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Added configuration option to customize the extension of the GPS L1 CA correlation length after bit synchronization (options are: [1,2,4,5,10,20] ms). Increasing resolution in CN0 estimator internal variables.

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This commit is contained in:
Javier Arribas 2016-03-16 17:32:20 +01:00
parent 6c2f3d8f43
commit 2f61ad7c64
4 changed files with 43 additions and 25 deletions
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4
src/algorithms/tracking/adapters/gps_l1_ca_dll_pll_c_aid_tracking.cc
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@ -73,6 +73,9 @@ GpsL1CaDllPllCAidTracking::GpsL1CaDllPllCAidTracking(
dll_bw_hz = configuration->property(role + ".dll_bw_hz", 2.0);
pll_bw_narrow_hz = configuration->property(role + ".pll_bw_narrow_hz", 20.0);
dll_bw_narrow_hz = configuration->property(role + ".dll_bw_narrow_hz", 2.0);
int extend_correlation_ms;
extend_correlation_ms = configuration->property(role + ".extend_correlation_ms", 1);
early_late_space_chips = configuration->property(role + ".early_late_space_chips", 0.5);
std::string default_dump_filename = "./track_ch";
dump_filename = configuration->property(role + ".dump_filename",
@ -94,6 +97,7 @@ GpsL1CaDllPllCAidTracking::GpsL1CaDllPllCAidTracking(
dll_bw_hz,
pll_bw_narrow_hz,
dll_bw_narrow_hz,
extend_correlation_ms,
early_late_space_chips);
DLOG(INFO) << "tracking(" << tracking_cc->unique_id() << ")";
}else if(item_type_.compare("cshort") == 0)

37
src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_c_aid_tracking_cc.cc
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@ -69,10 +69,11 @@ gps_l1_ca_dll_pll_c_aid_make_tracking_cc(
float dll_bw_hz,
float pll_bw_narrow_hz,
float dll_bw_narrow_hz,
int extend_correlation_ms,
float early_late_space_chips)
{
return gps_l1_ca_dll_pll_c_aid_tracking_cc_sptr(new gps_l1_ca_dll_pll_c_aid_tracking_cc(if_freq,
fs_in, vector_length, queue, dump, dump_filename, pll_bw_hz, dll_bw_hz,pll_bw_narrow_hz, dll_bw_narrow_hz, early_late_space_chips));
fs_in, vector_length, queue, dump, dump_filename, pll_bw_hz, dll_bw_hz,pll_bw_narrow_hz, dll_bw_narrow_hz, extend_correlation_ms, early_late_space_chips));
}
@ -90,10 +91,10 @@ void gps_l1_ca_dll_pll_c_aid_tracking_cc::msg_handler_preamble_index(pmt::pmt_t
{
//pmt::print(msg);
DLOG(INFO) << "Extended correlation for Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)<< std::endl;
if (d_enable_20ms_integration==false) //avoid re-setting preamble indicator
if (d_enable_extended_integration==false) //avoid re-setting preamble indicator
{
d_preamble_index=pmt::to_long(msg);
d_enable_20ms_integration=true;
d_enable_extended_integration=true;
d_preamble_synchronized=false;
}
}
@ -110,6 +111,7 @@ gps_l1_ca_dll_pll_c_aid_tracking_cc::gps_l1_ca_dll_pll_c_aid_tracking_cc(
float dll_bw_hz,
float pll_bw_narrow_hz,
float dll_bw_narrow_hz,
int extend_correlation_ms,
float early_late_space_chips) :
gr::block("gps_l1_ca_dll_pll_c_aid_tracking_cc", gr::io_signature::make(1, 1, sizeof(gr_complex)),
gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)))
@ -135,6 +137,7 @@ gps_l1_ca_dll_pll_c_aid_tracking_cc::gps_l1_ca_dll_pll_c_aid_tracking_cc(
d_dll_bw_hz=dll_bw_hz;
d_pll_bw_narrow_hz=pll_bw_narrow_hz;
d_dll_bw_narrow_hz=dll_bw_narrow_hz;
d_extend_correlation_ms = extend_correlation_ms;
d_code_loop_filter.set_DLL_BW(d_dll_bw_hz);
d_carrier_loop_filter.set_params(10.0, d_pll_bw_hz,2);
@ -206,7 +209,7 @@ gps_l1_ca_dll_pll_c_aid_tracking_cc::gps_l1_ca_dll_pll_c_aid_tracking_cc(
d_rem_code_phase_chips = 0.0;
d_code_phase_step_chips = 0.0;
d_carrier_phase_step_rad = 0.0;
d_enable_20ms_integration=false;
d_enable_extended_integration=false;
