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Fix GPS L1 CA KF to work in extended correlation time

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This commit is contained in:
Javier Arribas 2020-10-21 16:24:52 +02:00
parent 856859af01
commit 09d02a377c
4 changed files with 127 additions and 64 deletions
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156
src/algorithms/tracking/gnuradio_blocks/kf_vtl_tracking.cc
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@ -536,16 +536,6 @@ kf_vtl_tracking::kf_vtl_tracking(const Kf_Conf &conf_) : gr::block("kf_vtl_track
d_rem_code_phase_chips = 0.0;
d_state = 0; // initial state: standby
clear_tracking_vars();
if (d_trk_parameters.smoother_length > 0)
{
d_carr_ph_history.set_capacity(d_trk_parameters.smoother_length * 2);
d_code_ph_history.set_capacity(d_trk_parameters.smoother_length * 2);
}
else
{
d_carr_ph_history.set_capacity(1);
d_code_ph_history.set_capacity(1);
}
d_dump = d_trk_parameters.dump;
d_dump_mat = d_trk_parameters.dump_mat and d_dump;
@ -626,8 +616,8 @@ void kf_vtl_tracking::msg_handler_pvt_to_trk(const pmt::pmt_t &msg)
if (pmt::any_ref(msg).type().hash_code() == typeid(const std::shared_ptr<TrackingCmd>).hash_code())
{
const std::shared_ptr<TrackingCmd> cmd = boost::any_cast<const std::shared_ptr<TrackingCmd>>(pmt::any_ref(msg));
std::cout << "RX pvt-to-trk cmd with delay: "
<< static_cast<double>(nitems_read(0) - cmd->sample_counter) / d_trk_parameters.fs_in << " [s]\n";
// std::cout << "RX pvt-to-trk cmd with delay: "
// << static_cast<double>(nitems_read(0) - cmd->sample_counter) / d_trk_parameters.fs_in << " [s]\n";
}
else
{
@ -652,8 +642,6 @@ void kf_vtl_tracking::start_tracking()
d_carrier_doppler_kf_hz = d_acq_carrier_doppler_hz;
d_carrier_phase_step_rad = TWO_PI * d_carrier_doppler_kf_hz / d_trk_parameters.fs_in;
d_carrier_phase_rate_step_rad = 0.0;
d_carr_ph_history.clear();
d_code_ph_history.clear();
std::array<char, 3> Signal_{};
Signal_[0] = d_acquisition_gnss_synchro->Signal[0];
Signal_[1] = d_acquisition_gnss_synchro->Signal[1];
@ -883,8 +871,11 @@ void kf_vtl_tracking::init_kf(double acq_code_phase_chips, double acq_doppler_hz
// measurement covariance matrix (static)
R = arma::mat(2, 2);
R << Sigma2_Tau << 0 << arma::endr
<< 0 << Sigma2_Phase << arma::endr;
// R << Sigma2_Tau << 0 << arma::endr
// << 0 << Sigma2_Phase << arma::endr;
R << pow(d_trk_parameters.code_disc_sd_chips, 2.0) << 0 << arma::endr
<< 0 << pow(d_trk_parameters.carrier_disc_sd_rads, 2.0) << arma::endr;
//system covariance matrix (static)
Q = arma::mat(5, 5);
@ -917,6 +908,65 @@ void kf_vtl_tracking::init_kf(double acq_code_phase_chips, double acq_doppler_hz
// std::cout << "P: " << P_old_old << "\n";
// std::cout << "x: " << x_old_old << "\n";
}
void kf_vtl_tracking::update_kf_narrow_intgration_time()
{
//Kalman Filter class variables
double Ti = d_current_correlation_time_s;
std::cout << "Ti:" << Ti << std::endl;
// state vector: code_phase_chips, carrier_phase_rads, carrier_freq_hz,carrier_freq_rate_hz, code_freq_chips_s
F << 1 << 0 << 0 << 0 << Ti << arma::endr
<< 0 << 1 << 2.0 * GNSS_PI * Ti << GNSS_PI * (Ti * Ti) << 0 << arma::endr
<< 0 << 0 << 1 << Ti << 0 << arma::endr
<< 0 << 0 << 0 << 1 << 0 << arma::endr
<< 0 << 0 << 0 << 0 << 1 << arma::endr;
