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-rw-r--r--src/lib/Assert.h2
-rw-r--r--src/lib/gsm_constants.h2
-rw-r--r--src/lib/gsm_receiver_cf.cc219
-rw-r--r--src/lib/gsm_receiver_cf.h38
4 files changed, 195 insertions, 66 deletions
diff --git a/src/lib/Assert.h b/src/lib/Assert.h
index 6c04f18..acfb3f7 100644
--- a/src/lib/Assert.h
+++ b/src/lib/Assert.h
@@ -26,6 +26,8 @@
#include "stdio.h"
#include <iostream>
+#define NDEBUG
+
/**@name Macros for standard messages. */
//@{
#define COUT(text) { std::cout << text << std::endl; }
diff --git a/src/lib/gsm_constants.h b/src/lib/gsm_constants.h
index 01dfb22..62dc86b 100644
--- a/src/lib/gsm_constants.h
+++ b/src/lib/gsm_constants.h
@@ -21,7 +21,7 @@
#define TRAIN_POS 58
#define FCCH_HITS_NEEDED (USEFUL_BITS - 4)
-#define FCCH_MAX_MISSES 2
+#define FCCH_MAX_MISSES 1
static const int SYNC_BITS[] = {
1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0,
diff --git a/src/lib/gsm_receiver_cf.cc b/src/lib/gsm_receiver_cf.cc
index 4f43f2b..3b0e426 100644
--- a/src/lib/gsm_receiver_cf.cc
+++ b/src/lib/gsm_receiver_cf.cc
@@ -28,7 +28,6 @@
#include <gr_io_signature.h>
#include <gr_math.h>
#include <math.h>
-#include <gsm_constants.h>
#include <Assert.h>
#include <algorithm>
@@ -53,16 +52,18 @@ gsm_receiver_cf::gsm_receiver_cf(gr_feval_dd *tuner, 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_osr(osr),
+ d_OSR(osr),
d_tuner(tuner),
d_prev_freq_offset(0),
- d_phase_diff_buffer(BUFFER_SIZE),
+ d_phase_diff_buffer(BUFFER_SIZE * osr),
d_counter(0),
d_x_temp(0),
d_x2_temp(0),
d_fcch_count(0),
+ d_fcch_start_pos(0),
d_state(fcch_search)
{
+ gmsk_mapper(SYNC_BITS, d_sch_training_seq, N_SYNC_BITS);
}
/*
@@ -85,7 +86,7 @@ gsm_receiver_cf::general_work(int noutput_items,
{
const gr_complex *in = (const gr_complex *) input_items[0];
float *out = (float *) output_items[0];
- int produced_out;
+ int produced_out = 0;
switch (d_state) {
@@ -93,7 +94,7 @@ gsm_receiver_cf::general_work(int noutput_items,
if (find_fcch_burst(in, ninput_items[0])) {
produced_out = 1;
- d_state = fcch_search;
+ d_state = sch_search;
} else {
produced_out = 0;
d_state = fcch_search;
@@ -102,6 +103,46 @@ gsm_receiver_cf::general_work(int noutput_items,
break;
case sch_search:
+
+ if (find_sch_burst(in, ninput_items[0], out)) {
+
+ d_state = sch_search;
+ } else {
+ for (int i = 0; i < ninput_items[0] - N_SYNC_BITS; i++) {
+ gr_complex result;
+ d_counter++;
+ int ninput = N_SYNC_BITS - 10;
+ const gr_complex * input_signal = in + i;
+ gr_complex * sequence = &d_sch_training_seq[5];
+ result = correlation(&d_sch_training_seq[5], in + i, N_SYNC_BITS-10);
+ if (abs(result) > 60000) {
+ std::cout << "Max val: " << abs(result) << " position: " << d_counter - d_fcch_start_pos << std::endl;
+//
+// for (int j = 1; j <= 54; j++) {
+// std::cout << sequence[j-1] << " * " << conj(input_signal[(j * d_OSR)]) << std::endl;
+// }
+//
+// gr_complex result2(0, 0);
+//
+// for (int j = 1; j <= 54; j++) {
+// result2 += sequence[j-1] * conj(input_signal[(j * d_OSR)]);
+// }
+//
+// std::cout << "Spr: " << abs(result2) << std::endl;
+//
+// std::cout << std::endl;
+ }
+
+
+// std::cout << "(" << real(in[i]) << "," << imag(in[i]) << ")\n";
+// std::cout << "(" << real(result) << "," << imag(result) << ")\n";
+ }
+
+ consume_each(ninput_items[0]);
+
+ d_state = sch_search;
