/*! * \file gps_l1_ca_tcp_connector_tracking_cc.cc * \brief Implementation of a TCP connector block based on Code DLL + carrier PLL * \author David Pubill, 2012. dpubill(at)cttc.es * Javier Arribas, 2011. jarribas(at)cttc.es * * * Code DLL + carrier PLL according to the algorithms described in: * [1] K.Borre, D.M.Akos, N.Bertelsen, P.Rinder, and S.H.Jensen, * A Software-Defined GPS and Galileo Receiver. A Single-Frequency * Approach, Birkhauser, 2007 * * ----------------------------------------------------------------------------- * * GNSS-SDR is a Global Navigation Satellite System software-defined receiver. * This file is part of GNSS-SDR. * * Copyright (C) 2010-2020 (see AUTHORS file for a list of contributors) * SPDX-License-Identifier: GPL-3.0-or-later * * ----------------------------------------------------------------------------- */ #include "gps_l1_ca_tcp_connector_tracking_cc.h" #include "GPS_L1_CA.h" #include "gnss_satellite.h" #include "gnss_sdr_flags.h" #include "gps_sdr_signal_replica.h" #include "lock_detectors.h" #include "tcp_communication.h" #include "tcp_packet_data.h" #include "tracking_discriminators.h" #include #include #include #include #include #include #include #include gps_l1_ca_tcp_connector_tracking_cc_sptr gps_l1_ca_tcp_connector_make_tracking_cc( int64_t fs_in, uint32_t vector_length, bool dump, const std::string &dump_filename, float early_late_space_chips, size_t port_ch0) { return gps_l1_ca_tcp_connector_tracking_cc_sptr(new Gps_L1_Ca_Tcp_Connector_Tracking_cc( fs_in, vector_length, dump, dump_filename, early_late_space_chips, port_ch0)); } void Gps_L1_Ca_Tcp_Connector_Tracking_cc::forecast(int noutput_items, gr_vector_int &ninput_items_required) { if (noutput_items != 0) { ninput_items_required[0] = static_cast(d_vector_length) * 2; // set the required available samples in each call } } Gps_L1_Ca_Tcp_Connector_Tracking_cc::Gps_L1_Ca_Tcp_Connector_Tracking_cc( int64_t fs_in, uint32_t vector_length, bool dump, const std::string &dump_filename, float early_late_space_chips, size_t port_ch0) : gr::block("Gps_L1_Ca_Tcp_Connector_Tracking_cc", gr::io_signature::make(1, 1, sizeof(gr_complex)), gr::io_signature::make(1, 1, sizeof(Gnss_Synchro))) { this->message_port_register_out(pmt::mp("events")); this->message_port_register_in(pmt::mp("telemetry_to_trk")); // initialize internal vars d_dump = dump; d_fs_in = fs_in; d_vector_length = vector_length; d_dump_filename = dump_filename; // -- DLL variables -------------------------------------------------------- d_early_late_spc_chips = early_late_space_chips; // Define early-late offset (in chips) // -- TCP CONNECTOR variables -------------------------------------------------------- d_port_ch0 = port_ch0; d_port = 0; d_listen_connection = true; d_control_id = 0; // Initialization of local code replica // Get space for a vector with the C/A code replica sampled 1x/chip d_ca_code.resize(GPS_L1_CA_CODE_LENGTH_CHIPS); // correlator outputs (scalar) d_n_correlator_taps = 3; // Very-Early, Early, Prompt, Late, Very-Late d_correlator_outs.resize(d_n_correlator_taps); std::fill_n(d_correlator_outs.begin(), d_n_correlator_taps, gr_complex(0.0, 0.0)); // map memory pointers of correlator outputs d_Early = &d_correlator_outs[0]; d_Prompt = &d_correlator_outs[1]; d_Late = &d_correlator_outs[2]; d_local_code_shift_chips = volk_gnsssdr::vector(d_n_correlator_taps); // 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; d_correlation_length_samples = d_vector_length; multicorrelator_cpu.init(2 * d_correlation_length_samples, d_n_correlator_taps); // --- Perform initializations ------------------------------ // define initial code frequency basis of NCO d_code_freq_hz = GPS_L1_CA_CODE_RATE_CPS; // define residual code phase (in chips) d_rem_code_phase_samples = 0.0; // define residual carrier phase d_rem_carr_phase_rad = 0.0; // sample synchronization d_sample_counter = 0ULL; d_sample_counter_seconds = 0; d_acq_sample_stamp = 0ULL; d_enable_tracking = false; d_pull_in = false; d_current_prn_length_samples = static_cast(d_vector_length); // CN0 estimation and lock detector buffers d_cn0_estimation_counter = 0; d_Prompt_buffer = volk_gnsssdr::vector(FLAGS_cn0_samples); d_carrier_lock_test = 1; d_CN0_SNV_dB_Hz = 0; d_carrier_lock_fail_counter = 0; d_carrier_lock_threshold = static_cast(FLAGS_carrier_lock_th); systemName["G"] = std::string("GPS"); systemName["R"] = std::string("GLONASS"); systemName["S"] = std::string("SBAS"); systemName["E"] = std::string("Galileo"); systemName["C"] = std::string("Compass"); d_acquisition_gnss_synchro = nullptr; d_channel = 0; d_next_rem_code_phase_samples = 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_rad = 0.0; d_code_phase_samples = 0; d_next_prn_length_samples = 0; d_code_phase_step_chips = 0.0; } void Gps_L1_Ca_Tcp_Connector_Tracking_cc::start_tracking() { /* * correct the code phase according to the delay between acq and trk */ d_acq_code_phase_samples = static_cast(d_acquisition_gnss_synchro->Acq_delay_samples); d_acq_carrier_doppler_hz = static_cast(d_acquisition_gnss_synchro->Acq_doppler_hz); d_acq_sample_stamp = d_acquisition_gnss_synchro->Acq_samplestamp_samples; int64_t acq_trk_diff_samples; float acq_trk_diff_seconds; acq_trk_diff_samples = static_cast(d_sample_counter) - static_cast(d_acq_sample_stamp); std::cout << "acq_trk_diff_samples=" << acq_trk_diff_samples << '\n'; acq_trk_diff_seconds = static_cast(acq_trk_diff_samples) / static_cast(d_fs_in); // doppler effect // Fd=(C/(C+Vr))*F auto radial_velocity = static_cast((GPS_L1_FREQ_HZ + d_acq_carrier_doppler_hz) / GPS_L1_FREQ_HZ); // new chip and prn sequence periods based on acq Doppler float T_chip_mod_seconds; float T_prn_mod_seconds; float T_prn_mod_samples; d_code_freq_hz = radial_velocity * GPS_L1_CA_CODE_RATE_CPS; d_code_phase_step_chips = static_cast(d_code_freq_hz) / static_cast(d_fs_in); T_chip_mod_seconds = static_cast(1.0 / d_code_freq_hz); T_prn_mod_seconds = static_cast(T_chip_mod_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS); T_prn_mod_samples = T_prn_mod_seconds * static_cast(d_fs_in); d_next_prn_length_samples = std::round(T_prn_mod_samples); float T_prn_true_seconds = GPS_L1_CA_CODE_LENGTH_CHIPS / GPS_L1_CA_CODE_RATE_CPS; float T_prn_true_samples = T_prn_true_seconds * static_cast(d_fs_in); float T_prn_diff_seconds; T_prn_diff_seconds = T_prn_true_seconds - T_prn_mod_seconds; float N_prn_diff; N_prn_diff = acq_trk_diff_seconds / T_prn_true_seconds; float corrected_acq_phase_samples; float delay_correction_samples; corrected_acq_phase_samples = std::fmod((d_acq_code_phase_samples + T_prn_diff_seconds * N_prn_diff * static_cast(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; // 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); multicorrelator_cpu.set_local_code_and_taps(static_cast(GPS_L1_CA_CODE_LENGTH_CHIPS), d_ca_code.data(), d_local_code_shift_chips.data()); std::fill_n(d_correlator_outs.begin(), d_n_correlator_taps, gr_complex(0.0, 0.0)); d_carrier_lock_fail_counter = 0; d_rem_code_phase_samples = 0; d_rem_carr_phase_rad = 0; d_rem_code_phase_samples = 0; d_next_rem_code_phase_samples = 0; d_acc_carrier_phase_rad = 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 of GPS L1 C/A signal started on channel " << d_channel << " for satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << '\n'; LOG(INFO) << "Tracking of GPS L1 C/A signal for satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << " on channel " << d_channel; // enable tracking d_pull_in = true; d_enable_tracking = true; 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_Tcp_Connector_Tracking_cc::~Gps_L1_Ca_Tcp_Connector_Tracking_cc() { if (d_dump_file.is_open()) { try { d_dump_file.close(); } catch (const std::exception &ex) { LOG(WARNING) << "Exception in Tracking block destructor: " << ex.what(); } } try { d_tcp_com.close_tcp_connection(d_port); multicorrelator_cpu.free(); } catch (const std::exception &ex) { LOG(WARNING) << "Exception in Tracking block destructor: " << ex.what(); } } void Gps_L1_Ca_Tcp_Connector_Tracking_cc::set_channel(uint32_t 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(std::to_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(); } catch (const std::ifstream::failure &e) { LOG(WARNING) << "channel " << d_channel << " Exception opening trk dump file " << e.what(); } } } //! Listen for connections on a TCP port if (d_listen_connection == true) { d_port = d_port_ch0 + d_channel; d_listen_connection = d_tcp_com.listen_tcp_connection(d_port, d_port_ch0); } } void Gps_L1_Ca_Tcp_Connector_Tracking_cc::set_gnss_synchro(Gnss_Synchro *p_gnss_synchro) { d_acquisition_gnss_synchro = p_gnss_synchro; } int Gps_L1_Ca_Tcp_Connector_Tracking_cc::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) { // process vars float carr_error = 0.0; float code_error = 0.0; float code_nco = 0.0; bool loss_of_lock = false; Tcp_Packet_Data tcp_data; // GNSS_SYNCHRO OBJECT to interchange data between tracking->telemetry_decoder Gnss_Synchro current_synchro_data = Gnss_Synchro(); // Block input data and block output stream pointers const auto *in = reinterpret_cast(input_items[0]); auto **out = reinterpret_cast(&output_items[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) { int32_t samples_offset; // 28/11/2011 ACQ to TRK transition BUG CORRECTION float acq_trk_shif_correction_samples; int32_t acq_to_trk_delay_samples; acq_to_trk_delay_samples = d_sample_counter - d_acq_sample_stamp; acq_trk_shif_correction_samples = d_next_prn_length_samples - std::fmod(static_cast(acq_to_trk_delay_samples), static_cast(d_next_prn_length_samples)); samples_offset = std::round(d_acq_code_phase_samples + acq_trk_shif_correction_samples); current_synchro_data.Tracking_sample_counter = d_sample_counter + static_cast(samples_offset); current_synchro_data.fs = d_fs_in; *out[0] = current_synchro_data; d_sample_counter_seconds = d_sample_counter_seconds + (static_cast(samples_offset) / static_cast(d_fs_in)); d_sample_counter = d_sample_counter + static_cast(samples_offset); // count for the processed samples d_pull_in = false; consume_each(samples_offset); // shift input to perform alignment with local replica return 1; } // Update the prn length based on code freq (variable) and // sampling frequency (fixed) // variable code PRN sample block size d_current_prn_length_samples = d_next_prn_length_samples; // ################# CARRIER WIPEOFF AND CORRELATORS ############################## // perform carrier wipe-off and compute Early, Prompt and Late correlation multicorrelator_cpu.set_input_output_vectors(d_correlator_outs.data(), in); double carr_phase_step_rad = TWO_PI * d_carrier_doppler_hz / static_cast(d_fs_in); double rem_code_phase_chips = d_rem_code_phase_samples * (d_code_freq_hz / d_fs_in); multicorrelator_cpu.Carrier_wipeoff_multicorrelator_resampler(d_rem_carr_phase_rad, static_cast(carr_phase_step_rad), static_cast(rem_code_phase_chips), static_cast(d_code_phase_step_chips), d_current_prn_length_samples); // Variable