double B = d_code_chip_rate / d_signal_carrier_freq; //carrier to code rate factor
H << 1 << 0 << -B * Ti / 2.0 << B * (Ti * Ti) / 6.0 << 0 << arma::endr
<< 0 << 1 << -GNSS_PI * Ti << GNSS_PI * (Ti * Ti) / 3.0 << 0 << arma::endr;
// Phase noise variance
double CN0_lin = pow(10.0, d_trk_parameters.expected_cn0_dbhz / 10.0); // CN0 in Hz
double N_periods = 1; // Only 1 interval
double Sigma2_Tau = 0.25 * (1.0 + 2.0 * CN0_lin * Ti) / (N_periods * pow(CN0_lin * Ti, 2.0)) * (1.0 + (1.0 + 2.0 * CN0_lin * Ti) / (pow(N_periods * (CN0_lin * Ti), 2.0)));
double Sigma2_Phase = 1.0 / (2.0 * CN0_lin * Ti) * (1.0 + 1.0 / (2.0 * CN0_lin * Ti));
// measurement covariance matrix (static)
R << pow(d_trk_parameters.code_disc_sd_chips, 2.0) << 0 << arma::endr
<< 0 << pow(d_trk_parameters.carrier_disc_sd_rads, 2.0) << arma::endr;
//system covariance matrix (static)
Q << pow(d_trk_parameters.narrow_code_phase_sd_chips, 2.0) << 0 << 0 << 0 << 0 << arma::endr
<< 0 << pow(d_trk_parameters.narrow_carrier_phase_sd_rad, 2.0) << 0 << 0 << 0 << arma::endr
<< 0 << 0 << pow(d_trk_parameters.narrow_carrier_freq_sd_hz, 2.0) << 0 << 0 << arma::endr
<< 0 << 0 << 0 << pow(d_trk_parameters.narrow_carrier_freq_rate_sd_hz_s, 2.0) << 0 << arma::endr
<< 0 << 0 << 0 << 0 << pow(d_trk_parameters.narrow_code_rate_sd_chips_s, 2.0) << arma::endr;
}
void kf_vtl_tracking::update_kf_cn0(double current_cn0_dbhz)
{
//Kalman Filter class variables
double Ti = d_correlation_length_ms * 0.001;
double B = d_code_chip_rate / d_signal_carrier_freq; //carrier to code rate factor
H = arma::mat(2, 5);
H << 1 << 0 << -B * Ti / 2.0 << B * (Ti * Ti) / 6.0 << 0 << arma::endr
<< 0 << 1 << -GNSS_PI * Ti << GNSS_PI * (Ti * Ti) / 3.0 << 0 << arma::endr;
// Phase noise variance
double CN0_lin = pow(10.0, current_cn0_dbhz / 10.0); // CN0 in Hz
double N_periods = 1; // Only 1 interval
double Sigma2_Tau = 0.25 * (1.0 + 2.0 * CN0_lin * Ti) / (N_periods * pow(CN0_lin * Ti, 2.0)) * (1.0 + (1.0 + 2.0 * CN0_lin * Ti) / (pow(N_periods * (CN0_lin * Ti), 2.0)));
double Sigma2_Phase = 1.0 / (2.0 * CN0_lin * Ti) * (1.0 + 1.0 / (2.0 * CN0_lin * Ti));
// measurement covariance matrix (static)
R = arma::mat(2, 2);
R << Sigma2_Tau << 0 << arma::endr
<< 0 << Sigma2_Phase << arma::endr;
}
kf_vtl_tracking::~kf_vtl_tracking()
{
if (d_dump_file.is_open())
@ -1144,7 +1194,6 @@ void kf_vtl_tracking::run_Kf()
//std::cout << "d_CN0_SNV_dB_Hz: " << this->d_CN0_SNV_dB_Hz << '\n';
// New code Doppler frequency estimation
//todo: check error signs
if (d_trk_parameters.carrier_aiding)
{
//estimate the code rate exclusively based on the carrier Doppler
@ -1165,8 +1214,11 @@ void kf_vtl_tracking::run_Kf()
// }
// }
// prepare data for next KF epoch
// correct code and carrier phase
d_rem_code_phase_samples += d_trk_parameters.fs_in * d_code_error_kf_chips / d_code_freq_kf_chips_s;
d_rem_carr_phase_rad = d_carrier_phase_kf_rad;
// prepare data for next KF epoch
x_old_old = x_new_new;
P_old_old = P_new_new;
}
@ -1199,11 +1251,9 @@ void kf_vtl_tracking::clear_tracking_vars()
d_Prompt_circular_buffer.clear();
d_carrier_phase_rate_step_rad = 0.0;
d_code_phase_rate_step_chips = 0.0;
d_carr_ph_history.clear();
d_code_ph_history.clear();
}
//todo: IT DOES NOT WORK WHEN NO KF IS RUNNING (extended correlation epochs!!)
