/*! * \file pcps_acquisition_fine_doppler_cc.cc * \brief This class implements a Parallel Code Phase Search Acquisition with multi-dwells and fine Doppler estimation * \authors * * ----------------------------------------------------------------------------- * * Copyright (C) 2010-2020 (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. * * SPDX-License-Identifier: GPL-3.0-or-later * * ----------------------------------------------------------------------------- */ #include "pcps_acquisition_fine_doppler_cc.h" #include "GPS_L1_CA.h" // for GPS_L1_CA_CHIP_PERIOD_S #include "gnss_sdr_create_directory.h" #include "gnss_sdr_make_unique.h" #include "gps_sdr_signal_processing.h" #if HAS_STD_FILESYSTEM #if HAS_STD_FILESYSTEM_EXPERIMENTAL #include #else #include #endif #else #include #endif #include #include #include #include #include // std::rotate, std::fill_n #include #include #include #if HAS_STD_FILESYSTEM #if HAS_STD_FILESYSTEM_EXPERIMENTAL namespace fs = std::experimental::filesystem; #else namespace fs = std::filesystem; #endif #else namespace fs = boost::filesystem; #endif pcps_acquisition_fine_doppler_cc_sptr pcps_make_acquisition_fine_doppler_cc(const Acq_Conf &conf_) { return pcps_acquisition_fine_doppler_cc_sptr( new pcps_acquisition_fine_doppler_cc(conf_)); } pcps_acquisition_fine_doppler_cc::pcps_acquisition_fine_doppler_cc(const Acq_Conf &conf_) : gr::block("pcps_acquisition_fine_doppler_cc", gr::io_signature::make(1, 1, sizeof(gr_complex)), gr::io_signature::make(0, 1, sizeof(Gnss_Synchro))) { this->message_port_register_out(pmt::mp("events")); acq_parameters = conf_; d_sample_counter = 0ULL; // SAMPLE COUNTER d_active = false; d_fs_in = conf_.fs_in; d_samples_per_ms = static_cast(conf_.samples_per_ms); d_config_doppler_max = conf_.doppler_max; d_fft_size = d_samples_per_ms; // HS Acquisition d_max_dwells = conf_.max_dwells; d_gnuradio_forecast_samples = d_fft_size; d_state = 0; d_fft_codes.reserve(d_fft_size); d_magnitude.reserve(d_fft_size); d_10_ms_buffer.reserve(50 * d_samples_per_ms); // Direct FFT d_fft_if = std::make_unique(d_fft_size, true); // Inverse FFT d_ifft = std::make_unique(d_fft_size, false); // For dumping samples into a file d_dump = conf_.dump; d_dump_filename = conf_.dump_filename; if (d_dump) { std::string dump_path; // Get path if (d_dump_filename.find_last_of('/') != std::string::npos) { std::string dump_filename_ = d_dump_filename.substr(d_dump_filename.find_last_of('/') + 1); dump_path = d_dump_filename.substr(0, d_dump_filename.find_last_of('/')); d_dump_filename = dump_filename_; } else { dump_path = std::string("."); } if (d_dump_filename.empty()) { d_dump_filename = "acquisition"; } // remove extension if any if (d_dump_filename.substr(1).find_last_of('.') != std::string::npos) { d_dump_filename = d_dump_filename.substr(0, d_dump_filename.find_last_of('.')); } d_dump_filename = dump_path + fs::path::preferred_separator + d_dump_filename; // create directory if (!gnss_sdr_create_directory(dump_path)) { std::cerr << "GNSS-SDR cannot create dump file for the Acquisition block. Wrong permissions?