+ }
+
break;
}
@@ -116,14 +157,15 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
{
float phase_diff = 0;
gr_complex conjprod;
- int hit_count, miss_count, start_pos;
+ int hit_count = 0;
+ int miss_count = 0;
+ int start_pos;
float min_phase_diff, max_phase_diff, lowest_max_min_diff;
- float sum, best_sum;
int to_consume = 0;
- int i = 0;
+ int sample_number = 0;
bool end = false;
- bool result;
+ bool result = false;
circular_buffer_float::iterator buffer_iter;
@@ -133,7 +175,7 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
fcch_search_state = init;
- while ((!end) && (i < nitems)) {
+ while (!end) {
switch (fcch_search_state) {
case init:
@@ -147,23 +189,22 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
break;
case search:
- i++;
+ sample_number++;
- if (i > nitems - BUFFER_SIZE) {
- to_consume = i;
+ if (sample_number > nitems - BUFFER_SIZE * d_OSR) {
+ to_consume = sample_number;
fcch_search_state = search_fail;
- }
-
- conjprod = in[i] * conj(in[i-1]);
+ } else {
- phase_diff = gr_fast_atan2f(imag(conjprod), real(conjprod));
+ conjprod = in[sample_number] * conj(in[sample_number-1]);
+ phase_diff = gr_fast_atan2f(imag(conjprod), real(conjprod));
- if (phase_diff > 0) {
-// start_pos = i - 1;
- to_consume = i;
- fcch_search_state = found_something;
- } else {
- fcch_search_state = search;
+ if (phase_diff > 0) {
+ to_consume = sample_number;
+ fcch_search_state = found_something;
+ } else {
+ fcch_search_state = search;
+ }
}
break;
@@ -176,42 +217,42 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
miss_count++;
}
- //DCOUT("d_phase_diff_buffer.size(): " << d_phase_diff_buffer.size() << " hit_count: " << hit_count);
-
- if ((miss_count >= FCCH_MAX_MISSES) && (hit_count <= FCCH_HITS_NEEDED)) {
+ if ((miss_count >= FCCH_MAX_MISSES * d_OSR) && (hit_count <= FCCH_HITS_NEEDED * d_OSR)) {
fcch_search_state = init;
+ // DCOUT("hit_count: " << hit_count << " miss_count: " << miss_count << " d_counter: " << d_counter);
continue;
- } else if ((miss_count >= FCCH_MAX_MISSES) && (hit_count > FCCH_HITS_NEEDED)) {
+ } else if ((miss_count >= FCCH_MAX_MISSES * d_OSR) && (hit_count > FCCH_HITS_NEEDED * d_OSR)) {
fcch_search_state = fcch_found;
continue;
- } else if ((miss_count < FCCH_MAX_MISSES) && (hit_count > FCCH_HITS_NEEDED)) {
+ } else if ((miss_count < FCCH_MAX_MISSES * d_OSR) && (hit_count > FCCH_HITS_NEEDED * d_OSR)) {
//find difference between minimal and maximal element in the buffer
//for FCCH this value should be low
//this part is searching for a region where this value is lowest
min_phase_diff = *(min_element(d_phase_diff_buffer.begin(), d_phase_diff_buffer.end()));
max_phase_diff = *(max_element(d_phase_diff_buffer.begin(), d_phase_diff_buffer.end()));
-
- if(lowest_max_min_diff > max_phase_diff - min_phase_diff){
+
+ if (lowest_max_min_diff > max_phase_diff - min_phase_diff) {
lowest_max_min_diff = max_phase_diff - min_phase_diff;
- start_pos = i - FCCH_HITS_NEEDED;
+ start_pos = sample_number - FCCH_HITS_NEEDED * d_OSR - FCCH_MAX_MISSES * d_OSR;
d_best_sum = 0;
+
for (buffer_iter = (d_phase_diff_buffer.begin());
buffer_iter != (d_phase_diff_buffer.end());
buffer_iter++) {
- d_best_sum += *buffer_iter;
+ d_best_sum += *buffer_iter - (M_PI / 2) / d_OSR;
}
- DCOUT(d_best_sum);
}
}
- i++;
+ sample_number++;
- if (i >= nitems) {
