/*! * \file galileo_e1_dll_pll_veml_tracking_cc.cc * \brief Implementation of a code DLL + carrier PLL VEML (Very Early * Minus Late) tracking block for Galileo E1 signals * \author Luis Esteve, 2012. luis(at)epsilon-formacion.com * * 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 * * ------------------------------------------------------------------------- * * 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 . * * ------------------------------------------------------------------------- */ #include "galileo_e1_dll_pll_veml_tracking_cc.h" #include #include #include #include #include #include #include #include #include "galileo_e1_signal_processing.h" #include "tracking_discriminators.h" #include "lock_detectors.h" #include "Galileo_E1.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; galileo_e1_dll_pll_veml_tracking_cc_sptr galileo_e1_dll_pll_veml_make_tracking_cc( long if_freq, long fs_in, unsigned int vector_length, boost::shared_ptr queue, bool dump, std::string dump_filename, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips, float very_early_late_space_chips) { return galileo_e1_dll_pll_veml_tracking_cc_sptr(new galileo_e1_dll_pll_veml_tracking_cc(if_freq, fs_in, vector_length, queue, dump, dump_filename, pll_bw_hz, dll_bw_hz, early_late_space_chips, very_early_late_space_chips)); } void galileo_e1_dll_pll_veml_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 } } galileo_e1_dll_pll_veml_tracking_cc::galileo_e1_dll_pll_veml_tracking_cc( long if_freq, long fs_in, unsigned int vector_length, boost::shared_ptr queue, bool dump, std::string dump_filename, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips, float very_early_late_space_chips): gr::block("galileo_e1_dll_pll_veml_tracking_cc", gr::io_signature::make(1, 1, sizeof(gr_complex)), 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_relative_rate(1.0 / vector_length); this->message_port_register_out(pmt::mp("events")); // initialize internal vars d_queue = queue; d_dump = dump; d_if_freq = if_freq; d_fs_in = fs_in; d_vector_length = vector_length; d_dump_filename = dump_filename; d_code_loop_filter = Tracking_2nd_DLL_filter(Galileo_E1_CODE_PERIOD); d_carrier_loop_filter = Tracking_2nd_PLL_filter(Galileo_E1_CODE_PERIOD); // Initialize tracking ========================================== // Set bandwidth of code and carrier loop filters d_code_loop_filter.set_DLL_BW(dll_bw_hz); d_carrier_loop_filter.set_PLL_BW(pll_bw_hz); // Correlator spacing d_early_late_spc_chips = early_late_space_chips; // Define early-late offset (in chips) d_very_early_late_spc_chips = very_early_late_space_chips; // Define very-early-late offset (in chips) // Initialization of local code replica // Get space for a vector with the sinboc(1,1) replica sampled 2x/chip d_ca_code = static_cast(volk_malloc((2 * Galileo_E1_B_CODE_LENGTH_CHIPS) * sizeof(gr_complex), volk_get_alignment())); // correlator outputs (scalar) d_n_correlator_taps = 5; // Very-Early, Early, Prompt, Late, Very-Late d_correlator_outs = static_cast(volk_malloc(d_n_correlator_taps * sizeof(gr_complex), volk_get_alignment())); for (int n = 0; n < d_n_correlator_taps; n++) { d_correlator_outs[n] = gr_complex(0,0); } // map memory pointers of correlator outputs d_Very_Early = &d_correlator_outs[0]; d_Early = &d_correlator_outs[1]; d_Prompt = &d_correlator_outs[2]; d_Late = &d_correlator_outs[3]; d_Very_Late = &d_correlator_outs[4]; d_local_code_shift_chips = static_cast(volk_malloc(d_n_correlator_taps * sizeof(float), volk_get_alignment())); // Set TAPs delay values [chips] d_local_code_shift_chips[0] = - d_very_early_late_spc_chips * 