\n"; d_dump = false; } } d_n_samples_in_buffer = 0; d_threshold = 0; d_num_doppler_points = 0; d_doppler_step = 0; d_gnss_synchro = nullptr; d_code_phase = 0; d_doppler_freq = 0; d_test_statistics = 0; d_well_count = 0; d_channel = 0; d_positive_acq = 0; d_dump_number = 0; d_dump_channel = 0; // this implementation can only produce dumps in channel 0 // todo: migrate config parameters to the unified acquisition config class } // Finds next power of two // for n. If n itself is a // power of two then returns n unsigned int pcps_acquisition_fine_doppler_cc::nextPowerOf2(unsigned int n) { n--; n |= n >> 1U; n |= n >> 2U; n |= n >> 4U; n |= n >> 8U; n |= n >> 16U; n++; return n; } void pcps_acquisition_fine_doppler_cc::set_doppler_step(unsigned int doppler_step) { d_doppler_step = doppler_step; // Create the search grid array d_num_doppler_points = floor(std::abs(2 * d_config_doppler_max) / d_doppler_step); d_grid_data = volk_gnsssdr::vector>(d_num_doppler_points, volk_gnsssdr::vector(d_fft_size)); if (d_dump) { grid_ = arma::fmat(d_fft_size, d_num_doppler_points, arma::fill::zeros); } update_carrier_wipeoff(); } void pcps_acquisition_fine_doppler_cc::set_local_code(std::complex *code) { memcpy(d_fft_if->get_inbuf(), code, sizeof(gr_complex) * d_fft_size); d_fft_if->execute(); // We need the FFT of local code // Conjugate the local code volk_32fc_conjugate_32fc(d_fft_codes.data(), d_fft_if->get_outbuf(), d_fft_size); } void pcps_acquisition_fine_doppler_cc::init() { d_gnss_synchro->Flag_valid_acquisition = false; d_gnss_synchro->Flag_valid_symbol_output = false; d_gnss_synchro->Flag_valid_pseudorange = false; d_gnss_synchro->Flag_valid_word = false; d_gnss_synchro->Acq_doppler_step = 0U; d_gnss_synchro->Acq_delay_samples = 0.0; d_gnss_synchro->Acq_doppler_hz = 0.0; d_gnss_synchro->Acq_samplestamp_samples = 0ULL; d_state = 0; } void pcps_acquisition_fine_doppler_cc::forecast(int noutput_items, gr_vector_int &ninput_items_required) { if (noutput_items != 0) { ninput_items_required[0] = d_gnuradio_forecast_samples; // set the required available samples in each call } } void pcps_acquisition_fine_doppler_cc::reset_grid() { d_well_count = 0; for (int i = 0; i < d_num_doppler_points; i++) { // todo: use memset here for (int j = 0; j < d_fft_size; j++) { d_grid_data[i][j] = 0.0; } } } void pcps_acquisition_fine_doppler_cc::update_carrier_wipeoff() { // create the carrier Doppler wipeoff signals int doppler_hz; float phase_step_rad; d_grid_doppler_wipeoffs = volk_gnsssdr::vector>>(d_num_doppler_points, volk_gnsssdr::vector>(d_fft_size)); for (int doppler_index = 0; doppler_index < d_num_doppler_points; doppler_index++) { doppler_hz = static_cast(d_doppler_step) * doppler_index - d_config_doppler_max; // doppler search steps // compute the carrier doppler wipe-off signal and store it phase_step_rad = static_cast(TWO_PI) * static_cast(doppler_hz) / static_cast(d_fs_in); float _phase[1]; _phase[0] = 0; volk_gnsssdr_s32f_sincos_32fc(d_grid_doppler_wipeoffs[doppler_index].data(), -phase_step_rad, _phase, d_fft_size); } } float pcps_acquisition_fine_doppler_cc::compute_CAF() { float firstPeak = 0.0; int index_doppler = 0; uint32_t tmp_intex_t = 0; uint32_t index_time = 0; // Look for correlation peaks in the results ============================== // Find the highest peak and compare it to the second highest peak // The second peak is chosen not closer than 1 chip to the highest peak // --- Find the correlation peak and the carrier frequency -------------- for (int i = 0; i < d_num_doppler_points; i++) { volk_gnsssdr_32f_index_max_32u(&tmp_intex_t, d_grid_data[i].data(), d_fft_size); if (d_grid_data[i][tmp_intex_t] > firstPeak) { firstPeak = d_grid_data[i][tmp_intex_t]; index_doppler = i; index_time = tmp_intex_t; } // Record results to file if required if (d_dump and d_channel == d_dump_channel) { memcpy(grid_.colptr(i), d_grid_data[i].data(), sizeof(float) * d_fft_size); } } // -- - Find 1 chip wide code phase exclude range around the peak uint32_t samplesPerChip = ceil(GPS_L1_CA_CHIP_PERIOD_S * static_cast(this->d_fs_in)); int32_t excludeRangeIndex1 = index_time - samplesPerChip; int32_t excludeRangeIndex2 = index_time + samplesPerChip; // -- - Correct code phase exclude range if the range includes array boundaries if (excludeRangeIndex1 < 0) { excludeRangeIndex1 = d_fft_size + excludeRangeIndex1; } else if (excludeRangeIndex2 >= static_cast(d_fft_size)) { excludeRangeIndex2 = excludeRangeIndex2 - d_fft_size; } int32_t idx = excludeRangeIndex1; do { d_grid_data[index_doppler][idx] = 0.0; idx++; if (idx == static_cast(d_fft_size)) { idx = 0; } } while (idx != excludeRangeIndex2); // --- Find the second highest correlation peak in the same freq. bin --- volk_gnsssdr_32f_index_max_32u(&tmp_intex_t, d_grid_data[index_doppler].data(), d_fft_size); float secondPeak = d_grid_data[index_doppler][tmp_intex_t]; // 5- Compute the test statistics and compare to the threshold d_test_statistics = firstPeak / secondPeak; // 4- record the maximum peak and the associated synchronization parameters d_gnss_synchro->Acq_delay_samples = static_cast(index_time); d_gnss_synchro->Acq_doppler_hz = static_cast(index_doppler * d_doppler_step - d_config_doppler_max); d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter; d_gnss_synchro->Acq_doppler_step = d_doppler_step; return d_test_statistics; } float pcps_acquisition_fine_doppler_cc::estimate_input_power(gr_vector_const_void_star &input_items) { const auto *in = reinterpret_cast(input_items[0]); // Get the input samples pointer // Compute the input signal power estimation float power = 0; volk_32fc_magnitude_squared_32f(d_magnitude.data(), in, d_fft_size); volk_32f_accumulator_s32f(&power, d_magnitude.data(), d_fft_size); power /= static_cast(d_fft_size); return power; } int pcps_acquisition_fine_doppler_cc::compute_and_accumulate_grid(gr_vector_const_void_star &input_items) { // initialize acquisition algorithm const auto *in = reinterpret_cast(input_items[0]); // Get the input samples pointer DLOG(INFO) << "Channel: " << d_channel << " , doing acquisition of satellite: " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN << " ,sample stamp: " << d_sample_counter << ", threshold: " << d_threshold << ", doppler_max: " << d_config_doppler_max << ", doppler_step: " << d_doppler_step; // 2- Doppler frequency search loop volk_gnsssdr::vector p_tmp_vector(d_fft_size); for (int doppler_index = 0; doppler_index < d_num_doppler_points; doppler_index++) { // doppler search steps // Perform the carrier wipe-off volk_32fc_x2_multiply_32fc(d_fft_if->get_inbuf(), in, d_grid_doppler_wipeoffs[doppler_index].data(), d_fft_size); // 3- Perform the FFT-based convolution (parallel time search) // Compute the FFT of the carrier wiped--off incoming signal d_fft_if->execute(); // Multiply carrier wiped--off, Fourier transformed incoming signal // with the local FFT'd code reference using SIMD operations with VOLK library volk_32fc_x2_multiply_32fc(d_ifft->get_inbuf(), d_fft_if->get_outbuf(), d_fft_codes.data(), d_fft_size); // compute the inverse FFT d_ifft->execute(); // save the grid matrix delay file volk_32fc_magnitude_squared_32f(p_tmp_vector.data(), d_ifft->get_outbuf(), d_fft_size); // accumulate grid values volk_32f_x2_add_32f(d_grid_data[doppler_index].data(), d_grid_data[doppler_index].data(), p_tmp_vector.data(), d_fft_size); } return d_fft_size; // debug // std::cout << "iff=["; // for (int n = 0; n < d_fft_size; n++) // { // std::cout << std::real(d_ifft->get_outbuf()[n]) << "+" << std::imag(d_ifft->get_outbuf()[n]) << "i,"; // } // std::cout << "]\n"; // getchar(); } int