void kf_vtl_tracking::update_tracking_vars()
{
d_T_chip_seconds = 1.0 / d_code_freq_kf_chips_s;
@ -1213,32 +1263,24 @@ void kf_vtl_tracking::update_tracking_vars()
// keep alignment parameters for the next input buffer
// Compute the next buffer length based in the new period of the PRN sequence and the code phase error estimation
d_T_prn_samples = d_T_prn_seconds * d_trk_parameters.fs_in;
d_K_blk_samples = d_T_prn_samples + d_rem_code_phase_samples + d_trk_parameters.fs_in * d_code_error_kf_chips / d_code_freq_kf_chips_s;
//d_K_blk_samples = d_T_prn_samples + d_rem_code_phase_samples + d_trk_parameters.fs_in * d_code_error_kf_chips / d_code_freq_kf_chips_s;
//KF will update d_rem_code_phase_samples
d_K_blk_samples = d_T_prn_samples + d_rem_code_phase_samples;
d_current_prn_length_samples = static_cast<int32_t>(std::floor(d_K_blk_samples)); // round to a discrete number of samples
// ################### PLL COMMANDS #################################################
// carrier phase step (NCO phase increment per sample) [rads/sample]
d_carrier_phase_step_rad = TWO_PI * d_carrier_doppler_kf_hz / d_trk_parameters.fs_in;
d_rem_carr_phase_rad = d_carrier_phase_kf_rad;
//d_rem_carr_phase_rad = d_carrier_phase_kf_rad;
// remnant carrier phase to prevent overflow in the code NCO
d_rem_carr_phase_rad += static_cast<float>(d_carrier_phase_step_rad * static_cast<double>(d_current_prn_length_samples) + 0.5 * d_carrier_phase_rate_step_rad * static_cast<double>(d_current_prn_length_samples) * static_cast<double>(d_current_prn_length_samples));
d_rem_carr_phase_rad = fmod(d_rem_carr_phase_rad, TWO_PI);
// carrier phase rate step (NCO phase increment rate per sample) [rads/sample^2]
if (d_trk_parameters.high_dyn)
{
d_carr_ph_history.push_back(std::pair<double, double>(d_carrier_phase_step_rad, static_cast<double>(d_current_prn_length_samples)));
if (d_carr_ph_history.full())
{
double tmp_cp1 = 0.0;
double tmp_cp2 = 0.0;
double tmp_samples = 0.0;
for (unsigned int k = 0; k < d_trk_parameters.smoother_length; k++)
{
tmp_cp1 += d_carr_ph_history[k].first;
tmp_cp2 += d_carr_ph_history[d_trk_parameters.smoother_length * 2 - k - 1].first;
tmp_samples += d_carr_ph_history[d_trk_parameters.smoother_length * 2 - k - 1].second;
}
tmp_cp1 /= static_cast<double>(d_trk_parameters.smoother_length);
tmp_cp2 /= static_cast<double>(d_trk_parameters.smoother_length);
d_carrier_phase_rate_step_rad = (tmp_cp2 - tmp_cp1) / tmp_samples;
}
d_carrier_phase_rate_step_rad = TWO_PI * d_carrier_doppler_rate_kf_hz_s / d_trk_parameters.fs_in;
}
// std::cout << d_carrier_phase_rate_step_rad * d_trk_parameters.fs_in * d_trk_parameters.fs_in / TWO_PI << '\n';
// remnant carrier phase to prevent overflow in the code NCO
@ -1254,25 +1296,12 @@ void kf_vtl_tracking::update_tracking_vars()
// ################### DLL COMMANDS #################################################
// code phase step (Code resampler phase increment per sample) [chips/sample]
