Added new blocks for clock freqeuncy correction
diff --git a/lib/receiver/receiver_impl.cc b/lib/receiver/receiver_impl.cc
index 500113e..c333ccf 100644
--- a/lib/receiver/receiver_impl.cc
+++ b/lib/receiver/receiver_impl.cc
@@ -71,7 +71,7 @@
d_tuner(tuner),
d_counter(0),
d_fcch_start_pos(0),
- d_freq_offset(0),
+ d_freq_offset_setting(0),
d_state(first_fcch_search),
d_burst_nr(osr),
d_failed_sch(0),
@@ -79,7 +79,7 @@
d_signal_dbm(-120)
{
int i;
- //set_output_multiple(floor((TS_BITS + 2 * GUARD_PERIOD) * d_OSR)); //don't send samples to the receiver until there are at least samples for one
+ //don't send samples to the receiver until there are at least samples for one
set_output_multiple(floor((TS_BITS + 2 * GUARD_PERIOD) * d_OSR)); // burst and two gurad periods (one gurard period is an arbitrary overlap)
gmsk_mapper(SYNC_BITS, N_SYNC_BITS, d_sch_training_seq, gr_complex(0.0, -1.0));
for (i = 0; i < TRAIN_SEQ_NUM; i++)
@@ -89,11 +89,10 @@
gmsk_mapper(train_seq[i], N_TRAIN_BITS, d_norm_training_seq[i], startpoint);
}
message_port_register_out(pmt::mp("bursts"));
+ message_port_register_out(pmt::mp("measurements"));
configure_receiver(); //configure the receiver - tell it where to find which burst type
}
-
-
/*
* Our virtual destructor.
*/
@@ -106,19 +105,44 @@
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
- //std::cout << noutput_items << std::endl;
const gr_complex *input = (const gr_complex *) input_items[0];
+ std::vector<tag_t> freq_offset_tags;
+ uint64_t start = nitems_read(0);
+ uint64_t stop = start + noutput_items;
+ pmt::pmt_t key = pmt::string_to_symbol("setting_freq_offset");
+ get_tags_in_range(freq_offset_tags, 0, start, stop, key);
+ bool freq_offset_tag_in_fcch = false;
+ uint64_t tag_offset=-1; //-1 - just some clearly invalid value
+
+ if(!freq_offset_tags.empty()){
+ tag_t freq_offset_tag = freq_offset_tags[0];
+ tag_offset = freq_offset_tag.offset - start;
+
+ burst_type b_type = d_channel_conf.get_burst_type(d_burst_nr);
+ if(d_state == synchronized && b_type == fcch_burst){
+ uint64_t last_sample_nr = ceil((GUARD_PERIOD + 2.0 * TAIL_BITS + 156.25) * d_OSR) + 1;
+ if(tag_offset < last_sample_nr){
+ DCOUT("Freq change inside FCCH burst!!!!!!!!!!!!!!");
+ freq_offset_tag_in_fcch = true;
+ }
+ d_freq_offset_setting = pmt::to_double(freq_offset_tag.value);
+ } else {
+ d_freq_offset_setting = pmt::to_double(freq_offset_tag.value);
+ }
+ }
+
switch (d_state)
{
//bootstrapping
case first_fcch_search:
DCOUT("FCCH search");
- if (find_fcch_burst(input, noutput_items)) //find frequency correction burst in the input buffer
+ double freq_offset_tmp;
+ if (find_fcch_burst(input, noutput_items, freq_offset_tmp)) //find frequency correction burst in the input buffer
{
- //set_frequency(d_freq_offset); //if fcch search is successful set frequency offset
- DCOUT("Freq offset " << d_freq_offset);
- DCOUT("PPM: " << d_freq_offset/940e6);
+ pmt::pmt_t msg = pmt::make_tuple(pmt::mp("freq_offset"),pmt::from_double(freq_offset_tmp-d_freq_offset_setting),pmt::mp("first_fcch_search"));
+ message_port_pub(pmt::mp("measurements"), msg);
+
d_state = next_fcch_search;
}
else
@@ -130,15 +154,12 @@