2.0; d_local_code_shift_chips[1] = - d_very_early_late_spc_chips; d_local_code_shift_chips[2] = 0.0; d_local_code_shift_chips[3] = d_very_early_late_spc_chips; d_local_code_shift_chips[4] = d_very_early_late_spc_chips * 2.0; d_correlation_length_samples = d_vector_length; multicorrelator_cpu.init(2 * d_correlation_length_samples, d_n_correlator_taps); //--- Initializations ------------------------------ // Initial code frequency basis of NCO d_code_freq_chips = static_cast(Galileo_E1_CODE_CHIP_RATE_HZ); // Residual code phase (in chips) d_rem_code_phase_samples = 0.0; // Residual carrier phase d_rem_carr_phase_rad = 0.0; // sample synchronization d_sample_counter = 0; //d_sample_counter_seconds = 0; d_acq_sample_stamp = 0; 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 = 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["E"] = std::string("Galileo"); *d_Very_Early = gr_complex(0,0); *d_Early = gr_complex(0,0); *d_Prompt = gr_complex(0,0); *d_Late = gr_complex(0,0); *d_Very_Late = gr_complex(0,0); 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_rad = 0.0; d_acc_code_phase_secs = 0.0; } void galileo_e1_dll_pll_veml_tracking_cc::start_tracking() { 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; // DLL/PLL filter initialization d_carrier_loop_filter.initialize(); // initialize the carrier filter d_code_loop_filter.initialize(); // initialize the code filter // generate local reference ALWAYS starting at chip 1 (2 samples per chip) galileo_e1_code_gen_complex_sampled(d_ca_code, d_acquisition_gnss_synchro->Signal, false, d_acquisition_gnss_synchro->PRN, 2 * Galileo_E1_CODE_CHIP_RATE_HZ, 0); multicorrelator_cpu.set_local_code_and_taps(static_cast(2 * Galileo_E1_B_CODE_LENGTH_CHIPS), d_ca_code, d_local_code_shift_chips); for (int n = 0; n < d_n_correlator_taps; n++) { d_correlator_outs[n] = gr_complex(0,0); } d_carrier_lock_fail_counter = 0; d_rem_code_phase_samples = 0.0; d_rem_carr_phase_rad = 0.0; d_acc_carrier_phase_rad = 0.0; d_acc_code_phase_secs = 0.0; d_carrier_doppler_hz = d_acq_carrier_doppler_hz; d_current_prn_length_samples = d_vector_length; 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; LOG(INFO) << "PULL-IN Doppler [Hz]=" << d_carrier_doppler_hz << " PULL-IN Code Phase [samples]=" << d_acq_code_phase_samples; } galileo_e1_dll_pll_veml_tracking_cc::~galileo_e1_dll_pll_veml_tracking_cc() { d_dump_file.close(); volk_free(d_local_code_shift_chips); volk_free(d_correlator_outs); volk_free(d_ca_code); delete[] d_Prompt_buffer; multicorrelator_cpu.free(); } int galileo_e1_dll_pll_veml_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) { double carr_error_hz = 0.0; double carr_error_filt_hz = 0.0; double code_error_chips = 0.0; double code_error_filt_chips = 0.0; // Block input data and block output stream pointers const gr_complex* in = (gr_complex*) input_items[0]; 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(); if (d_enable_tracking == true) { // Fill the acquisition data current_synchro_data = *d_acquisition_gnss_synchro; if (d_pull_in == true) { /* * Signal alignment (skip samples until the incoming signal is aligned with local replica) */ 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_current_prn_length_samples - std::fmod(static_cast(acq_to_trk_delay_samples), static_cast(d_current_prn_length_samples)); samples_offset = std::round(d_acq_code_phase_samples + acq_trk_shif_correction_samples); current_synchro_data.Tracking_timestamp_secs = (static_cast(d_sample_counter) + static_cast(d_rem_code_phase_samples)) / static_cast(d_fs_in); *out[0] = current_synchro_data; d_sample_counter = d_sample_counter + 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; } // ################# CARRIER