-fixed burst_cf sampling

4 files changed, 67 insertions, 61 deletions

diff --git a/gsm-tvoid/src/lib/gsm_burst.cc b/gsm-tvoid/src/lib/gsm_burst.cc
index cb896bc..00a5a95 100755
--- a/gsm-tvoid/src/lib/gsm_burst.cc
+++ b/gsm-tvoid/src/lib/gsm_burst.cc
@@ -358,14 +358,15 @@ void gsm_burst::shift_burst(int shift_bits)
 //of the mean phase  from pi/2.
 void gsm_burst::calc_freq_offset(void) 
 {
-	int start = d_burst_start + 10;
-	int end = d_burst_start + USEFUL_BITS - 10;
+	const int padding = 20;
+	int start = d_burst_start + padding;
+	int end = d_burst_start + USEFUL_BITS - padding;
 	
 	float sum = 0.0;
 	for (int j = start; j <= end; j++) {
 		sum += d_burst_buffer[j];
 	}
-	float mean = sum / ((float)USEFUL_BITS - 20.0);
+	float mean = sum / ((float)USEFUL_BITS - 2.0 * (float)padding);
 	
 	float p_off = mean - (M_PI / 2);
 	d_freq_offset = p_off * 1625000.0 / (12.0 * M_PI);
@@ -701,6 +702,7 @@ int gsm_burst::get_burst(void)
 
 		/////////////////////
 		//start tune testing
+#ifdef TEST_TUNE_TIMING
 		static int good_count = -1; //-1: wait sch, >=0: got sch, counting
 	
 		if (UNKNOWN == d_burst_type) {
@@ -732,6 +734,7 @@ int gsm_burst::get_burst(void)
 				}
 			}
 		}
+#endif
 		//end tune testing	
 		/////////////////////
 
diff --git a/gsm-tvoid/src/lib/gsm_burst_cf.cc b/gsm-tvoid/src/lib/gsm_burst_cf.cc
index 08ff7ba..821b41f 100755
--- a/gsm-tvoid/src/lib/gsm_burst_cf.cc
+++ b/gsm-tvoid/src/lib/gsm_burst_cf.cc
@@ -25,6 +25,7 @@ gsm_burst_cf::gsm_burst_cf (gr_feval_ll *t, float sample_rate) :
 				gr_make_io_signature (MIN_IN, MAX_IN, sizeof (gr_complex)),
 				gr_make_io_signature (MIN_OUT, MAX_OUT, USEFUL_BITS * sizeof (float))),
 	d_clock_counter(0.0),
+	d_mu(0.5),
 	d_last_sample(0.0,0.0),
 	d_interp(new gri_mmse_fir_interpolator_cc())
 
@@ -37,7 +38,7 @@ gsm_burst_cf::gsm_burst_cf (gr_feval_ll *t, float sample_rate) :
 	fprintf(stderr,"Sample interval      : %e\n",d_sample_interval);
 	fprintf(stderr,"Relative sample rate : %g\n",d_relative_sample_rate);
 		
-	set_history(4); 
+	set_history(4); //need history for interpolator
 	
 }
 
@@ -68,70 +69,70 @@ int gsm_burst_cf::general_work (int noutput_items,
 	int ninput = ninput_items[0];
 	//fprintf(stderr,"#i=%d/#o=%d",n_input,noutput_items);
 
-	int  ni = ninput - d_interp->ntaps();  // interpolator need -4/+3 samples NTAPS = 8
+	int  ni = ninput - d_interp->ntaps() - 16;  // interpolator need -4/+3 samples NTAPS = 8  , - 16 for safety margin
 	
 	while (( rval < noutput_items) && ( ii < ni ) ) {
 		//clock symbols 
 		//TODO: this is very basic and can be improved.  Need tracking...
 		//TODO: use burst_start offsets as timing feedback
 		//TODO: save complex samples for Viterbi EQ
-		if ( d_clock_counter >= GSM_SYMBOL_PERIOD) {
-
-			d_clock_counter -= GSM_SYMBOL_PERIOD; //reset clock for next sample, keep the remainder
-
-			//float mu = 1.0 - d_clock_counter / GSM_SYMBOL_PERIOD;
-			float mu = d_clock_counter / GSM_SYMBOL_PERIOD;
-			gr_complex sample = d_interp->interpolate (&in[ii], mu);	//FIXME: this seems noisy, make sure it is being used correctly
+		
+		//from m&m
+		gr_complex sample = d_interp->interpolate (&in[ii], d_mu);	//FIXME: this seems noisy, make sure it is being used correctly
+		
+		gr_complex conjprod = sample * conj(d_last_sample);
+		float diff_angle = gr_fast_atan2f(imag(conjprod), real(conjprod));
 
-			gr_complex conjprod = sample * conj(d_last_sample);
-			float diff_angle = gr_fast_atan2f(imag(conjprod), real(conjprod));
+		d_last_sample = sample;
 