d_preamble_synchronized=false;
//set_min_output_buffer((long int)300);
}
@ -291,7 +294,7 @@ void gps_l1_ca_dll_pll_c_aid_tracking_cc::start_tracking()
// enable tracking
d_pull_in = true;
d_enable_tracking = true;
d_enable_20ms_integration=false;
d_enable_extended_integration=false;
d_preamble_synchronized=false;
LOG(INFO) << "PULL-IN Doppler [Hz]=" << d_carrier_doppler_hz
<< " Code Phase correction [samples]=" << delay_correction_samples
@ -364,7 +367,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
d_P_history.push_back(d_correlator_outs[1]); // save prompt output
d_L_history.push_back(d_correlator_outs[2]); // save late output
if (d_P_history.size()>GPS_CA_TELEMETRY_SYMBOLS_PER_BIT)
if (d_P_history.size()>d_extend_correlation_ms)
{
d_E_history.pop_front();
d_P_history.pop_front();
@ -372,10 +375,10 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
}
bool enable_dll_pll;
if (d_enable_20ms_integration==true)
if (d_enable_extended_integration==true)
{
long int symbol_diff=d_symbol_counter-d_preamble_index;
if (symbol_diff % GPS_CA_TELEMETRY_SYMBOLS_PER_BIT == 0)
if (symbol_diff % d_extend_correlation_ms == 0)
{
// compute coherent integration and enable tracking loop
// perform coherent integration using correlator output history
@ -384,7 +387,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
d_correlator_outs[0]=gr_complex(0.0,0.0);
d_correlator_outs[1]=gr_complex(0.0,0.0);
d_correlator_outs[2]=gr_complex(0.0,0.0);
for (int n=0;n<GPS_CA_TELEMETRY_SYMBOLS_PER_BIT;n++)
for (int n=0;n<d_extend_correlation_ms;n++)
{
d_correlator_outs[0]+=d_E_history.at(n);
d_correlator_outs[1]+=d_P_history.at(n);
@ -401,7 +404,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
}
current_synchro_data.symbol_integration_enabled=true;
// UPDATE INTEGRATION TIME
CURRENT_INTEGRATION_TIME_S = static_cast<double>(GPS_CA_TELEMETRY_SYMBOLS_PER_BIT)*GPS_L1_CA_CODE_PERIOD;
CURRENT_INTEGRATION_TIME_S = static_cast<double>(d_extend_correlation_ms)*GPS_L1_CA_CODE_PERIOD;
enable_dll_pll=true;
@ -410,6 +413,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
if(d_preamble_synchronized==true)
{
// continue extended coherent correlation
//TODO: Take into account the extended correlation to update the accumulated carrier phase for carrier phase observables!!
//remnant carrier phase [rads]
d_rem_carrier_phase_rad = fmod(d_rem_carrier_phase_rad + d_carrier_phase_step_rad * static_cast<double>(d_correlation_length_samples), GPS_TWO_PI);
@ -523,8 +527,13 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
{
d_cn0_estimation_counter = 0;
// Code lock indicator
d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES, d_fs_in, GPS_L1_CA_CODE_LENGTH_CHIPS);
// Carrier lock indicator
if (current_synchro_data.symbol_integration_enabled==false)
{
d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES, d_fs_in, GPS_L1_CA_CODE_LENGTH_CHIPS);
}else{
d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES, d_fs_in, GPS_L1_CA_CODE_LENGTH_CHIPS*d_extend_correlation_ms);
}
// Carrier lock indicator
d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES);
// Loss of lock detection
if (d_carrier_lock_test < d_carrier_lock_threshold or d_CN0_SNV_dB_Hz < MINIMUM_VALID_CN0)
@ -588,7 +597,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
{
d_last_seg = floor(d_sample_counter / d_fs_in);
std::cout << "Current input signal time = " << d_last_seg << " [s]" << std::endl;
DLOG(INFO) << "GPS L1 C/A Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)
std::cout << "GPS L1 C/A Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)
<< ", CN0 = " << d_CN0_SNV_dB_Hz << " [dB-Hz]" << std::endl;
//if (d_last_seg==5) d_carrier_lock_fail_counter=500; //DEBUG: force unlock!