WIPEOFF AND CORRELATORS ############################## // perform carrier wipe-off and compute Early, Prompt and Late correlation multicorrelator_cpu.set_input_output_vectors(d_correlator_outs,in); double carr_phase_step_rad = GALILEO_TWO_PI * d_carrier_doppler_hz / static_cast(d_fs_in); double code_phase_step_half_chips = (2.0 * d_code_freq_chips) / (static_cast(d_fs_in)); double rem_code_phase_half_chips = d_rem_code_phase_samples * (2.0*d_code_freq_chips / d_fs_in); multicorrelator_cpu.Carrier_wipeoff_multicorrelator_resampler( d_rem_carr_phase_rad, carr_phase_step_rad, rem_code_phase_half_chips, code_phase_step_half_chips, d_correlation_length_samples); // ################## PLL ########################################################## // PLL discriminator carr_error_hz = pll_cloop_two_quadrant_atan(*d_Prompt) / GALILEO_TWO_PI; // Carrier discriminator filter carr_error_filt_hz = d_carrier_loop_filter.get_carrier_nco(carr_error_hz); // New carrier Doppler frequency estimation d_carrier_doppler_hz = d_acq_carrier_doppler_hz + carr_error_filt_hz; // New code Doppler frequency estimation d_code_freq_chips = Galileo_E1_CODE_CHIP_RATE_HZ + ((d_carrier_doppler_hz * Galileo_E1_CODE_CHIP_RATE_HZ) / Galileo_E1_FREQ_HZ); //carrier phase accumulator for (K) Doppler estimation- d_acc_carrier_phase_rad -= GALILEO_TWO_PI * d_carrier_doppler_hz * static_cast(d_current_prn_length_samples) / static_cast(d_fs_in); //remnant carrier phase to prevent overflow in the code NCO d_rem_carr_phase_rad = d_rem_carr_phase_rad + GALILEO_TWO_PI * d_carrier_doppler_hz * static_cast(d_current_prn_length_samples) / static_cast(d_fs_in); d_rem_carr_phase_rad = std::fmod(d_rem_carr_phase_rad, GALILEO_TWO_PI); // ################## DLL ########################################################## // DLL discriminator code_error_chips = dll_nc_vemlp_normalized(*d_Very_Early, *d_Early, *d_Late, *d_Very_Late); //[chips/Ti] // Code discriminator filter code_error_filt_chips = d_code_loop_filter.get_code_nco(code_error_chips); //[chips/second] //Code phase accumulator double code_error_filt_secs; code_error_filt_secs = (Galileo_E1_CODE_PERIOD * code_error_filt_chips) / Galileo_E1_CODE_CHIP_RATE_HZ; //[seconds] //code_error_filt_secs=T_prn_seconds*code_error_filt_chips*T_chip_seconds*static_cast(d_fs_in); //[seconds] d_acc_code_phase_secs = d_acc_code_phase_secs + code_error_filt_secs; // ################## CARRIER AND CODE NCO BUFFER ALIGNEMENT ####################### // keep alignment parameters for the next input buffer double T_chip_seconds; double T_prn_seconds; double T_prn_samples; double K_blk_samples; // Compute the next buffer length based in the new period of the PRN sequence and the code phase error estimation T_chip_seconds = 1.0 / d_code_freq_chips; T_prn_seconds = T_chip_seconds * Galileo_E1_B_CODE_LENGTH_CHIPS; T_prn_samples = T_prn_seconds * static_cast(d_fs_in); K_blk_samples = T_prn_samples + d_rem_code_phase_samples + code_error_filt_secs * static_cast(d_fs_in); d_current_prn_length_samples = std::round(K_blk_samples); //round to a discrete samples //d_rem_code_phase_samples = K_blk_samples - d_current_prn_length_samples; //rounding error < 1 sample // ####### 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] = *d_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, Galileo_E1_B_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 << "!"; pmt::pmt_t value = pmt::from_long(3);//3 -> loss of lock this->message_port_pub(pmt::mp("events"), value); // std::unique_ptr cmf(new ControlMessageFactory()); // if (d_queue != gr::msg_queue::sptr()) // { // d_queue->handle(cmf->GetQueueMessage(d_channel, 2)); // } 