used for control d_control_id++; // Send and receive a TCP packet boost::array tx_variables_array = {{d_control_id, (*d_Early).real(), (*d_Early).imag(), (*d_Late).real(), (*d_Late).imag(), (*d_Prompt).real(), (*d_Prompt).imag(), d_acq_carrier_doppler_hz, 1}}; d_tcp_com.send_receive_tcp_packet_gps_l1_ca(tx_variables_array, &tcp_data); // Recover the tracking data code_error = tcp_data.proc_pack_code_error; carr_error = tcp_data.proc_pack_carr_error; // Modify carrier freq based on NCO command d_carrier_doppler_hz = tcp_data.proc_pack_carrier_doppler_hz; // Modify code freq based on NCO command code_nco = static_cast(1.0 / (1.0 / GPS_L1_CA_CODE_RATE_CPS - code_error / GPS_L1_CA_CODE_LENGTH_CHIPS)); d_code_freq_hz = code_nco; // Update the phasestep based on code freq (variable) and // sampling frequency (fixed) d_code_phase_step_chips = d_code_freq_hz / static_cast(d_fs_in); // [chips] // variable code PRN sample block size double T_chip_seconds; double T_prn_seconds; double T_prn_samples; double K_blk_samples; T_chip_seconds = 1.0 / static_cast(d_code_freq_hz); T_prn_seconds = T_chip_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS; T_prn_samples = T_prn_seconds * static_cast(d_fs_in); d_rem_code_phase_samples = d_next_rem_code_phase_samples; K_blk_samples = T_prn_samples + d_rem_code_phase_samples; // -code_error*(double)d_fs_in; // Update the current PRN delay (code phase in samples) double T_prn_true_seconds = GPS_L1_CA_CODE_LENGTH_CHIPS / GPS_L1_CA_CODE_RATE_CPS; double T_prn_true_samples = T_prn_true_seconds * static_cast(d_fs_in); d_code_phase_samples = d_code_phase_samples + T_prn_samples - T_prn_true_samples; if (d_code_phase_samples < 0) { d_code_phase_samples = T_prn_true_samples + d_code_phase_samples; } d_code_phase_samples = fmod(d_code_phase_samples, T_prn_true_samples); d_next_prn_length_samples = round(K_blk_samples); // round to a discrete number of samples d_next_rem_code_phase_samples = K_blk_samples - d_next_prn_length_samples; // rounding error /*! * \todo Improve the lock detection algorithm! */ // ####### CN0 ESTIMATION AND LOCK DETECTORS ###### if (d_cn0_estimation_counter < FLAGS_cn0_samples) { // fill buffer with prompt correlator output values d_Prompt_buffer[d_cn0_estimation_counter] = *d_Prompt; d_cn0_estimation_counter++; } else { d_cn0_estimation_counter = 0; d_CN0_SNV_dB_Hz = cn0_m2m4_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), FLAGS_cn0_samples); // ###### TRACKING UNLOCK NOTIFICATION ##### if (d_carrier_lock_test < d_carrier_lock_threshold or d_CN0_SNV_dB_Hz < FLAGS_cn0_min) { d_carrier_lock_fail_counter++; } else { if (d_carrier_lock_fail_counter > 0) { d_carrier_lock_fail_counter--; } } if (d_carrier_lock_fail_counter > FLAGS_max_lock_fail) { std::cout << "Loss of lock in channel " << d_channel << "!\n"; 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 loss_of_lock = true; } } // ########### Output the tracking data to navigation and PVT ########## current_synchro_data.Prompt_I = static_cast((*d_Prompt).real()); current_synchro_data.Prompt_Q = static_cast((*d_Prompt).imag()); // compute remnant code phase samples AFTER the Tracking timestamp d_rem_code_phase_samples = K_blk_samples - d_current_prn_length_samples; // rounding error < 1 sample current_synchro_data.Tracking_sample_counter = d_sample_counter + static_cast(d_current_prn_length_samples); current_synchro_data.Code_phase_samples = d_rem_code_phase_samples; current_synchro_data.Carrier_phase_rads = static_cast(d_acc_carrier_phase_rad); current_synchro_data.Carrier_Doppler_hz = static_cast(d_carrier_doppler_hz); current_synchro_data.CN0_dB_hz = static_cast(d_CN0_SNV_dB_Hz); current_synchro_data.Flag_valid_symbol_output = !loss_of_lock; current_synchro_data.correlation_length_ms = 1; } else { *d_Early = gr_complex(0.0, 0.0); *d_Prompt = gr_complex(0.0, 0.0); *d_Late = gr_complex(0.0, 0.0); // GNSS_SYNCHRO OBJECT to interchange data between tracking->telemetry_decoder current_synchro_data.Tracking_sample_counter = d_sample_counter + static_cast(d_correlation_length_samples); // When tracking is disabled an array of 1's is sent to maintain the TCP connection boost::array tx_variables_array = {{1, 1, 1, 1, 1, 1, 1, 1, 0}}; d_tcp_com.send_receive_tcp_packet_gps_l1_ca(tx_variables_array, &tcp_data); } // assign the GNU Radio block output data current_synchro_data.System = {'G'}; current_synchro_data.Signal[0] = '1'; current_synchro_data.Signal[1] = 'C'; current_synchro_data.Signal[2] = '\0'; current_synchro_data.fs = 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; float tmp_P; float tmp_L; float tmp_VE = 0.0; float tmp_VL = 0.0; float tmp_float; prompt_I = d_correlator_outs[1].real(); prompt_Q = d_correlator_outs[1].imag(); tmp_E = std::abs(d_correlator_outs[0]); tmp_P = std::abs(d_correlator_outs[1]); tmp_L = std::abs(d_correlator_outs[2]); try { // Dump correlators output d_dump_file.write(reinterpret_cast(&tmp_VE), sizeof(float)); d_dump_file.write(reinterpret_cast(&tmp_E), sizeof(float)); d_dump_file.write(reinterpret_cast(&tmp_P), sizeof(float)); d_dump_file.write(reinterpret_cast(&tmp_L), sizeof(float)); d_dump_file.write(reinterpret_cast(&tmp_VL), sizeof(float)); // PROMPT I and Q (to analyze navigation symbols) d_dump_file.write(reinterpret_cast(&prompt_I), sizeof(float)); d_dump_file.write(reinterpret_cast(&prompt_Q), sizeof(float)); // PRN start sample stamp d_dump_file.write(reinterpret_cast(&d_sample_counter), sizeof(uint64_t)); // accumulated carrier phase tmp_float = static_cast(d_acc_carrier_phase_rad); d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // carrier and code frequency tmp_float = static_cast(d_carrier_doppler_hz); d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = static_cast(d_code_freq_hz); d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // PLL commands tmp_float = 0.0; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = carr_error; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // DLL commands tmp_float = 0.0; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = code_error; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // CN0 and carrier lock test tmp_float = static_cast(d_CN0_SNV_dB_Hz); d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = static_cast(d_carrier_lock_test); d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // AUX vars (for debug purposes) tmp_float = 0.0; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); auto tmp_double = static_cast(d_sample_counter + d_correlation_length_samples); d_dump_file.write(reinterpret_cast(&tmp_double), sizeof(double)); // PRN uint32_t prn_ = d_acquisition_gnss_synchro->PRN; d_dump_file.write(reinterpret_cast(&prn_), sizeof(uint32_t)); } catch (const std::ifstream::failure &e) { LOG(WARNING) << "Exception writing trk dump file " << e.what(); } } consume_each(d_current_prn_length_samples); // this is necessary in gr::block derivates d_sample_counter_seconds = d_sample_counter_seconds + (static_cast(d_current_prn_length_samples) / static_cast(d_fs_in)); d_sample_counter += d_current_prn_length_samples; // count for the processed samples if (d_enable_tracking || loss_of_lock) { return 1; } return 0; }