d_code_phase_step_chips = d_code_freq_kf_chips_s / d_trk_parameters.fs_in;
if (d_trk_parameters.high_dyn)
{
d_code_ph_history.push_back(std::pair<double, double>(d_code_phase_step_chips, static_cast<double>(d_current_prn_length_samples)));
if (d_code_ph_history.full())
{
double tmp_cp1 = 0.0;
double tmp_cp2 = 0.0;
double tmp_samples = 0.0;
for (unsigned int k = 0; k < d_trk_parameters.smoother_length; k++)
{
tmp_cp1 += d_code_ph_history[k].first;
tmp_cp2 += d_code_ph_history[d_trk_parameters.smoother_length * 2 - k - 1].first;
tmp_samples += d_code_ph_history[d_trk_parameters.smoother_length * 2 - k - 1].second;
}
tmp_cp1 /= static_cast<double>(d_trk_parameters.smoother_length);
tmp_cp2 /= static_cast<double>(d_trk_parameters.smoother_length);
d_code_phase_rate_step_chips = (tmp_cp2 - tmp_cp1) / tmp_samples;
}
}
//todo: extend kf to estimate code rate
// if (d_trk_parameters.high_dyn)
// {
// d_code_phase_rate_step_chips = d_code_freq_kf_rate_chips_s / d_trk_parameters.fs_in;
// }
// remnant code phase [chips]
d_rem_code_phase_samples = d_K_blk_samples - static_cast<double>(d_current_prn_length_samples); // rounding error < 1 sample
d_rem_code_phase_chips = d_code_freq_kf_chips_s * d_rem_code_phase_samples / d_trk_parameters.fs_in;
@ -1918,9 +1947,7 @@ int kf_vtl_tracking::general_work(int noutput_items __attribute__((unused)), gr_
<< d_channel
<< " for satellite " << Gnss_Satellite(d_systemName, d_acquisition_gnss_synchro->PRN) << '\n';
// Set narrow taps delay values [chips]
// d_code_loop_filter.set_update_interval(static_cast<float>(d_current_correlation_time_s));
// d_code_loop_filter.set_noise_bandwidth(d_trk_parameters.dll_bw_narrow_hz);
// d_carrier_loop_filter.set_params(d_trk_parameters.fll_bw_hz, d_trk_parameters.pll_bw_narrow_hz, d_trk_parameters.pll_filter_order);
update_kf_narrow_intgration_time();
if (d_veml)
{
d_local_code_shift_chips[0] = -d_trk_parameters.very_early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
@ -2001,6 +2028,13 @@ int kf_vtl_tracking::general_work(int noutput_items __attribute__((unused)), gr_
}
else
{
if (d_trk_parameters.use_estimated_cn0 == true)
{
if (d_CN0_SNV_dB_Hz > 0)
{
update_kf_cn0(d_CN0_SNV_dB_Hz);
}
}
run_Kf();
update_tracking_vars();
check_carrier_phase_coherent_initialization();

9
src/algorithms/tracking/gnuradio_blocks/kf_vtl_tracking.h
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@ -78,11 +78,14 @@ private:
explicit kf_vtl_tracking(const Kf_Conf &conf_);
void init_kf(double acq_code_phase_chips, double acq_doppler_hz);
void update_kf_narrow_intgration_time();
void update_kf_cn0(double current_cn0_dbhz);
void run_Kf();
void msg_handler_telemetry_to_trk(const pmt::pmt_t &msg);
void msg_handler_pvt_to_trk(const pmt::pmt_t &msg);
void do_correlation_step(const gr_complex *input_samples);
void run_Kf();
void check_carrier_phase_coherent_initialization();
void update_tracking_vars();
void clear_tracking_vars();
@ -109,8 +112,8 @@ private:
volk_gnsssdr::vector<gr_complex> d_Prompt_Data;
