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gnss-sdr/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_c_aid_tra...

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/*!
* \file gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc.cc
* \brief Implementation of a code DLL + carrier PLL tracking block
* \author Javier Arribas, 2015. jarribas(at)cttc.es
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2015 (see AUTHORS file for a list of contributors)
*
* GNSS-SDR is a software defined Global Navigation
* Satellite Systems receiver
*
* This file is part of GNSS-SDR.
*
* GNSS-SDR is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GNSS-SDR is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc.h"
#include <cmath>
#include <iostream>
#include <memory>
#include <sstream>
#include <boost/bind.hpp>
#include <boost/lexical_cast.hpp>
#include <gnuradio/io_signature.h>
#include <pmt/pmt.h>
#include <volk_gnsssdr/volk_gnsssdr.h>
#include <glog/logging.h>
#include "gnss_synchro.h"
#include "gps_sdr_signal_processing.h"
#include "tracking_discriminators.h"
#include "lock_detectors.h"
#include "GPS_L1_CA.h"
#include "control_message_factory.h"
/*!
* \todo Include in definition header file
*/
#define CN0_ESTIMATION_SAMPLES 20
#define MINIMUM_VALID_CN0 25
#define MAXIMUM_LOCK_FAIL_COUNTER 50
#define CARRIER_LOCK_THRESHOLD 0.85
using google::LogMessage;
gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc_sptr
gps_l1_ca_dll_pll_c_aid_make_tracking_fpga_sc(
long if_freq,
long fs_in,
unsigned int vector_length,
bool dump,
std::string dump_filename,
float pll_bw_hz,
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_fpga_sc_sptr(new gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc(if_freq,
fs_in, vector_length, dump, dump_filename, pll_bw_hz, dll_bw_hz, pll_bw_narrow_hz, dll_bw_narrow_hz, extend_correlation_ms, early_late_space_chips));
}
void gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::forecast (int noutput_items,
gr_vector_int &ninput_items_required)
{
if (noutput_items != 0)
{
ninput_items_required[0] = static_cast<int>(d_vector_length) * 2; //set the required available samples in each call
}
}
void gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::msg_handler_preamble_index(pmt::pmt_t msg)
{
//pmt::print(msg);
DLOG(INFO) << "Extended correlation enabled for Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN);
if (d_enable_extended_integration == false) //avoid re-setting preamble indicator
{
d_preamble_timestamp_s = pmt::to_double(msg);
d_enable_extended_integration = true;
d_preamble_synchronized = false;
}
}
gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc(
long if_freq,
long fs_in,
unsigned int vector_length,
bool dump,
std::string dump_filename,
float pll_bw_hz,
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_fpga_sc", gr::io_signature::make(1, 1, sizeof(lv_16sc_t)),
gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)))
{
// Telemetry bit synchronization message port input
this->message_port_register_in(pmt::mp("preamble_timestamp_s"));
this->set_msg_handler(pmt::mp("preamble_timestamp_s"),
boost::bind(&gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::msg_handler_preamble_index, this, _1));
this->message_port_register_out(pmt::mp("events"));
// initialize internal vars
d_dump = dump;
d_if_freq = if_freq;
d_fs_in = fs_in;
d_vector_length = vector_length;
d_dump_filename = dump_filename;
d_correlation_length_samples = static_cast<int>(d_vector_length);
// Initialize tracking ==========================================
d_pll_bw_hz = pll_bw_hz;
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_code_loop_filter.set_DLL_BW(d_dll_bw_hz);