}
@ -598,7 +607,7 @@ int gps_l1_ca_dll_pll_c_aid_tracking_cc::general_work (int noutput_items, gr_vec
if (floor(d_sample_counter / d_fs_in) != d_last_seg)
{
d_last_seg = floor(d_sample_counter / d_fs_in);
DLOG(INFO) << "Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)
std::cout << "Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)
<< ", CN0 = " << d_CN0_SNV_dB_Hz << " [dB-Hz]";
}
}

6
src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_c_aid_tracking_cc.h
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@ -67,6 +67,7 @@ gps_l1_ca_dll_pll_c_aid_make_tracking_cc(long if_freq,
float dll_bw_hz,
float pll_bw_narrow_hz,
float dll_bw_narrow_hz,
int extend_correlation_ms,
float early_late_space_chips);
@ -101,6 +102,7 @@ private:
float dll_bw_hz,
float pll_bw_narrow_hz,
float dll_bw_narrow_hz,
int extend_correlation_ms,
float early_late_space_chips);
gps_l1_ca_dll_pll_c_aid_tracking_cc(long if_freq,
@ -113,6 +115,7 @@ private:
float dll_bw_hz,
float pll_bw_narrow_hz,
float dll_bw_narrow_hz,
int extend_correlation_ms,
float early_late_space_chips);
// tracking configuration vars
@ -173,7 +176,8 @@ private:
std::deque<gr_complex> d_L_history;
long int d_preamble_index;
long int d_symbol_counter;
bool d_enable_20ms_integration;
int d_extend_correlation_ms;
bool d_enable_extended_integration;
bool d_preamble_synchronized;
int d_correlation_symbol_counter;
void msg_handler_preamble_index(pmt::pmt_t msg);

21
src/algorithms/tracking/libs/lock_detectors.cc
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@ -67,21 +67,22 @@
*/
float cn0_svn_estimator(gr_complex* Prompt_buffer, int length, long fs_in, double code_length)
{
float SNR = 0;
float SNR_dB_Hz = 0;
float Psig = 0;
float Ptot = 0;
double SNR = 0;
double SNR_dB_Hz = 0;
double Psig = 0;
double Ptot = 0;
for (int i=0; i<length; i++)
{
Psig += std::abs(Prompt_buffer[i].real());
Ptot += Prompt_buffer[i].imag() * Prompt_buffer[i].imag() + Prompt_buffer[i].real() * Prompt_buffer[i].real();
Psig += std::abs(static_cast<double>(Prompt_buffer[i].real()));
Ptot += static_cast<double>(Prompt_buffer[i].imag()) * static_cast<double>(Prompt_buffer[i].imag())
+ static_cast<double>(Prompt_buffer[i].real()) * static_cast<double>(Prompt_buffer[i].real());
}
Psig = Psig / (float)length;
Psig = Psig / static_cast<double>(length);
Psig = Psig * Psig;
Ptot = Ptot / (float)length;
Ptot = Ptot / static_cast<double>(length);
SNR = Psig / (Ptot - Psig);
SNR_dB_Hz = 10 * log10(SNR) + 10 * log10(fs_in/2) - 10 * log10((float)code_length);
return SNR_dB_Hz;
SNR_dB_Hz = 10 * log10(SNR) + 10 * log10(static_cast<double>(fs_in)/2) - 10 * log10(code_length);
return static_cast<float>(SNR_dB_Hz);
}