case next_fcch_search: //this state is used because it takes some time (a bunch of buffered samples)
{
DCOUT("NEXT FCCH search");
- d_prev_freq_offset = d_freq_offset; //before previous set_frequqency cause change
- if (find_fcch_burst(input, noutput_items))
+ double freq_offset_tmp;
+ if (find_fcch_burst(input, noutput_items,freq_offset_tmp))
{
- if (abs(d_prev_freq_offset - d_freq_offset) > FCCH_MAX_FREQ_OFFSET)
- {
- //set_frequency(d_freq_offset); //call set_frequncy only frequency offset change is greater than some value
- //COUT("Freq offset " << d_freq_offset);
- DCOUT("PPM: " << d_freq_offset/940);
- }
+ pmt::pmt_t msg = pmt::make_tuple(pmt::mp("freq_offset"),pmt::from_double(freq_offset_tmp-d_freq_offset_setting),pmt::mp("next_fcch_search"));
+ message_port_pub(pmt::mp("measurements"), msg);
+
d_state = sch_search;
}
else
@@ -148,7 +169,6 @@
break;
}
-
case sch_search:
{
DCOUT("SCH search");
@@ -206,30 +226,24 @@
{
const unsigned first_sample = ceil((GUARD_PERIOD + 2 * TAIL_BITS) * d_OSR) + 1;
const unsigned last_sample = first_sample + USEFUL_BITS * d_OSR - TAIL_BITS * d_OSR;
- double freq_offset = compute_freq_offset(input, first_sample, last_sample); //extract frequency offset from it
+ double freq_offset_tmp = compute_freq_offset(input, first_sample, last_sample); //extract frequency offset from it
- d_freq_offset_vals.push_front(freq_offset);
send_burst(d_burst_nr, fc_fb, b_type);
- if (d_freq_offset_vals.size() >= 10)
- {
- double sum = std::accumulate(d_freq_offset_vals.begin(), d_freq_offset_vals.end(), 0);
- double mean_offset = sum / d_freq_offset_vals.size(); //compute mean
- d_freq_offset_vals.clear();
- DCOUT("mean offset" << mean_offset/940);
- if (abs(mean_offset) > FCCH_MAX_FREQ_OFFSET)
- {
- //d_freq_offset -= mean_offset; //and adjust frequency if it have changed beyond
- //set_frequency(d_freq_offset); //some limit
- DCOUT("Adjusting frequency, new frequency offset: " << d_freq_offset << "\n");
- }
- }
+ pmt::pmt_t msg = pmt::make_tuple(pmt::mp("freq_offset"),pmt::from_double(freq_offset_tmp-d_freq_offset_setting),pmt::mp("synchronized"));
+ message_port_pub(pmt::mp("measurements"), msg);
}
break;
case sch_burst: //if it's SCH burst
{
int t1, t2, t3, d_ncc, d_bcc;
burst_start = get_sch_chan_imp_resp(input, &channel_imp_resp[0]); //get channel impulse response
+
+ if(d_prev_burst_start != burst_start){
+ d_prev_burst_start = burst_start;
+ DCOUT("burst start" << burst_start);
+ }
+
detect_burst(input, &channel_imp_resp[0], burst_start, output_binary); //MLSE detection of bits
send_burst(d_burst_nr, output_binary, b_type);
if (decode_sch(&output_binary[3], &t1, &t2, &t3, &d_ncc, &d_bcc) == 0) //and decode SCH data
@@ -247,10 +261,9 @@
if (d_failed_sch >= MAX_SCH_ERRORS)
{
d_state = next_fcch_search;
- d_freq_offset_vals.clear();
- d_freq_offset=0;
- //set_frequency(0);
- COUT("Re-Synchronization!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
+ pmt::pmt_t msg = pmt::make_tuple(pmt::mp("freq_offset"),pmt::from_double(0.0),pmt::mp("sync_loss"));
+ message_port_pub(pmt::mp("measurements"), msg);
+ DCOUT("Re-Synchronization!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
}
}
}
@@ -268,9 +281,7 @@
{
unsigned int normal_burst_start;