d_carrier_loop_filter.set_params(10.0, d_pll_bw_hz, 2);
d_extend_correlation_ms = extend_correlation_ms;
// --- DLL variables --------------------------------------------------------
d_early_late_spc_chips = early_late_space_chips; // Define early-late offset (in chips)
// Initialization of local code replica
// Get space for a vector with the C/A code replica sampled 1x/chip
d_ca_code = static_cast<gr_complex*>(volk_gnsssdr_malloc(static_cast<int>(GPS_L1_CA_CODE_LENGTH_CHIPS) * sizeof(gr_complex), volk_gnsssdr_get_alignment()));
d_ca_code_16sc = static_cast<lv_16sc_t*>(volk_gnsssdr_malloc(static_cast<int>(GPS_L1_CA_CODE_LENGTH_CHIPS) * sizeof(lv_16sc_t), volk_gnsssdr_get_alignment()));
// correlator outputs (scalar)
d_n_correlator_taps = 3; // Early, Prompt, and Late
d_correlator_outs_16sc = static_cast<lv_16sc_t*>(volk_gnsssdr_malloc(d_n_correlator_taps*sizeof(lv_16sc_t), volk_gnsssdr_get_alignment()));
for (int n = 0; n < d_n_correlator_taps; n++)
{
d_correlator_outs_16sc[n] = lv_cmake(0,0);
}
d_local_code_shift_chips = static_cast<float*>(volk_gnsssdr_malloc(d_n_correlator_taps*sizeof(float), volk_gnsssdr_get_alignment()));
// Set TAPs delay values [chips]
d_local_code_shift_chips[0] = - d_early_late_spc_chips;
d_local_code_shift_chips[1] = 0.0;
d_local_code_shift_chips[2] = d_early_late_spc_chips;
multicorrelator_fpga_8sc.init(2 * d_correlation_length_samples, d_n_correlator_taps);
//--- Perform initializations ------------------------------
// define initial code frequency basis of NCO
d_code_freq_chips = GPS_L1_CA_CODE_RATE_HZ;
// define residual code phase (in chips)
d_rem_code_phase_samples = 0.0;
// define residual carrier phase
d_rem_carrier_phase_rad = 0.0;
// sample synchronization
d_sample_counter = 0; //(from trk to tlm)
d_acq_sample_stamp = 0;
d_enable_tracking = false;
d_pull_in = false;
// CN0 estimation and lock detector buffers
d_cn0_estimation_counter = 0;
d_Prompt_buffer = new gr_complex[CN0_ESTIMATION_SAMPLES];
d_carrier_lock_test = 1;
d_CN0_SNV_dB_Hz = 0;
d_carrier_lock_fail_counter = 0;
d_carrier_lock_threshold = CARRIER_LOCK_THRESHOLD;
systemName["G"] = std::string("GPS");
systemName["S"] = std::string("SBAS");
set_relative_rate(1.0 / static_cast<double>(d_vector_length));
d_acquisition_gnss_synchro = 0;
d_channel = 0;
d_acq_code_phase_samples = 0.0;
d_acq_carrier_doppler_hz = 0.0;
d_carrier_doppler_hz = 0.0;
d_acc_carrier_phase_cycles = 0.0;
d_code_phase_samples = 0.0;
d_enable_extended_integration = false;
d_preamble_synchronized = false;
d_rem_code_phase_integer_samples = 0;
d_code_error_chips_Ti = 0.0;
d_pll_to_dll_assist_secs_Ti = 0.0;
d_rem_code_phase_chips = 0.0;
d_code_phase_step_chips = 0.0;
d_carrier_phase_step_rad = 0.0;
d_code_error_filt_chips_s = 0.0;
d_code_error_filt_chips_Ti = 0.0;
d_preamble_timestamp_s = 0.0;
d_carr_phase_error_secs_Ti = 0.0;
//set_min_output_buffer((long int)300);
}
void gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::start_tracking()
{
/*
* correct the code phase according to the delay between acq and trk
*/
d_acq_code_phase_samples = d_acquisition_gnss_synchro->Acq_delay_samples;
d_acq_carrier_doppler_hz = d_acquisition_gnss_synchro->Acq_doppler_hz;
d_acq_sample_stamp = d_acquisition_gnss_synchro->Acq_samplestamp_samples;
long int acq_trk_diff_samples;
double acq_trk_diff_seconds;
acq_trk_diff_samples = static_cast<long int>(d_sample_counter) - static_cast<long int>(d_acq_sample_stamp);//-d_vector_length;
DLOG(INFO) << "Number of samples between Acquisition and Tracking =" << acq_trk_diff_samples;
acq_trk_diff_seconds = static_cast<double>(acq_trk_diff_samples) / static_cast<double>(d_fs_in);
