/*! * \file gps_l1_ca_dll_fll_pll_tracking_cc.cc * \brief Implementation of a code DLL + carrier FLL/PLL tracking block * \author Javier Arribas, 2011. jarribas(at)cttc.es * * This file implements the code Delay Locked Loop (DLL) + carrier * Phase Locked Loop (PLL) helped with a carrier Frequency Locked Loop (FLL) * according to the algorithms described in: * E.D. Kaplan and C. Hegarty, Understanding GPS. Principles and * Applications, Second Edition, Artech House Publishers, 2005. * * ------------------------------------------------------------------------- * * Copyright (C) 2010-2011 (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 "gnss_synchro.h" #include "gps_l1_ca_dll_fll_pll_tracking_cc.h" //#include "gnss_signal_processing.h" #include "gps_sdr_signal_processing.h" #include "GPS_L1_CA.h" #include "tracking_discriminators.h" #include "CN_estimators.h" #include "tracking_FLL_PLL_filter.h" #include "control_message_factory.h" #include "gnss_flowgraph.h" #include #include #include #include #include "math.h" #include #include #include /*! * \todo Include in definition header file */ #define CN0_ESTIMATION_SAMPLES 10 #define MINIMUM_VALID_CN0 25 #define MAXIMUM_LOCK_FAIL_COUNTER 200 using google::LogMessage; gps_l1_ca_dll_fll_pll_tracking_cc_sptr gps_l1_ca_dll_fll_pll_make_tracking_cc( long if_freq, long fs_in, unsigned int vector_length, gr_msg_queue_sptr queue, bool dump, std::string dump_filename, int order, float fll_bw_hz, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips) { return gps_l1_ca_dll_fll_pll_tracking_cc_sptr(new Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc(if_freq, fs_in, vector_length, queue, dump, dump_filename, order, fll_bw_hz, pll_bw_hz,dll_bw_hz, early_late_space_chips)); } void Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::forecast (int noutput_items, gr_vector_int &ninput_items_required) { ninput_items_required[0] = d_vector_length*2; //set the required available samples in each call } Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc( long if_freq, long fs_in, unsigned int vector_length, gr_msg_queue_sptr queue, bool dump, std::string dump_filename, int order, float fll_bw_hz, float pll_bw_hz, float dll_bw_hz, float early_late_space_chips) : gr_block ("Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc", gr_make_io_signature (1, 1, sizeof(gr_complex)), gr_make_io_signature(1, 1, sizeof(Gnss_Synchro))) { // initialize internal vars d_queue = queue; d_dump = dump; d_acquisition_gnss_synchro=NULL; d_if_freq = (double)if_freq; d_fs_in = (double)fs_in; d_vector_length = vector_length; d_early_late_spc_chips = (double)early_late_space_chips; // Define early-late offset (in chips) d_dump_filename = dump_filename; // Initialize tracking variables ========================================== d_carrier_loop_filter.set_params(fll_bw_hz,pll_bw_hz,order); // Get space for a vector with the C/A code replica sampled 1x/chip d_ca_code = new gr_complex[(int)GPS_L1_CA_CODE_LENGTH_CHIPS + 2]; /* If an array is partitioned for more than one thread to operate on, * having the sub-array boundaries unaligned to cache lines could lead * to performance degradation. Here we allocate memory * (gr_comlex array of size 2*d_vector_length) aligned to cache of 16 bytes */ // todo: do something if posix_memalign fails // Get space for the resampled early / prompt / late local replicas if (posix_memalign((void**)&d_early_code, 16, d_vector_length * sizeof(gr_complex) * 2) == 0){}; if (posix_memalign((void**)&d_late_code, 16, d_vector_length * sizeof(gr_complex) * 2) == 0){}; if (posix_memalign((void**)&d_prompt_code, 16, d_vector_length * sizeof(gr_complex) * 2) == 0){}; // space for carrier wipeoff and signal baseband vectors if (posix_memalign((void**)&d_carr_sign, 16, d_vector_length * sizeof(gr_complex) * 2) == 0){}; // correlator outputs (scalar) if (posix_memalign((void**)&d_Early, 16, sizeof(gr_complex)) == 0){}; if (posix_memalign((void**)&d_Prompt, 16, sizeof(gr_complex)) == 