+ if (sample_number >= nitems) {
fcch_search_state = search_fail;
continue;
}
- conjprod = in[i] * conj(in[i-1]);
+ conjprod = in[sample_number] * conj(in[sample_number-1]);
+
phase_diff = gr_fast_atan2f(imag(conjprod), real(conjprod));
d_phase_diff_buffer.push_back(phase_diff);
@@ -221,10 +262,11 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
case fcch_found:
DCOUT("znalezione fcch na pozycji" << d_counter + start_pos);
- to_consume = start_pos + FCCH_HITS_NEEDED + 1;
+ to_consume = start_pos + FCCH_HITS_NEEDED * d_OSR + 1;
/* mean = d_best_sum / FCCH_HITS_NEEDED;
phase_offset = mean - (M_PI / 2);
freq_offset = phase_offset * 1625000.0 / (12.0 * M_PI);*/
+ d_fcch_start_pos = d_counter + start_pos;
compute_freq_offset();
end = true;
result = true;
@@ -237,14 +279,15 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
}
}
+ // DCOUT("hit_count: " << hit_count << " miss_count: " << miss_count << " d_counter: " << d_counter);
+
d_counter += to_consume;
+
consume_each(to_consume);
return result;
}
-bool find_sch_burst( const gr_complex *in, const int nitems , gr_complex *out);
-
double gsm_receiver_cf::compute_freq_offset()
{
@@ -252,19 +295,17 @@ double gsm_receiver_cf::compute_freq_offset()
DCOUT(" d_phase_diff_buffer.size(): " << d_phase_diff_buffer.size());
- mean = d_best_sum / FCCH_HITS_NEEDED;
- phase_offset = mean - (M_PI / 2);
+ //mean = d_best_sum / FCCH_HITS_NEEDED;
+ phase_offset = d_best_sum / FCCH_HITS_NEEDED;
+ //phase_offset = mean - ;
freq_offset = phase_offset * 1625000.0 / (12.0 * M_PI);
- DCOUT("freq_offset: " << freq_offset);
+ DCOUT("freq_offset: " << freq_offset << " d_best_sum: " << d_best_sum);
d_fcch_count++;
d_x_temp += freq_offset;
d_x2_temp += freq_offset * freq_offset;
d_mean = d_x_temp / d_fcch_count;
- //d_mean = 0.9 * freq_offset + 0.1 * d_mean;
-
-
- //d_tuner->calleval(freq_offset);
+ set_frequency(freq_offset);
d_prev_freq_offset -= freq_offset;
DCOUT("wariancja: " << sqrt((d_x2_temp / d_fcch_count - d_mean * d_mean)) << " fcch_count:" << d_fcch_count << " d_mean: " << d_mean);
@@ -272,12 +313,92 @@ double gsm_receiver_cf::compute_freq_offset()
return freq_offset;
}
-void gsm_receiver_cf::set_frequency()
+void gsm_receiver_cf::set_frequency(double freq_offset)
{
+ d_tuner->calleval(freq_offset);
+}
+
+bool gsm_receiver_cf::find_sch_burst(const gr_complex *in, const int nitems , float *out)
+{
+ int sample_number = 0;
+ int to_consume = 0;
+ bool end = false;
+ bool result = false;
+ int sch_start = d_fcch_start_pos + FRAME_BITS * d_OSR;
+
+ enum states {
+ init, search, sch_found, search_fail
+ } sch_search_state;
+
+ while (!end) {
+ switch (sch_search_state) {
+ case init:
+ sch_search_state = search_fail;
+ break;
+
+ case search:
+
+ if ((sch_start >= d_counter) && (sch_start <= d_counter + nitems)) {
+ DCOUT("sch_start-d_counter: " << sch_start - d_counter);
+ /* for (int i = 0; i < nitems - N_SYNC_BITS; i++) {
+ gr_complex result = correlation(&d_sch_training_seq[5], in + i, N_SYNC_BITS-10);
+ //std::cout << "(" << real(in[i]) << "," << imag(in[i]) << ")\n";
+ std::cout << "(" << real(result) << "," << imag(result) << ")\n";
+ }
+ std::cout << std::endl;
+ */
+ }
+
+ to_consume = nitems - N_SYNC_BITS;
+
+ sch_search_state = search_fail;
+ break;
+
+ case sch_found:
+ end = true;
+ break;
+
+ case search_fail:
+ end = true;
+ break;