// Doppler effect
// Fd=(C/(C+Vr))*F
double radial_velocity = (GPS_L1_FREQ_HZ + d_acq_carrier_doppler_hz) / GPS_L1_FREQ_HZ;
// new chip and prn sequence periods based on acq Doppler
double T_chip_mod_seconds;
double T_prn_mod_seconds;
double T_prn_mod_samples;
d_code_freq_chips = radial_velocity * GPS_L1_CA_CODE_RATE_HZ;
d_code_phase_step_chips = static_cast<double>(d_code_freq_chips) / static_cast<double>(d_fs_in);
T_chip_mod_seconds = 1.0 / d_code_freq_chips;
T_prn_mod_seconds = T_chip_mod_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS;
T_prn_mod_samples = T_prn_mod_seconds * static_cast<double>(d_fs_in);
d_correlation_length_samples = round(T_prn_mod_samples);
double T_prn_true_seconds = GPS_L1_CA_CODE_LENGTH_CHIPS / GPS_L1_CA_CODE_RATE_HZ;
double T_prn_true_samples = T_prn_true_seconds * static_cast<double>(d_fs_in);
double T_prn_diff_seconds = T_prn_true_seconds - T_prn_mod_seconds;
double N_prn_diff = acq_trk_diff_seconds / T_prn_true_seconds;
double corrected_acq_phase_samples, delay_correction_samples;
corrected_acq_phase_samples = fmod((d_acq_code_phase_samples + T_prn_diff_seconds * N_prn_diff * static_cast<double>(d_fs_in)), T_prn_true_samples);
if (corrected_acq_phase_samples < 0)
{
corrected_acq_phase_samples = T_prn_mod_samples + corrected_acq_phase_samples;
}
delay_correction_samples = d_acq_code_phase_samples - corrected_acq_phase_samples;
d_acq_code_phase_samples = corrected_acq_phase_samples;
d_carrier_doppler_hz = d_acq_carrier_doppler_hz;
d_carrier_phase_step_rad = GPS_TWO_PI * d_carrier_doppler_hz / static_cast<double>(d_fs_in);
// DLL/PLL filter initialization
d_carrier_loop_filter.initialize(d_acq_carrier_doppler_hz); // The carrier loop filter implements the Doppler accumulator
d_code_loop_filter.initialize(); // initialize the code filter
// generate local reference ALWAYS starting at chip 1 (1 sample per chip)
gps_l1_ca_code_gen_complex(d_ca_code, d_acquisition_gnss_synchro->PRN, 0);
volk_gnsssdr_32fc_convert_16ic(d_ca_code_16sc, d_ca_code, static_cast<int>(GPS_L1_CA_CODE_LENGTH_CHIPS));
multicorrelator_fpga_8sc.set_local_code_and_taps(static_cast<int>(GPS_L1_CA_CODE_LENGTH_CHIPS), d_ca_code_16sc, d_local_code_shift_chips);
for (int n = 0; n < d_n_correlator_taps; n++)
{
d_correlator_outs_16sc[n] = lv_16sc_t(0,0);
}
d_carrier_lock_fail_counter = 0;
d_rem_code_phase_samples = 0.0;
d_rem_carrier_phase_rad = 0.0;
d_rem_code_phase_chips = 0.0;
d_acc_carrier_phase_cycles = 0.0;
d_pll_to_dll_assist_secs_Ti = 0.0;
d_code_phase_samples = d_acq_code_phase_samples;
std::string sys_ = &d_acquisition_gnss_synchro->System;
sys = sys_.substr(0,1);
// DEBUG OUTPUT
std::cout << "Tracking start on channel " << d_channel << " for satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << std::endl;
LOG(INFO) << "Starting tracking of satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << " on channel " << d_channel;
// enable tracking
d_pull_in = true;
d_enable_tracking = true;
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
<< " PULL-IN Code Phase [samples]=" << d_acq_code_phase_samples;
}
gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::~gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc()
{
d_dump_file.close();
volk_gnsssdr_free(d_local_code_shift_chips);
volk_gnsssdr_free(d_ca_code);
volk_gnsssdr_free(d_ca_code_16sc);
volk_gnsssdr_free(d_correlator_outs_16sc);
delete[] d_Prompt_buffer;
multicorrelator_fpga_8sc.free();
}
int gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::general_work (int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
{
// Block input data and block output stream pointers
