diff options
| -rw-r--r-- | src/lib/gsm_constants.h | 1 | ||||
| -rw-r--r-- | src/lib/gsm_receiver_cf.cc | 132 | ||||
| -rw-r--r-- | src/lib/gsm_receiver_cf.h | 22 | ||||
| -rwxr-xr-x | src/python/gsm_findfcch.py | 4 |
4 files changed, 71 insertions, 88 deletions
diff --git a/src/lib/gsm_constants.h b/src/lib/gsm_constants.h index 62dc86b..50ea600 100644 --- a/src/lib/gsm_constants.h +++ b/src/lib/gsm_constants.h @@ -19,6 +19,7 @@ #define FCCH_POS TAIL_BITS #define SYNC_POS 39 #define TRAIN_POS 58 +#define SAFETY_MARGIN 6 #define FCCH_HITS_NEEDED (USEFUL_BITS - 4) #define FCCH_MAX_MISSES 1 diff --git a/src/lib/gsm_receiver_cf.cc b/src/lib/gsm_receiver_cf.cc index 3b0e426..474a9d1 100644 --- a/src/lib/gsm_receiver_cf.cc +++ b/src/lib/gsm_receiver_cf.cc @@ -54,14 +54,14 @@ gsm_receiver_cf::gsm_receiver_cf(gr_feval_dd *tuner, int osr) gr_make_io_signature(MIN_OUT, MAX_OUT, 142 * sizeof(float))), d_OSR(osr), d_tuner(tuner), - d_prev_freq_offset(0), - 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) + d_freq_offset(0), + d_state(first_fcch_search), + d_first(false) + // d_fcch_count(0), + // d_x_temp(0), + // d_x2_temp(0) { gmsk_mapper(SYNC_BITS, d_sch_training_seq, N_SYNC_BITS); } @@ -90,77 +90,56 @@ gsm_receiver_cf::general_work(int noutput_items, switch (d_state) { - case fcch_search: + case first_fcch_search: if (find_fcch_burst(in, ninput_items[0])) { - produced_out = 1; - d_state = sch_search; + set_frequency(d_freq_offset); + produced_out = 0; + d_state = next_fcch_search; } else { produced_out = 0; - d_state = fcch_search; + d_state = first_fcch_search; } break; - case sch_search: - - if (find_sch_burst(in, ninput_items[0], out)) { - + case next_fcch_search: + if (find_fcch_burst(in, ninput_items[0])) { + produced_out = 0; 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]); + produced_out = 0; + d_state = next_fcch_search; + } + break; + case sch_search: + if (find_sch_burst(in, ninput_items[0], out)) { + d_state = read_bcch; + } else { d_state = sch_search; } - + break; + + case read_bcch: break; } -// for (int i = 0; i < TS_BITS; i++) { -// out[i] = d_phase_diff_buffer[i+start_pos-USEFUL_BITS]; -// } - return produced_out; } bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) { + circular_buffer_float phase_diff_buffer(BUFFER_SIZE * d_OSR); + float phase_diff = 0; gr_complex conjprod; int hit_count = 0; int miss_count = 0; - int start_pos; - float min_phase_diff, max_phase_diff, lowest_max_min_diff; + int start_pos = -1; + float min_phase_diff; + float max_phase_diff; + float lowest_max_min_diff = 99999; int to_consume = 0; int sample_number = 0; @@ -183,7 +162,7 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) miss_count = 0; start_pos = -1; lowest_max_min_diff = 99999; - d_phase_diff_buffer.clear(); + phase_diff_buffer.clear(); fcch_search_state = search; break; @@ -196,8 +175,7 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) fcch_search_state = search_fail; } else { - conjprod = in[sample_number] * conj(in[sample_number-1]); - phase_diff = gr_fast_atan2f(imag(conjprod), real(conjprod)); + phase_diff = compute_phase_diff(in[sample_number], in[sample_number-1]); if (phase_diff > 0) { to_consume = sample_number; @@ -228,16 +206,16 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) //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())); + min_phase_diff = *(min_element(phase_diff_buffer.begin(), phase_diff_buffer.end())); + max_phase_diff = *(max_element(phase_diff_buffer.begin(), phase_diff_buffer.end())); if (lowest_max_min_diff > max_phase_diff - min_phase_diff) { lowest_max_min_diff = max_phase_diff - min_phase_diff; 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()); + for (buffer_iter = (phase_diff_buffer.begin()); + buffer_iter != (phase_diff_buffer.end()); buffer_iter++) { d_best_sum += *buffer_iter - (M_PI / 2) / d_OSR; } @@ -251,10 +229,8 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) continue; } - 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); + phase_diff = compute_phase_diff(in[sample_number], in[sample_number-1]); + phase_diff_buffer.push_back(phase_diff); fcch_search_state = found_something; @@ -280,7 +256,11 @@ 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); - + //! + for(int i = 0; i < to_consume; i++){ + //std::cout << "(" << real(in[i]) << "," << imag(in[i]) << ")\n"; + } + d_counter += to_consume; consume_each(to_consume); @@ -291,24 +271,18 @@ bool gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) double gsm_receiver_cf::compute_freq_offset() { - float mean, phase_offset, freq_offset; + float phase_offset, freq_offset; - DCOUT(" d_phase_diff_buffer.size(): " << d_phase_diff_buffer.size()); - - //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 << " 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; - - 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); + d_freq_offset -= freq_offset; + +// d_x_temp += freq_offset; +// d_x2_temp += freq_offset * freq_offset; +// d_mean = d_x_temp / d_fcch_count; +// d_fcch_count++; + DCOUT("freq_offset: " << freq_offset << " d_best_sum: " << d_best_sum); +// DCOUT("wariancja: " << sqrt((d_x2_temp / d_fcch_count - d_mean * d_mean)) << " fcch_count:" << d_fcch_count << " d_mean: " << d_mean); return freq_offset; } diff --git a/src/lib/gsm_receiver_cf.h b/src/lib/gsm_receiver_cf.h index 0e287c5..ccc99fb 100644 --- a/src/lib/gsm_receiver_cf.h +++ b/src/lib/gsm_receiver_cf.h @@ -65,20 +65,25 @@ class gsm_receiver_cf : public gr_block { private: - gr_feval_dd *d_tuner; const int d_OSR; + gr_complex d_sch_training_seq[N_SYNC_BITS]; //encoded training sequence of a SCH burst + + gr_feval_dd *d_tuner; int d_counter; + + //variables used to store result of the find_fcch_burst fuction 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; + float d_freq_offset; double d_best_sum; - gr_complex d_sch_training_seq[N_SYNC_BITS]; //encoded training sequence of a SCH burst + int d_fcch_count; + + bool d_first; +// int d_fcch_count; +// double d_x_temp, d_x2_temp, d_mean; enum states { - fcch_search, sch_search + first_fcch_search, next_fcch_search, sch_search, read_bcch } d_state; friend gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr); @@ -87,9 +92,12 @@ class gsm_receiver_cf : public gr_block bool find_fcch_burst(const gr_complex *in, const int nitems); double compute_freq_offset(); void set_frequency(double freq_offset); + inline float compute_phase_diff(gr_complex val1, gr_complex val2); + 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(); diff --git a/src/python/gsm_findfcch.py b/src/python/gsm_findfcch.py index 9c0620b..09615bf 100755 --- a/src/python/gsm_findfcch.py +++ b/src/python/gsm_findfcch.py @@ -18,8 +18,8 @@ class tune(gr.feval_dd): self.top_block = top_block self.center_freq = 0 def eval(self, freq_offet): - self.center_freq = self.center_freq - freq_offet - self.top_block.set_frequency(self.center_freq) +# self.center_freq = self.center_freq - freq_offet + self.top_block.set_frequency(freq_offet) return self.center_freq |