0){}; if (posix_memalign((void**)&d_Late, 16, sizeof(gr_complex)) == 0){}; // sample synchronization d_sample_counter = 0; d_acq_sample_stamp = 0; d_last_seg = 0;// this is for debug output only d_code_phase_samples=0; d_enable_tracking = false; d_current_prn_length_samples = (int)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 = 20; 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"); } void Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::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; unsigned long int acq_trk_diff_samples; double acq_trk_diff_seconds; acq_trk_diff_samples = d_sample_counter - d_acq_sample_stamp;//-d_vector_length; acq_trk_diff_seconds = (double)acq_trk_diff_samples / d_fs_in; //doppler effect // Fd=(C/(C+Vr))*F double radial_velocity; 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_hz = radial_velocity * GPS_L1_CA_CODE_RATE_HZ; T_chip_mod_seconds = 1 / d_code_freq_hz; T_prn_mod_seconds = T_chip_mod_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS; T_prn_mod_samples = T_prn_mod_seconds * d_fs_in; d_current_prn_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 * d_fs_in; double T_prn_diff_seconds; T_prn_diff_seconds = T_prn_true_seconds - T_prn_mod_seconds; double N_prn_diff; 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 * 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; // DLL/PLL filter initialization d_carrier_loop_filter.initialize(d_acq_carrier_doppler_hz); d_FLL_wait = 1; // generate local reference ALWAYS starting at chip 1 (1 sample per chip) gps_l1_ca_code_gen_complex(&d_ca_code[1], d_acquisition_gnss_synchro->PRN, 0); d_ca_code[0] = d_ca_code[(int)GPS_L1_CA_CODE_LENGTH_CHIPS]; d_ca_code[(int)GPS_L1_CA_CODE_LENGTH_CHIPS + 1] = d_ca_code[1]; d_carrier_lock_fail_counter = 0; d_Prompt_prev = 0; d_rem_code_phase_samples = 0; d_rem_carr_phase = 0; d_FLL_discriminator_hz = 0; d_rem_code_phase_samples = 0; d_acc_carrier_phase_rad = 0; 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; DLOG(INFO) << "Start tracking for satellite " << d_acquisition_gnss_synchro->System << " "<< d_acquisition_gnss_synchro->PRN << " received "; // enable tracking Gnss_Satellite(systemName[&d_acquisition_gnss_synchro->System], d_acquisition_gnss_synchro->PRN) d_pull_in = true; d_enable_tracking = true; std::cout << "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 << std::endl; } void Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::update_local_code() { double tcode_chips; double rem_code_phase_chips; double code_phase_step_chips; int associated_chip_index; int code_length_chips = (int)GPS_L1_CA_CODE_LENGTH_CHIPS; code_phase_step_chips = d_code_freq_hz / d_fs_in; rem_code_phase_chips = d_rem_code_phase_samples * (d_code_freq_hz / d_fs_in); // unified loop for E, P, L code vectors tcode_chips = -rem_code_phase_chips; for (int i=0; itelemetry_decoder Gnss_Synchro current_synchro_data; // 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_current_prn_length_samples - fmod((double)acq_to_trk_delay_samples, (double)d_current_prn_length_samples); samples_offset = round(d_acq_code_phase_samples + acq_trk_shif_correction_samples); // /todo: Check if the sample counter sent to the next block as a time reference should be incremented AFTER sended or BEFORE 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 // make an output to not stop the rest of the processing blocks current_synchro_data.Prompt_I=0.0; current_synchro_data.Prompt_Q=0.0; current_synchro_data.Tracking_timestamp_secs=(double)d_sample_counter/d_fs_in; current_synchro_data.Carrier_phase_rads=0.0; current_synchro_data.Code_phase_secs=0.0; current_synchro_data.CN0_dB_hz=0.0; current_synchro_data.Flag_valid_tracking=false; *out[0] =current_synchro_data; return 1; } update_local_code(); update_local_carrier(); // perform Early, Prompt and Late correlation d_correlator.Carrier_wipeoff_and_EPL_volk(d_current_prn_length_samples, in, d_carr_sign, d_early_code, d_prompt_code, d_late_code, d_Early, d_Prompt, d_Late); // check