const lv_16sc_t* in = (lv_16sc_t*) input_items[0]; //PRN start block alignment
Gnss_Synchro **out = (Gnss_Synchro **) &output_items[0];
// GNSS_SYNCHRO OBJECT to interchange data between tracking->telemetry_decoder
Gnss_Synchro current_synchro_data = Gnss_Synchro();
// process vars
double code_error_filt_secs_Ti = 0.0;
double CURRENT_INTEGRATION_TIME_S = 0.0;
double CORRECTED_INTEGRATION_TIME_S = 0.0;
if (d_enable_tracking == true)
{
// Fill the acquisition data
current_synchro_data = *d_acquisition_gnss_synchro;
// Receiver signal alignment
if (d_pull_in == true)
{
int samples_offset;
double acq_trk_shif_correction_samples;
int acq_to_trk_delay_samples;
acq_to_trk_delay_samples = d_sample_counter - d_acq_sample_stamp;
acq_trk_shif_correction_samples = d_correlation_length_samples - fmod(static_cast<double>(acq_to_trk_delay_samples), static_cast<double>(d_correlation_length_samples));
samples_offset = round(d_acq_code_phase_samples + acq_trk_shif_correction_samples);
current_synchro_data.Tracking_timestamp_secs = (static_cast<double>(d_sample_counter) + static_cast<double>(d_rem_code_phase_samples)) / static_cast<double>(d_fs_in);
d_sample_counter += samples_offset; // count for the processed samples
d_pull_in = false;
d_acc_carrier_phase_cycles -= d_carrier_phase_step_rad * samples_offset / GPS_TWO_PI;
current_synchro_data.Carrier_phase_rads = d_acc_carrier_phase_cycles * GPS_TWO_PI;
current_synchro_data.Carrier_Doppler_hz = d_carrier_doppler_hz;
*out[0] = current_synchro_data;
consume_each(samples_offset); // shift input to perform alignment with local replica
return 1;
}
// ################# CARRIER WIPEOFF AND CORRELATORS ##############################
// perform carrier wipe-off and compute Early, Prompt and Late correlation
multicorrelator_fpga_8sc.set_input_output_vectors(d_correlator_outs_16sc, in);
multicorrelator_fpga_8sc.Carrier_wipeoff_multicorrelator_resampler(d_rem_carrier_phase_rad,
d_carrier_phase_step_rad,
d_rem_code_phase_chips,
d_code_phase_step_chips,
d_correlation_length_samples);
// ####### coherent intergration extension
// keep the last symbols
d_E_history.push_back(d_correlator_outs_16sc[0]); // save early output
d_P_history.push_back(d_correlator_outs_16sc[1]); // save prompt output
d_L_history.push_back(d_correlator_outs_16sc[2]); // save late output
if (static_cast<int>(d_P_history.size()) > d_extend_correlation_ms)
{
d_E_history.pop_front();
d_P_history.pop_front();
d_L_history.pop_front();
}
bool enable_dll_pll;
if (d_enable_extended_integration == true)
{
long int symbol_diff = round(1000.0 * ((static_cast<double>(d_sample_counter) + d_rem_code_phase_samples) / static_cast<double>(d_fs_in) - d_preamble_timestamp_s));
if (symbol_diff > 0 and symbol_diff % d_extend_correlation_ms == 0)
{
// compute coherent integration and enable tracking loop
// perform coherent integration using correlator output history
// std::cout<<"##### RESET COHERENT INTEGRATION ####"<<std::endl;
d_correlator_outs_16sc[0] = lv_cmake(0,0);
d_correlator_outs_16sc[1] = lv_cmake(0,0);
d_correlator_outs_16sc[2] = lv_cmake(0,0);
for (int n = 0; n < d_extend_correlation_ms; n++)
{
d_correlator_outs_16sc[0] += d_E_history.at(n);
d_correlator_outs_16sc[1] += d_P_history.at(n);
d_correlator_outs_16sc[2] += d_L_history.at(n);
}
if (d_preamble_synchronized == false)
{
d_code_loop_filter.set_DLL_BW(d_dll_bw_narrow_hz);
d_carrier_loop_filter.set_params(10.0, d_pll_bw_narrow_hz,2);
d_preamble_synchronized = true;
std::cout << "Enabled " << d_extend_correlation_ms << " [ms] extended correlator for CH "<< d_channel << " : Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN)