-			d_last_sample = sample;
-	
-			assert(d_bbuf_pos <= BBUF_SIZE );
-			
-			if (d_bbuf_pos >= 0)	//could be negative offset from burst alignment.  TODO: perhaps better just to add some padding to the buffer
-				d_burst_buffer[d_bbuf_pos] = diff_angle;
-			
-			d_bbuf_pos++;
-			
-			if ( d_bbuf_pos >= BBUF_SIZE ) { 
-			
-				if (get_burst()) {
-					//found a burst, send to output
-					//ensure that output data is in range
-					int b = d_burst_start;
-					if (b < 0)
-						b = 0;
-					else if (b >= 2 * MAX_CORR_DIST)
-						b = 2 * MAX_CORR_DIST - 1;
+		assert(d_bbuf_pos <= BBUF_SIZE );
+		
+		if (d_bbuf_pos >= 0)	//could be negative offset from burst alignment.  TODO: perhaps better just to add some padding to the buffer
+			d_burst_buffer[d_bbuf_pos] = diff_angle;
 		
-					memcpy(out+rval*USEFUL_BITS, d_burst_buffer + b, USEFUL_BITS*sizeof(float));
-					rval++;
-
-					switch ( d_clock_options & QB_MASK ) {
-					case QB_QUARTER: //extra 1/4 bit each burst
-						d_clock_counter -= GSM_SYMBOL_PERIOD / 4.0; 
-						break;
-					case QB_FULL04:	//extra bit on timeslot 0 & 4
-						if (!(d_ts%4))
-							d_clock_counter -= GSM_SYMBOL_PERIOD; 
-						break;
-					case QB_NONE:	//don't adjust for quarter bits at all
-					default:
-						break;
-					}
-					
-					d_last_burst_s_count = d_sample_count;	
-					
-					//fprintf(stderr,"clock: %f, pos: %d\n",d_clock_counter,d_bbuf_pos);
+		d_bbuf_pos++;
+		
+		if ( d_bbuf_pos >= BBUF_SIZE ) { 
+		
+			if (get_burst()) {
+				//found a burst, send to output
+				//ensure that output data is in range
+				int b = d_burst_start;
+				if (b < 0)
+					b = 0;
+				else if (b >= 2 * MAX_CORR_DIST)
+					b = 2 * MAX_CORR_DIST - 1;
+	
+				memcpy(out+rval*USEFUL_BITS, d_burst_buffer + b, USEFUL_BITS*sizeof(float));
+				rval++;
+
+				switch ( d_clock_options & QB_MASK ) {
+				case QB_QUARTER: //extra 1/4 bit each burst
+					d_mu -= d_relative_sample_rate / 4.0;
+					//d_clock_counter -= GSM_SYMBOL_PERIOD / 4.0; 
+					break;
+				case QB_FULL04:	//extra bit on timeslot 0 & 4
+					if (!(d_ts%4))
+						d_mu -= d_relative_sample_rate;
+						//d_clock_counter -= GSM_SYMBOL_PERIOD; 
+					break;
+				case QB_NONE:	//don't adjust for quarter bits at all
+				default:
+					break;
 				}
-			}	   
-		}
-
-		d_clock_counter += d_sample_interval;
-		d_sample_count++;
- 		ii++;
+				
+				d_last_burst_s_count = d_sample_count;
+				
+				//fprintf(stderr,"clock: %f, pos: %d\n",d_clock_counter,d_bbuf_pos);
+			}
+		}	   
+		
+		//TODO: timing adjust
+		//d_mu = d_mu + d_omega + d_gain_mu * mm_val;
+		d_mu += d_relative_sample_rate;
+		ii += (int)floor(d_mu);
+		d_sample_count += (int)floor(d_mu);
+		d_mu -= floor(d_mu);
 	}
 	
 	//fprintf(stderr,"/ii=%d/rval=%d\n",ii,rval);
diff --git a/gsm-tvoid/src/lib/gsm_burst_cf.h b/gsm-tvoid/src/lib/gsm_burst_cf.h
index 2b806e0..40ccc83 100755
--- a/gsm-tvoid/src/lib/gsm_burst_cf.h
+++ b/gsm-tvoid/src/lib/gsm_burst_cf.h
@@ -20,11 +20,13 @@ private:
 	gsm_burst_cf(gr_feval_ll *,float);  
 	
 	//clocking parameters
-	float			d_relative_sample_rate;
 	double			d_sample_interval;
 	double			d_clock_counter;
 	gr_complex		d_last_sample;
 
+	float			d_relative_sample_rate;		//omega
+	float			d_mu;
+	
 	gri_mmse_fir_interpolator_cc 	*d_interp;  //sub-sample interpolator from GR
 		
 public:
diff --git a/gsm-tvoid/src/python/gsm_scan.py b/gsm-tvoid/src/python/gsm_scan.py
index 51ff92e..577acf4 100755
--- a/gsm-tvoid/src/python/gsm_scan.py
+++ b/gsm-tvoid/src/python/gsm_scan.py
@@ -36,10 +36,10 @@ class burst_callback(gr.feval_ll):
 		try:
 			#print "burst_callback: ", x, "\n";
 			if gsm.BURST_CB_ADJ_OFFSET == x:
-				return 0
+				#return 0
 				#TODO: rework so this will work on file input
 				last_offset = self.fg.burst.last_freq_offset()
-				if 20000.0 > abs(last_offset) > 200.0:
+				if 20000.0 > abs(last_offset) > 500.0:
 					self.fg.offset -= last_offset
 					print "burst_callback: ADJ_OFFSET:", last_offset, " ARFCN: ", self.fg.arfcn, "\n";
 					self.fg.set_channel(self.fg.arfcn)