for samples consistency (this should be done before in the receiver / here only if the source is a file) if (std::isnan((*d_Prompt).real()) == true or std::isnan((*d_Prompt).imag()) == true )// or std::isinf(in[i].real())==true or std::isinf(in[i].imag())==true) { const int samples_available = ninput_items[0]; d_sample_counter = d_sample_counter + samples_available; LOG_AT_LEVEL(WARNING) << "Detected NaN samples at sample number " << d_sample_counter; consume_each(samples_available); // make an output to not stop the rest of the processing blocks current_synchro_data.Prompt_I=0.0; current_synchro_data.Prompt_Q=0.0; current_synchro_data.Tracking_timestamp_secs=(double)d_sample_counter/d_fs_in; current_synchro_data.Carrier_phase_rads=0.0; current_synchro_data.Code_phase_secs=0.0; current_synchro_data.CN0_dB_hz=0.0; current_synchro_data.Flag_valid_tracking=false; *out[0] =current_synchro_data; return 1; } /* * DLL, FLL, and PLL discriminators */ // Compute DLL error code_error_chips = dll_nc_e_minus_l_normalized(*d_Early,*d_Late); //compute FLL error correlation_time_s = ((double)d_current_prn_length_samples) / d_fs_in; if (d_FLL_wait == 1) { d_Prompt_prev = *d_Prompt; d_FLL_wait = 0; } else { d_FLL_discriminator_hz = fll_four_quadrant_atan(d_Prompt_prev, *d_Prompt, 0, correlation_time_s) / GPS_TWO_PI; d_Prompt_prev = *d_Prompt; d_FLL_wait = 1; } // Compute PLL error PLL_discriminator_hz = pll_cloop_two_quadrant_atan(*d_Prompt) / GPS_TWO_PI; /* * \todo Update FLL assistance algorithm! */ if ((((double)d_sample_counter - (double)d_acq_sample_stamp) / d_fs_in) > 3) { d_FLL_discriminator_hz = 0; //disconnect the FLL after the initial lock } /* * DLL and FLL+PLL filter and get current carrier Doppler and code frequency */ carr_nco_hz = d_carrier_loop_filter.get_carrier_error(d_FLL_discriminator_hz, PLL_discriminator_hz, correlation_time_s); d_carrier_doppler_hz = d_if_freq + carr_nco_hz; d_code_freq_hz = GPS_L1_CA_CODE_RATE_HZ - (((d_carrier_doppler_hz - d_if_freq) * GPS_L1_CA_CODE_RATE_HZ) / GPS_L1_FREQ_HZ) - code_error_chips; /*! * \todo Improve the lock detection algorithm! */ // ####### 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; d_CN0_SNV_dB_Hz = gps_l1_ca_CN0_SNV(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES, d_fs_in); d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer, CN0_ESTIMATION_SAMPLES); // ###### TRACKING UNLOCK NOTIFICATION ##### if (std::abs(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 << "Channel " << d_channel << " loss of lock!" << std::endl; ControlMessageFactory* cmf = new ControlMessageFactory(); if (d_queue != gr_msg_queue_sptr()) { d_queue->handle(cmf->GetQueueMessage(d_channel, 2)); } delete cmf; d_carrier_lock_fail_counter = 0; d_enable_tracking = false; // TODO: check if disabling tracking is consistent with the channel state machine } } // ########## DEBUG OUTPUT /*! * \todo The stop timer has to be moved to the signal source! */ // debug: Second counter in channel 0 if (d_channel == 0) { if (floor(d_sample_counter/d_fs_in) != d_last_seg) { d_last_seg = floor(d_sample_counter/d_fs_in); std::cout << "Current input signal time = " << d_last_seg << " [s]" << std::endl; std::cout << "Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << ", CN0 = " << d_CN0_SNV_dB_Hz << " [dB-Hz]" << std::endl; } } else { if (floor(d_sample_counter/d_fs_in) != d_last_seg) { d_last_seg = floor(d_sample_counter/d_fs_in); std::cout << "Tracking CH " << d_channel << ": Satellite " << Gnss_Satellite(systemName[sys], d_acquisition_gnss_synchro->PRN) << ", CN0 = " << d_CN0_SNV_dB_Hz << " [dB-Hz]" << std::endl; } } //predict the next loop PRN period length prediction double T_chip_seconds; double T_prn_seconds; double T_prn_samples; double K_blk_samples; T_chip_seconds = 1/d_code_freq_hz; T_prn_seconds = T_chip_seconds * GPS_L1_CA_CODE_LENGTH_CHIPS; T_prn_samples = T_prn_seconds * d_fs_in; K_blk_samples = T_prn_samples + d_rem_code_phase_samples; d_current_prn_length_samples = round(K_blk_samples); //round to a discrete sample d_rem_code_phase_samples = K_blk_samples - d_current_prn_length_samples; //rounding error // ########### Output the tracking data to navigation and PVT ########## current_synchro_data.Prompt_I=(double)(*d_Prompt).imag(); current_synchro_data.Prompt_Q=(double)(*d_Prompt).real(); // Tracking_timestamp_secs is aligned with the PRN start sample current_synchro_data.Tracking_timestamp_secs=((double)d_sample_counter+(double)d_current_prn_length_samples+d_rem_code_phase_samples)/d_fs_in; // This tracking block aligns the Tracking_timestamp_secs with the start sample of the PRN, 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.CN0_dB_hz=d_CN0_SNV_dB_Hz; current_synchro_data.Flag_valid_tracking=true; *out[0] =current_synchro_data; } else { *d_Early = gr_complex(0,0); *d_Prompt = gr_complex(0,0); *d_Late = gr_complex(0,0); Gnss_Synchro **out = (Gnss_Synchro **) &output_items[0]; //block output streams pointer *out[0]=*d_acquisition_gnss_synchro; } if(d_dump) { // MULTIPLEXED FILE RECORDING - Record results to file float prompt_I; float prompt_Q; float tmp_E, tmp_P, tmp_L; float tmp_float; double tmp_double; prompt_I = (*d_Prompt).imag(); prompt_Q = (*d_Prompt).real(); tmp_E=std::abs(*d_Early); tmp_P=std::abs(*d_Prompt); tmp_L=std::abs(*d_Late); try { // EPR d_dump_file.write((char*)&tmp_E, sizeof(float)); d_dump_file.write((char*)&tmp_P, sizeof(float)); d_dump_file.write((char*)&tmp_L, sizeof(float)); // PROMPT I and Q (to analyze navigation symbols) d_dump_file.write((char*)&prompt_I, sizeof(float)); d_dump_file.write((char*)&prompt_Q, sizeof(float)); // PRN start sample stamp //tmp_float=(float)d_sample_counter; d_dump_file.write((char*)&d_sample_counter, sizeof(unsigned long int)); // accumulated carrier phase tmp_float=(float)d_acc_carrier_phase_rad; d_dump_file.write((char*)&tmp_float, sizeof(float)); // carrier and code frequency tmp_float=(float)d_carrier_doppler_hz; d_dump_file.write((char*)&tmp_float, sizeof(float)); tmp_float=(float)d_code_freq_hz; d_dump_file.write((char*)&tmp_float, sizeof(float)); //PLL commands tmp_float=(float)PLL_discriminator_hz; d_dump_file.write((char*)&tmp_float, sizeof(float)); tmp_float=(float)carr_nco_hz; d_dump_file.write((char*)&tmp_float, sizeof(float)); //DLL commands tmp_float=(float)code_error_chips; d_dump_file.write((char*)&tmp_float, sizeof(float)); tmp_float=(float)d_code_phase_samples; d_dump_file.write((char*)&tmp_float, sizeof(float)); // CN0 and carrier lock test tmp_float=(float)d_CN0_SNV_dB_Hz; d_dump_file.write((char*)&tmp_float, sizeof(float)); tmp_float=(float)d_carrier_lock_test; d_dump_file.write((char*)&tmp_float, sizeof(float)); // AUX vars (for debug purposes) tmp_float = (float)d_rem_code_phase_samples; d_dump_file.write((char*)&tmp_float, sizeof(float)); tmp_double=(double)(d_sample_counter+d_current_prn_length_samples); d_dump_file.write((char*)&tmp_double, sizeof(double)); } catch (std::ifstream::failure e) { std::cout << "Exception writing trk dump file "<< e.what() << std::endl; } } consume_each(d_current_prn_length_samples); // this is necesary in 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 Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::set_channel(unsigned int channel) { d_channel = channel; DLOG(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); std::cout << "Tracking dump enabled on channel " << d_channel << " Log file: " << d_dump_filename.c_str() << std::endl; } catch (std::ifstream::failure e) { std::cout << "channel " << d_channel << " Exception opening trk dump file " << e.what() << std::endl; } } } } void Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::set_channel_queue(concurrent_queue *channel_internal_queue) { d_channel_internal_queue = channel_internal_queue; } void Gps_L1_Ca_Dll_Fll_Pll_Tracking_cc::set_gnss_synchro(Gnss_Synchro* p_gnss_synchro) { d_acquisition_gnss_synchro=p_gnss_synchro; }