<< " pll_bw = " << d_pll_bw_hz << " [Hz], pll_narrow_bw = " << d_pll_bw_narrow_hz << " [Hz]" << std::endl
<< " dll_bw = " << d_dll_bw_hz << " [Hz], dll_narrow_bw = " << d_dll_bw_narrow_hz << " [Hz]" << std::endl;
}
// UPDATE INTEGRATION TIME
CURRENT_INTEGRATION_TIME_S = static_cast<double>(d_extend_correlation_ms) * GPS_L1_CA_CODE_PERIOD;
enable_dll_pll = true;
}
else
{
if(d_preamble_synchronized == true)
{
// continue extended coherent correlation
// Compute the next buffer length based on the period of the PRN sequence and the code phase error estimation
double T_chip_seconds = 1.0 / d_code_freq_chips;
double T_prn_seconds = T_chip_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS;
double T_prn_samples = T_prn_seconds * static_cast<double>(d_fs_in);
int K_prn_samples = round(T_prn_samples);
double K_T_prn_error_samples = K_prn_samples - T_prn_samples;
d_rem_code_phase_samples = d_rem_code_phase_samples - K_T_prn_error_samples;
d_rem_code_phase_integer_samples = round(d_rem_code_phase_samples); // round to a discrete number of samples
d_correlation_length_samples = K_prn_samples + d_rem_code_phase_integer_samples;
d_rem_code_phase_samples = d_rem_code_phase_samples - d_rem_code_phase_integer_samples;
// code phase step (Code resampler phase increment per sample) [chips/sample]
d_code_phase_step_chips = d_code_freq_chips / static_cast<double>(d_fs_in);
// remnant code phase [chips]
d_rem_code_phase_chips = d_rem_code_phase_samples * (d_code_freq_chips / static_cast<double>(d_fs_in));
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);
// UPDATE ACCUMULATED CARRIER PHASE
CORRECTED_INTEGRATION_TIME_S = (static_cast<double>(d_correlation_length_samples) / static_cast<double>(d_fs_in));
d_acc_carrier_phase_cycles -= d_carrier_phase_step_rad * d_correlation_length_samples / GPS_TWO_PI;
// disable tracking loop and inform telemetry decoder
enable_dll_pll = false;
}
else
{
// perform basic (1ms) correlation
// UPDATE INTEGRATION TIME
CURRENT_INTEGRATION_TIME_S = static_cast<double>(d_correlation_length_samples) / static_cast<double>(d_fs_in);
enable_dll_pll = true;
}
}
}
else
{
// UPDATE INTEGRATION TIME
CURRENT_INTEGRATION_TIME_S = static_cast<double>(d_correlation_length_samples) / static_cast<double>(d_fs_in);
enable_dll_pll = true;
}
if (enable_dll_pll == true)
{
// ################## PLL ##########################################################
// Update PLL discriminator [rads/Ti -> Secs/Ti]
d_carr_phase_error_secs_Ti = pll_cloop_two_quadrant_atan(std::complex<float>(d_correlator_outs_16sc[1].real(),d_correlator_outs_16sc[1].imag())) / GPS_TWO_PI; //prompt output
// Carrier discriminator filter
// NOTICE: The carrier loop filter includes the Carrier Doppler accumulator, as described in Kaplan
// Input [s/Ti] -> output [Hz]
d_carrier_doppler_hz = d_carrier_loop_filter.get_carrier_error(0.0, d_carr_phase_error_secs_Ti, CURRENT_INTEGRATION_TIME_S);
// PLL to DLL assistance [Secs/Ti]
d_pll_to_dll_assist_secs_Ti = (d_carrier_doppler_hz * CURRENT_INTEGRATION_TIME_S) / GPS_L1_FREQ_HZ;
// code Doppler frequency update
d_code_freq_chips = GPS_L1_CA_CODE_RATE_HZ + ((d_carrier_doppler_hz * GPS_L1_CA_CODE_RATE_HZ) / GPS_L1_FREQ_HZ);
// ################## DLL ##########################################################
// DLL discriminator
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(std::complex<float>(d_correlator_outs_16sc[0].real(),d_correlator_outs_16sc[0].imag()), std::complex<float>(d_correlator_outs_16sc[2].real(),d_correlator_outs_16sc[2].imag())); // [chips/Ti] //early and late
// Code discriminator filter