+ }
+ }
+
+ d_counter += to_consume;
+
+// consume_each(to_consume);
+
+ return result;
}
-bool gsm_receiver_cf::find_sch_burst( const gr_complex *in, const int nitems , gr_complex *out)
+void gsm_receiver_cf::gmsk_mapper(const int * input, gr_complex * output, int ninput)
{
-
+ gr_complex j = gr_complex(0.0, 1.0);
+
+ int current_symbol;
+ int encoded_symbol;
+ int previous_symbol = 2 * input[0] - 1;
+ output[0] = gr_complex(1.0, 0.0);
+
+ for (int i = 1; i < ninput; i++) {
+ //change bits representation to NRZ
+ current_symbol = 2 * input[i] - 1;
+ //differentially encode
+ encoded_symbol = current_symbol * previous_symbol;
+ //and do gmsk mapping
+ output[i] = j * gr_complex(encoded_symbol, 0.0) * output[i-1];
+ previous_symbol = current_symbol;
+ }
+}
+
+gr_complex gsm_receiver_cf::correlation(const gr_complex * sequence, const gr_complex * input_signal, int ninput)
+{
+ gr_complex result(0.0, 0.0);
+
+ for (int ii = 1; (ii * d_OSR) <= ninput; ii++) {
+ result += sequence[ii-1] * conj(input_signal[(ii * d_OSR)]);
+ }
+
+ return result;
}
diff --git a/src/lib/gsm_receiver_cf.h b/src/lib/gsm_receiver_cf.h
index 2012325..0e287c5 100644
--- a/src/lib/gsm_receiver_cf.h
+++ b/src/lib/gsm_receiver_cf.h
@@ -26,6 +26,8 @@
#include <gr_complex.h>
#include <gr_feval.h>
#include <boost/circular_buffer.hpp>
+#include <gsm_constants.h>
+
class gsm_receiver_cf;
@@ -51,7 +53,7 @@ typedef boost::circular_buffer<float> circular_buffer_float;
* constructor is private. howto_make_square_ff is the public
* interface for creating new instances.
*/
-gsm_receiver_cf_sptr gsm_make_receiver_cf( gr_feval_dd *tuner, int osr );
+gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr);
/*!
* \brief Receives fcch
@@ -64,34 +66,38 @@ class gsm_receiver_cf : public gr_block
private:
gr_feval_dd *d_tuner;
- const int d_osr;
+ const int d_OSR;
int d_counter;
+ int d_fcch_start_pos;
float d_prev_freq_offset;
circular_buffer_float d_phase_diff_buffer;
double d_x_temp, d_x2_temp, d_mean;
int d_fcch_count;
double d_best_sum;
-
- enum states
- {
+ gr_complex d_sch_training_seq[N_SYNC_BITS]; //encoded training sequence of a SCH burst
+
+
+ enum states {
fcch_search, sch_search
} d_state;
- friend gsm_receiver_cf_sptr gsm_make_receiver_cf( gr_feval_dd *tuner, int osr );
- gsm_receiver_cf( gr_feval_dd *tuner, int osr );
+ friend gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr);
+ gsm_receiver_cf(gr_feval_dd *tuner, int osr);
- bool find_fcch_burst( const gr_complex *in, const int nitems );
- bool find_sch_burst( const gr_complex *in, const int nitems , gr_complex *out);
- double compute_freq_offset ( );
- void set_frequency ( );
+ bool find_fcch_burst(const gr_complex *in, const int nitems);
+ double compute_freq_offset();
+ void set_frequency(double freq_offset);
+ bool find_sch_burst(const gr_complex *in, const int nitems , float *out);
+ void gmsk_mapper(const int * input, gr_complex * gmsk_output, int ninput);
+ gr_complex correlation(const gr_complex * sequence, const gr_complex * input_signal, int ninput);
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,
- gr_vector_void_star &output_items );
+ 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,
+ gr_vector_void_star &output_items);
};
#endif /* INCLUDED_GSM_RECEIVER_CF_H */
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