diff options
Diffstat (limited to 'src/lib/gsm_receiver_cf.cc')
| -rw-r--r-- | src/lib/gsm_receiver_cf.cc | 257 |
1 files changed, 196 insertions, 61 deletions
diff --git a/src/lib/gsm_receiver_cf.cc b/src/lib/gsm_receiver_cf.cc index 206bd5e..4f43f2b 100644 --- a/src/lib/gsm_receiver_cf.cc +++ b/src/lib/gsm_receiver_cf.cc @@ -27,14 +27,18 @@ #include <gsm_receiver_cf.h> #include <gr_io_signature.h> #include <gr_math.h> +#include <math.h> #include <gsm_constants.h> #include <Assert.h> +#include <algorithm> +#define SAFETY_MARGIN 50 +#define BUFFER_SIZE (FCCH_HITS_NEEDED) gsm_receiver_cf_sptr -gsm_make_receiver_cf(int osr) +gsm_make_receiver_cf(gr_feval_dd *tuner, int osr) { - return gsm_receiver_cf_sptr(new gsm_receiver_cf(osr)); + return gsm_receiver_cf_sptr(new gsm_receiver_cf(tuner, osr)); } static const int MIN_IN = 1; // mininum number of input streams @@ -45,11 +49,19 @@ static const int MAX_OUT = 1; // maximum number of output streams /* * The private constructor */ -gsm_receiver_cf::gsm_receiver_cf(int osr) +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_counter(0) + d_osr(osr), + d_tuner(tuner), + d_prev_freq_offset(0), + d_phase_diff_buffer(BUFFER_SIZE), + d_counter(0), + d_x_temp(0), + d_x2_temp(0), + d_fcch_count(0), + d_state(fcch_search) { } @@ -73,76 +85,199 @@ 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; -// DCOUT(ninput_items[0]); -// DCOUT(noutput_items); + switch (d_state) { + case fcch_search: - 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]; + if (find_fcch_burst(in, ninput_items[0])) { + produced_out = 1; + d_state = fcch_search; + } else { + produced_out = 0; + d_state = fcch_search; + } + + break; + + case sch_search: + break; } - consume_each(start_pos); - d_counter += start_pos; - return d_return; + +// for (int i = 0; i < TS_BITS; i++) { +// out[i] = d_phase_diff_buffer[i+start_pos-USEFUL_BITS]; +// } + + return produced_out; } -int gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems) +bool 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; - } + float phase_diff = 0; + gr_complex conjprod; + int hit_count, miss_count, start_pos; + float min_phase_diff, max_phase_diff, lowest_max_min_diff; + float sum, best_sum; - int hit_count = 0; - int miss_count = 0; - int start_pos = -1; + int to_consume = 0; + int i = 0; + bool end = false; + bool result; - d_return = 0;//! - - for (int i = 0; ; i++) { - if (i > nitems - USEFUL_BITS - 1) { - start_pos = nitems - USEFUL_BITS - 1; - break; - } + circular_buffer_float::iterator buffer_iter; - 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; + enum states { + init, search, found_something, fcch_found, search_fail + } fcch_search_state; + + fcch_search_state = init; + + while ((!end) && (i < nitems)) { + switch (fcch_search_state) { + + case init: + hit_count = 0; + miss_count = 0; + start_pos = -1; + lowest_max_min_diff = 99999; + d_phase_diff_buffer.clear(); + fcch_search_state = search; + + break; + + case search: + i++; + + if (i > nitems - BUFFER_SIZE) { + to_consume = i; + fcch_search_state = search_fail; + } + + conjprod = in[i] * conj(in[i-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; + } + + break; + + case found_something: + + if (phase_diff > 0) { + hit_count++; + } else { + 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)) { + fcch_search_state = init; + continue; + } else if ((miss_count >= FCCH_MAX_MISSES) && (hit_count > FCCH_HITS_NEEDED)) { + fcch_search_state = fcch_found; + continue; + } else if ((miss_count < FCCH_MAX_MISSES) && (hit_count > FCCH_HITS_NEEDED)) { + //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){ + lowest_max_min_diff = max_phase_diff - min_phase_diff; + start_pos = i - FCCH_HITS_NEEDED; + 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; + } + DCOUT(d_best_sum); + } + } + + i++; + + if (i >= nitems) { + fcch_search_state = search_fail; + continue; + } + + conjprod = in[i] * conj(in[i-1]); + phase_diff = gr_fast_atan2f(imag(conjprod), real(conjprod)); + d_phase_diff_buffer.push_back(phase_diff); + + fcch_search_state = found_something; + + break; + + case fcch_found: + DCOUT("znalezione fcch na pozycji" << d_counter + start_pos); + to_consume = start_pos + FCCH_HITS_NEEDED + 1; + /* mean = d_best_sum / FCCH_HITS_NEEDED; + phase_offset = mean - (M_PI / 2); + freq_offset = phase_offset * 1625000.0 / (12.0 * M_PI);*/ + compute_freq_offset(); + end = true; + result = true; + break; + + case search_fail: + end = true; + result = false; + break; } } - /* - //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); - } - } else { - //Didn't find anything - d_burst_start = MAX_CORR_DIST; - d_bbuf_pos = 0; //load buffer from start - } - */ - //DCOUT("start_pos: " << start_pos); + 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() +{ + float mean, phase_offset, 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); + freq_offset = phase_offset * 1625000.0 / (12.0 * M_PI); + DCOUT("freq_offset: " << freq_offset); + 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); + + 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); - return start_pos; + return freq_offset; } +void gsm_receiver_cf::set_frequency() +{ + +} + +bool gsm_receiver_cf::find_sch_burst( const gr_complex *in, const int nitems , gr_complex *out) +{ + +} |