volk_gnsssdr::vector<gr_complex> d_Prompt_buffer;
boost::circular_buffer<std::pair<double, double>> d_code_ph_history;
boost::circular_buffer<std::pair<double, double>> d_carr_ph_history;
//boost::circular_buffer<std::pair<double, double>> d_code_ph_history;
boost::circular_buffer<gr_complex> d_Prompt_circular_buffer;
const size_t int_type_hash_code = typeid(int).hash_code();

13
src/algorithms/tracking/libs/kf_conf.cc
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@ -130,6 +130,10 @@ void Kf_Conf::SetFromConfiguration(const ConfigurationInterface *configuration,
//Measurement covariances (R)
expected_cn0_dbhz = configuration->property(role + ".expected_cn0_dbhz", 42.0);
code_disc_sd_chips = configuration->property(role + ".code_disc_sd_chips", 0.01);
carrier_disc_sd_rads = configuration->property(role + ".carrier_disc_sd_rads", 0.1);
enable_dynamic_measurement_covariance = configuration->property(role + ".enable_dynamic_measurement_covariance", false);
use_estimated_cn0 = configuration->property(role + ".use_estimated_cn0", false);
@ -141,6 +145,15 @@ void Kf_Conf::SetFromConfiguration(const ConfigurationInterface *configuration,
carrier_freq_sd_hz = configuration->property(role + ".carrier_freq_sd_hz", 0.1);
carrier_freq_rate_sd_hz_s = configuration->property(role + ".carrier_freq_rate_sd_hz_s", 1);
//System covariances (narrow) (Q)
narrow_code_phase_sd_chips = configuration->property(role + ".narrow_code_phase_sd_chips", 0.001);
narrow_code_rate_sd_chips_s = configuration->property(role + ".narrow_code_rate_sd_chips_s", 0.001);
narrow_carrier_phase_sd_rad = configuration->property(role + ".narrow_carrier_phase_sd_rad", 0.001);
narrow_carrier_freq_sd_hz = configuration->property(role + ".narrow_carrier_freq_sd_hz", 0.1);
narrow_carrier_freq_rate_sd_hz_s = configuration->property(role + ".narrow_carrier_freq_rate_sd_hz_s", 1);
//initial Kalman covariance matrix (P)
init_code_phase_sd_chips = configuration->property(role + ".init_code_phase_sd_chips", 1);
init_code_rate_sd_chips_s = configuration->property(role + ".init_code_rate_sd_chips_s", 100);

13
src/algorithms/tracking/libs/kf_conf.h
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@ -69,6 +69,10 @@ public:
//states: code_phase_chips, carrier_phase_rads, carrier_freq_hz, carrier_freq_rate_hz_s, code_freq_rate_chips_s
//Measurement covariances (R)
double expected_cn0_dbhz;
double code_disc_sd_chips;
double carrier_disc_sd_rads;
//System covariances (Q)
double code_phase_sd_chips;
double code_rate_sd_chips_s;
@ -76,6 +80,15 @@ public:
double carrier_phase_sd_rad;
double carrier_freq_sd_hz;
double carrier_freq_rate_sd_hz_s;
//System covariances (narrow) (Q)
double narrow_code_phase_sd_chips;
double narrow_code_rate_sd_chips_s;
double narrow_carrier_phase_sd_rad;
double narrow_carrier_freq_sd_hz;
double narrow_carrier_freq_rate_sd_hz_s;
//initial Kalman covariance matrix (P)
double init_code_phase_sd_chips;
double init_code_rate_sd_chips_s;