float dummy_corr_max, normal_corr_max;
- DCOUT("Dummy");
get_norm_chan_imp_resp(input, &channel_imp_resp[0], &dummy_corr_max, TS_DUMMY);
- DCOUT("Normal");
normal_burst_start = get_norm_chan_imp_resp(input, &channel_imp_resp[0], &normal_corr_max, d_bcc);
DCOUT("normal_corr_max: " << normal_corr_max << " dummy_corr_max:" << dummy_corr_max);
@@ -305,8 +316,7 @@
return 0;
}
-
-bool receiver_impl::find_fcch_burst(const gr_complex *input, const int nitems)
+bool receiver_impl::find_fcch_burst(const gr_complex *input, const int nitems, double & computed_freq_offset)
{
circular_buffer_float phase_diff_buffer(FCCH_HITS_NEEDED * d_OSR); //circular buffer used to scan throug signal to find
//best match for FCCH burst
@@ -451,10 +461,8 @@
//compute frequency offset
double phase_offset = best_sum / FCCH_HITS_NEEDED;
- double freq_offset = phase_offset * 1625000.0 / (12.0 * M_PI);
- //d_freq_offset -= freq_offset;
- d_freq_offset = freq_offset;
- DCOUT("freq_offset: " << d_freq_offset);
+ double freq_offset = phase_offset * 1625000.0/6 / (2 * M_PI); //1625000.0/6 - GMSK symbol rate in GSM
+ computed_freq_offset = freq_offset;
end = true;
result = true;
@@ -623,7 +631,6 @@
}
}
-//TODO consider placing this funtion in a separate class for signal processing
void receiver_impl::gmsk_mapper(const unsigned char * input, int nitems, gr_complex * gmsk_output, gr_complex start_point)
{
gr_complex j = gr_complex(0.0, 1.0);
@@ -645,7 +652,6 @@
}
}
-//TODO consider use of some generalized function for correlation and placing it in a separate class for signal processing
gr_complex receiver_impl::correlate_sequence(const gr_complex * sequence, int length, const gr_complex * input)
{
gr_complex result(0.0, 0.0);
@@ -662,7 +668,6 @@
}
//computes autocorrelation for positive arguments
-//TODO consider placing this funtion in a separate class for signal processing
inline void receiver_impl::autocorrelation(const gr_complex * input, gr_complex * out, int nitems)
{
int i, k;
@@ -676,7 +681,6 @@
}
}
-//TODO consider use of some generalized function for filtering and placing it in a separate class for signal processing
inline void receiver_impl::mafi(const gr_complex * input, int nitems, gr_complex * filter, int filter_length, gr_complex * output)
{
int ii = 0, n, a;
@@ -698,7 +702,6 @@
}
}
-//TODO: get_norm_chan_imp_resp is similar to get_sch_chan_imp_resp - consider joining this two functions
//especially computations of strongest_window_nr
int receiver_impl::get_norm_chan_imp_resp(const gr_complex *input, gr_complex * chan_imp_resp, float *corr_max, int bcc)
{
@@ -774,8 +777,6 @@
DCOUT("strongest_window_nr_new: " << strongest_window_nr);
burst_start = search_start_pos + strongest_window_nr - TRAIN_POS * d_OSR; //compute first sample posiiton which corresponds to the first sample of the impulse response
- //TRAIN_POS=3+57+1+6
- //TODO: describe this part in detail in documentation as this is crucial part for synchronization
DCOUT("burst_start: " << burst_start);
return burst_start;
@@ -845,7 +846,6 @@
void receiver_impl::set_arfcn(int arfcn) //!!
{
d_arfcn = arfcn;
-// std::cout << "set arfcn:"<<arfcn << std::endl;
}
void receiver_impl::reset()