d_code_error_filt_chips_s = d_code_loop_filter.get_code_nco(d_code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
d_code_error_filt_chips_Ti = d_code_error_filt_chips_s * CURRENT_INTEGRATION_TIME_S;
code_error_filt_secs_Ti = d_code_error_filt_chips_Ti / d_code_freq_chips; // [s/Ti]
// ################## CARRIER AND CODE NCO BUFFER ALIGNEMENT #######################
// 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
double T_chip_seconds = 1.0 / d_code_freq_chips;
double T_prn_seconds = T_chip_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS;
double T_prn_samples = T_prn_seconds * static_cast<double>(d_fs_in);
double K_prn_samples = round(T_prn_samples);
double K_T_prn_error_samples = K_prn_samples - T_prn_samples;
d_rem_code_phase_samples = d_rem_code_phase_samples - K_T_prn_error_samples + code_error_filt_secs_Ti * static_cast<double>(d_fs_in); //(code_error_filt_secs_Ti + d_pll_to_dll_assist_secs_Ti) * static_cast<double>(d_fs_in);
d_rem_code_phase_integer_samples = round(d_rem_code_phase_samples); // round to a discrete number of samples
d_correlation_length_samples = K_prn_samples + d_rem_code_phase_integer_samples;
d_rem_code_phase_samples = d_rem_code_phase_samples - d_rem_code_phase_integer_samples;
//################### PLL COMMANDS #################################################
//carrier phase step (NCO phase increment per sample) [rads/sample]
d_carrier_phase_step_rad = GPS_TWO_PI * d_carrier_doppler_hz / static_cast<double>(d_fs_in);
d_acc_carrier_phase_cycles -= d_carrier_phase_step_rad * d_correlation_length_samples / GPS_TWO_PI;
// UPDATE ACCUMULATED CARRIER PHASE
CORRECTED_INTEGRATION_TIME_S = (static_cast<double>(d_correlation_length_samples) / static_cast<double>(d_fs_in));
//remnant carrier phase [rad]
d_rem_carrier_phase_rad = fmod(d_rem_carrier_phase_rad + GPS_TWO_PI * d_carrier_doppler_hz * CORRECTED_INTEGRATION_TIME_S, GPS_TWO_PI);
//################### DLL COMMANDS #################################################
//code phase step (Code resampler phase increment per sample) [chips/sample]
d_code_phase_step_chips = d_code_freq_chips / static_cast<double>(d_fs_in);
//remnant code phase [chips]
d_rem_code_phase_chips = d_rem_code_phase_samples * (d_code_freq_chips / static_cast<double>(d_fs_in));
// ####### CN0 ESTIMATION AND LOCK DETECTORS #######################################
if (d_cn0_estimation_counter < CN0_ESTIMATION_SAMPLES)
{
// fill buffer with prompt correlator output values
d_Prompt_buffer[d_cn0_estimation_counter] = lv_cmake(static_cast<float>(d_correlator_outs_16sc[1].real()), static_cast<float>(d_correlator_outs_16sc[1].imag()) ); // prompt
d_cn0_estimation_counter++;
}
else
{
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
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)
{
d_carrier_lock_fail_counter++;
}
else
{
if (d_carrier_lock_fail_counter > 0) d_carrier_lock_fail_counter--;
}
if (d_carrier_lock_fail_counter > MAXIMUM_LOCK_FAIL_COUNTER)
{
std::cout << "Loss of lock in channel " << d_channel << "!" << std::endl;
LOG(INFO) << "Loss of lock in channel " << d_channel << "!";
this->message_port_pub(pmt::mp("events"), pmt::from_long(3));//3 -> loss of lock
d_carrier_lock_fail_counter = 0;
d_enable_tracking = false; // TODO: check if disabling tracking is consistent with the channel state machine
}
}
// ########### Output the tracking data to navigation and PVT ##########
current_synchro_data.Prompt_I = static_cast<double>((d_correlator_outs_16sc[1]).real());
current_synchro_data.Prompt_Q = static_cast<double>((d_correlator_outs_16sc[1]).imag());
// Tracking_timestamp_secs is aligned with the CURRENT PRN start sample (Hybridization OK!)
