_work (int noutput_items,
-			       gr_vector_int &ninput_items,
-			       gr_vector_const_void_star &input_items,
-			       gr_vector_void_star &output_items)
+int
+gsm_receiver_cf::general_work(int noutput_items,
+                              gr_vector_int &ninput_items,
+                              gr_vector_const_void_star &input_items,
+                              gr_vector_void_star &output_items)
 {
-  const float *in = (const float *) input_items[0];
+  const gr_complex *in = (const gr_complex *) input_items[0];
   float *out = (float *) output_items[0];
 
-  for (int i = 0; i < noutput_items; i++){
-    out[i] = in[i] * in[i];
-  }
+//  DCOUT(ninput_items[0]);
+//  DCOUT(noutput_items);
 
-  consume_each (noutput_items);
 
-  return noutput_items;
+  d_return = 0; //!
+  int start_pos = find_fcch_burst(in, ninput_items[0]);
+  for (int i = 0; i < TS_BITS; i++) {
+    out[i] = d_phase_diff_buffer[i+start_pos-USEFUL_BITS];
+  }
+  consume_each(start_pos);
+  d_counter += start_pos;
+  return d_return;
 }
 
-
-bool gsm_receiver_cf::get_fcch_burst()
+int gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
 {
+  for (int i = 0; (i < nitems - 1) && (i < BUFFER_SIZE); i++) {
+    gr_complex conjprod = in[i+1] * conj(in[i]);
+    float diff_angle = gr_fast_atan2f(imag(conjprod), real(conjprod));
+    d_phase_diff_buffer[i] = diff_angle;
+  }
+
   int hit_count = 0;
   int miss_count = 0;
   int start_pos = -1;
-/*
-  for ( int i=0; i < BBUF_SIZE; i++ ) {
-      if ( d_burst_buffer[i] > 0 ) {
-          if ( ! hit_count++ )
-            start_pos = i;
-        } else {
-          if ( hit_count >= FCCH_HITS_NEEDED ) {
-              break;
-            } else
-            if ( ++miss_count > FCCH_MAX_MISSES ) {
-                start_pos = -1;
-                hit_count = miss_count = 0;
-              }
-        }
+
+  d_return = 0;//!
+  
+  for (int i = 0; ; i++) {
+    if (i > nitems - USEFUL_BITS - 1) {
+      start_pos = nitems - USEFUL_BITS - 1;
+      break;
     }
 
-  //Do we have a match?
-  if ( start_pos >= 0 ) {
+    if (d_phase_diff_buffer[i] > 0) {
+      if (! hit_count) {
+        start_pos = i+USEFUL_BITS;
+      }
+      hit_count++;
+    } else if (hit_count >= FCCH_HITS_NEEDED) {
+      DCOUT("znalezione fcch na pozycji" << d_counter+start_pos-USEFUL_BITS);
+      d_return = 1;//!
+      break;
+    } else if (++miss_count > FCCH_MAX_MISSES) {
+      start_pos = -1;
+      hit_count = miss_count = 0;
+    }
+  }
+
+  /*
+    //Do we have a match?
+    if (start_pos >= 0) {
       //Is it within range? (we know it's long enough then too)
-      if ( start_pos < 2*MAX_CORR_DIST ) {
-          d_burst_start = start_pos;
-          d_bbuf_pos = 0; //load buffer from start
-          return FCCH;
-
-        } else {
-          //TODO: don't shift a tiny amount
-          shift_burst( start_pos - MAX_CORR_DIST );
-        }
+      if (start_pos < 2*MAX_CORR_DIST) {
+        d_burst_start = start_pos;
+        d_bbuf_pos = 0; //load buffer from start
+        return FCCH;
+      } else {
+        //TODO: don't shift a tiny amount
+        shift_burst(start_pos - MAX_CORR_DIST);
+      }
     } else {
       //Didn't find anything
       d_burst_start = MAX_CORR_DIST;
       d_bbuf_pos = 0; //load buffer from start
     }
+  */
+  //DCOUT("start_pos: " << start_pos);
 
-  return UNKNOWN;
-*/
+  return start_pos;
 }
 
diff --git a/src/lib/gsm_receiver_cf.h b/src/lib/gsm_receiver_cf.h
index 7067fb2..5bc7617 100644
--- a/src/lib/gsm_receiver_cf.h
+++ b/src/lib/gsm_receiver_cf.h
@@ -25,6 +25,8 @@
 #include <gr_block.h>
 #include <gr_complex.h>
 
+#define BUFFER_SIZE 4096
+
 class gsm_receiver_cf;
 
 /*
@@ -47,26 +49,29 @@ typedef boost::shared_ptr<gsm_receiver_cf> gsm_receiver_cf_sptr;
  * constructor is private.  howto_make_square_ff is the public
  * interface for creating new instances.
  */
-gsm_receiver_cf_sptr gsm_make_receiver_cf();
+gsm_receiver_cf_sptr gsm_make_receiver_cf( int osr );
 
 /*!
  * \brief Receives fcch
  * \ingroup block
- * \sa 
+ * \sa
  */
 
 class gsm_receiver_cf : public gr_block
 {
 
   private:
-    friend gsm_receiver_cf_sptr gsm_make_receiver_cf();
-
-    gsm_receiver_cf();
-    bool get_fcch_burst();
+    int d_counter;
+    int d_return;
+    float d_phase_diff_buffer[BUFFER_SIZE];
+    
+    friend gsm_receiver_cf_sptr gsm_make_receiver_cf( int osr );
+    gsm_receiver_cf( int osr );
+    int find_fcch_burst( const gr_complex *in, const int items );
 
   public:
     ~gsm_receiver_cf();
-
+    void forecast( int noutput_items, gr_vector_int &ninput_items_required );
     int general_work( int noutput_items,
                       gr_vector_int &ninput_items,
                       gr_vector_const_void_star &input_items,