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 results to Telemetry block ########## current_synchro_data.Prompt_I = static_cast((*d_Prompt).real()); current_synchro_data.Prompt_Q = static_cast((*d_Prompt).imag()); // Tracking_timestamp_secs is aligned with the CURRENT PRN start sample (Hybridization OK!) current_synchro_data.Tracking_timestamp_secs = (static_cast(d_sample_counter) + static_cast(d_rem_code_phase_samples)) / static_cast(d_fs_in); //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 // This tracking block aligns the Tracking_timestamp_secs with the start sample of the PRN, thus, Code_phase_secs=0 current_synchro_data.Code_phase_secs = 0; current_synchro_data.Carrier_phase_rads = d_acc_carrier_phase_rad; 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; current_synchro_data.correlation_length_ms = 4; } else { *d_Early = gr_complex(0,0); *d_Prompt = gr_complex(0,0); *d_Late = gr_complex(0,0); // GNSS_SYNCHRO OBJECT to interchange data between tracking->telemetry_decoder current_synchro_data.Tracking_timestamp_secs = (static_cast(d_sample_counter) + static_cast(d_rem_code_phase_samples)) / static_cast(d_fs_in); } //assign the GNURadio block output data current_synchro_data.System = {'E'}; std::string str_aux = "1B"; const char * str = str_aux.c_str(); // get a C style null terminated string std::memcpy((void*)current_synchro_data.Signal, str, 3); *out[0] = current_synchro_data; if(d_dump) { // Dump results to file float prompt_I; float prompt_Q; float tmp_VE, tmp_E, tmp_P, tmp_L, tmp_VL; float tmp_float; double tmp_double; prompt_I = (*d_Prompt).real(); prompt_Q = (*d_Prompt).imag(); tmp_VE = std::abs(*d_Very_Early); tmp_E = std::abs(*d_Early); tmp_P = std::abs(*d_Prompt); tmp_L = std::abs(*d_Late); tmp_VL = std::abs(*d_Very_Late); 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(unsigned long int)); // accumulated carrier phase tmp_float = d_acc_carrier_phase_rad; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // carrier and code frequency tmp_float = d_carrier_doppler_hz; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = d_code_freq_chips; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); //PLL commands tmp_float = carr_error_hz; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = carr_error_filt_hz; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); //DLL commands tmp_float = code_error_chips; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = code_error_filt_chips; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // CN0 and carrier lock test tmp_float = d_CN0_SNV_dB_Hz; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_float = d_carrier_lock_test; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); // AUX vars (for debug purposes) tmp_float = d_rem_code_phase_samples; d_dump_file.write(reinterpret_cast(&tmp_float), sizeof(float)); tmp_double = static_cast(d_sample_counter + d_current_prn_length_samples); d_dump_file.write(reinterpret_cast(&tmp_double), sizeof(double)); } catch (const std::ifstream::failure &e) { LOG(WARNING) << "Exception writing trk dump file " << e.what() << std::endl; } } consume_each(d_current_prn_length_samples); // this is required for gr_block derivates d_sample_counter += d_current_prn_length_samples; //count for the processed samples return 1; //output tracking result ALWAYS even in the case of d_enable_tracking==false } void galileo_e1_dll_pll_veml_tracking_cc::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(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() << std::endl; } } } } void galileo_e1_dll_pll_veml_tracking_cc::set_gnss_synchro(Gnss_Synchro* p_gnss_synchro) { d_acquisition_gnss_synchro = p_gnss_synchro; }