current_synchro_data.Tracking_timestamp_secs = (static_cast<double>(d_sample_counter) + d_correlation_length_samples + d_rem_code_phase_samples) / static_cast<double>(d_fs_in);
current_synchro_data.Rem_code_phase_secs = d_rem_code_phase_samples / static_cast<double>(d_fs_in);
current_synchro_data.Carrier_phase_rads = GPS_TWO_PI * d_acc_carrier_phase_cycles;
current_synchro_data.Carrier_Doppler_hz = d_carrier_doppler_hz;
current_synchro_data.CN0_dB_hz = d_CN0_SNV_dB_Hz;
current_synchro_data.Flag_valid_symbol_output = true;
if (d_preamble_synchronized == true)
{
current_synchro_data.correlation_length_ms = d_extend_correlation_ms;
}
else
{
current_synchro_data.correlation_length_ms = 1;
}
}
else
{
current_synchro_data.Prompt_I = static_cast<double>((d_correlator_outs_16sc[1]).real());
current_synchro_data.Prompt_Q = static_cast<double>((d_correlator_outs_16sc[1]).imag());
// Tracking_timestamp_secs is aligned with the CURRENT PRN start sample (Hybridization OK!)
current_synchro_data.Tracking_timestamp_secs = (static_cast<double>(d_sample_counter) + d_correlation_length_samples + d_rem_code_phase_samples) / static_cast<double>(d_fs_in);
current_synchro_data.Rem_code_phase_secs = d_rem_code_phase_samples / static_cast<double>(d_fs_in);
current_synchro_data.Carrier_phase_rads = GPS_TWO_PI * d_acc_carrier_phase_cycles;
current_synchro_data.Carrier_Doppler_hz = d_carrier_doppler_hz;// todo: project the carrier doppler
current_synchro_data.CN0_dB_hz = d_CN0_SNV_dB_Hz;
}
}
else
{
for (int n = 0; n < d_n_correlator_taps; n++)
{
d_correlator_outs_16sc[n] = lv_cmake(0,0);
}
current_synchro_data.System = {'G'};
current_synchro_data.Tracking_timestamp_secs = (static_cast<double>(d_sample_counter) + d_correlation_length_samples + static_cast<double>(d_rem_code_phase_samples)) / static_cast<double>(d_fs_in);
current_synchro_data.Rem_code_phase_secs = d_rem_code_phase_samples / static_cast<double>(d_fs_in);
}
*out[0] = current_synchro_data;
if(d_dump)
{
// MULTIPLEXED FILE RECORDING - Record results to file
float prompt_I;
float prompt_Q;
float tmp_E, tmp_P, tmp_L;
double tmp_double;
prompt_I = d_correlator_outs_16sc[1].real();
prompt_Q = d_correlator_outs_16sc[1].imag();
tmp_E = std::abs<float>(std::complex<float>(d_correlator_outs_16sc[0].real(),d_correlator_outs_16sc[0].imag()));
tmp_P = std::abs<float>(std::complex<float>(d_correlator_outs_16sc[1].real(),d_correlator_outs_16sc[1].imag()));
tmp_L = std::abs<float>(std::complex<float>(d_correlator_outs_16sc[2].real(),d_correlator_outs_16sc[2].imag()));
try
{
// EPR
d_dump_file.write(reinterpret_cast<char*>(&tmp_E), sizeof(float));
d_dump_file.write(reinterpret_cast<char*>(&tmp_P), sizeof(float));
d_dump_file.write(reinterpret_cast<char*>(&tmp_L), sizeof(float));
// PROMPT I and Q (to analyze navigation symbols)
d_dump_file.write(reinterpret_cast<char*>(&prompt_I), sizeof(float));
d_dump_file.write(reinterpret_cast<char*>(&prompt_Q), sizeof(float));
// PRN start sample stamp
//tmp_float=(float)d_sample_counter;
d_dump_file.write(reinterpret_cast<char*>(&d_sample_counter), sizeof(unsigned long int));
// accumulated carrier phase
d_dump_file.write(reinterpret_cast<char*>(&d_acc_carrier_phase_cycles), sizeof(double));
// carrier and code frequency
d_dump_file.write(reinterpret_cast<char*>(&d_carrier_doppler_hz), sizeof(double));
d_dump_file.write(reinterpret_cast<char*>(&d_code_freq_chips), sizeof(double));
//PLL commands
d_dump_file.write(reinterpret_cast<char*>(&d_carr_phase_error_secs_Ti), sizeof(double));
d_dump_file.write(reinterpret_cast<char*>(&d_carrier_doppler_hz), sizeof(double));
//DLL commands
d_dump_file.write(reinterpret_cast<char*>(&d_code_error_chips_Ti), sizeof(double));
d_dump_file.write(reinterpret_cast<char*>(&d_code_error_filt_chips_Ti), sizeof(double));
// CN0 and carrier lock test
d_dump_file.write(reinterpret_cast<char*>(&d_CN0_SNV_dB_Hz), sizeof(double));
d_dump_file.write(reinterpret_cast<char*>(&d_carrier_lock_test), sizeof(double));
// AUX vars (for debug purposes)
tmp_double = d_code_error_chips_Ti * CURRENT_INTEGRATION_TIME_S;
d_dump_file.write(reinterpret_cast<char*>(&tmp_double), sizeof(double));
tmp_double = static_cast<double>(d_sample_counter + d_correlation_length_samples);
d_dump_file.write(reinterpret_cast<char*>(&tmp_double), sizeof(double));
}
catch (const std::ifstream::failure* e)
{
LOG(WARNING) << "Exception writing trk dump file " << e->what();
}
}
consume_each(d_correlation_length_samples); // this is necessary in gr::block derivates
d_sample_counter += d_correlation_length_samples; //count for the processed samples
return 1; //output tracking result ALWAYS even in the case of d_enable_tracking==false
}
void gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::set_channel(unsigned int channel)
{
d_channel = channel;
LOG(INFO) << "Tracking Channel set to " << d_channel;
// ############# ENABLE DATA FILE LOG #################
if (d_dump == true)
{
if (d_dump_file.is_open() == false)
{
try
{
d_dump_filename.append(boost::lexical_cast<std::string>(d_channel));
d_dump_filename.append(".dat");
d_dump_file.exceptions (std::ifstream::failbit | std::ifstream::badbit);
d_dump_file.open(d_dump_filename.c_str(), std::ios::out | std::ios::binary);
LOG(INFO) << "Tracking dump enabled on channel " << d_channel << " Log file: " << d_dump_filename.c_str() << std::endl;
}
catch (const std::ifstream::failure* e)
{
LOG(WARNING) << "channel " << d_channel << " Exception opening trk dump file " << e->what() << std::endl;
}
}
}
}
void gps_l1_ca_dll_pll_c_aid_tracking_fpga_sc::set_gnss_synchro(Gnss_Synchro* p_gnss_synchro)
{
d_acquisition_gnss_synchro = p_gnss_synchro;
}
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