pcps_acquisition_fine_doppler_cc::estimate_Doppler() { // Direct FFT int zero_padding_factor = 8; int prn_replicas = 10; int signal_samples = prn_replicas * d_fft_size; // int fft_size_extended = nextPowerOf2(signal_samples * zero_padding_factor); int fft_size_extended = signal_samples * zero_padding_factor; auto fft_operator = std::make_unique(fft_size_extended, true); // zero padding the entire vector std::fill_n(fft_operator->get_inbuf(), fft_size_extended, gr_complex(0.0, 0.0)); // 1. generate local code aligned with the acquisition code phase estimation volk_gnsssdr::vector code_replica(signal_samples); gps_l1_ca_code_gen_complex_sampled(code_replica, d_gnss_synchro->PRN, d_fs_in, 0); int shift_index = static_cast(d_gnss_synchro->Acq_delay_samples); // Rotate to align the local code replica using acquisition time delay estimation if (shift_index != 0) { std::rotate(code_replica.data(), code_replica.data() + (d_fft_size - shift_index), code_replica.data() + d_fft_size - 1); } for (int n = 0; n < prn_replicas - 1; n++) { memcpy(&code_replica[(n + 1) * d_fft_size], code_replica.data(), d_fft_size * sizeof(gr_complex)); } // 2. Perform code wipe-off volk_32fc_x2_multiply_32fc(fft_operator->get_inbuf(), d_10_ms_buffer.data(), code_replica.data(), signal_samples); // 3. Perform the FFT (zero padded!) fft_operator->execute(); // 4. Compute the magnitude and find the maximum volk_gnsssdr::vector p_tmp_vector(fft_size_extended); volk_32fc_magnitude_squared_32f(p_tmp_vector.data(), fft_operator->get_outbuf(), fft_size_extended); uint32_t tmp_index_freq = 0; volk_gnsssdr_32f_index_max_32u(&tmp_index_freq, p_tmp_vector.data(), fft_size_extended); // case even int counter = 0; volk_gnsssdr::vector fftFreqBins(fft_size_extended); for (int k = 0; k < (fft_size_extended / 2); k++) { fftFreqBins[counter] = ((static_cast(d_fs_in) / 2.0) * static_cast(k)) / (static_cast(fft_size_extended) / 2.0); counter++; } for (int k = fft_size_extended / 2; k > 0; k--) { fftFreqBins[counter] = ((-static_cast(d_fs_in) / 2.0) * static_cast(k)) / (static_cast(fft_size_extended) / 2.0); counter++; } // 5. Update the Doppler estimation in Hz if (std::abs(fftFreqBins[tmp_index_freq] - d_gnss_synchro->Acq_doppler_hz) < 1000) { d_gnss_synchro->Acq_doppler_hz = static_cast(fftFreqBins[tmp_index_freq]); // std::cout << "FFT maximum present at " << fftFreqBins[tmp_index_freq] << " [Hz]\n"; } else { DLOG(INFO) << "Abs(Grid Doppler - FFT Doppler)=" << std::abs(fftFreqBins[tmp_index_freq] - d_gnss_synchro->Acq_doppler_hz); DLOG(INFO) << "Error estimating fine frequency Doppler"; } return d_fft_size; } // Called by gnuradio to enable drivers, etc for i/o devices. bool pcps_acquisition_fine_doppler_cc::start() { d_sample_counter = 0ULL; return true; } void pcps_acquisition_fine_doppler_cc::set_state(int state) { // gr::thread::scoped_lock lock(d_setlock); // require mutex with work function called by the scheduler d_state = state; if (d_state == 1) { d_gnss_synchro->Acq_delay_samples = 0.0; d_gnss_synchro->Acq_doppler_hz = 0.0; d_gnss_synchro->Acq_samplestamp_samples = 0ULL; d_gnss_synchro->Acq_doppler_step = 0U; d_well_count = 0; d_test_statistics = 0.0; d_active = true; reset_grid(); } else if (d_state == 0) { } else { LOG(ERROR) << "State can only be set to 0 or 1"; } } int pcps_acquisition_fine_doppler_cc::general_work(int noutput_items, gr_vector_int &ninput_items __attribute__((unused)), gr_vector_const_void_star &input_items, gr_vector_void_star &output_items) { /*! * TODO: High sensitivity acquisition algorithm: * State Machine: * S0. StandBy. If d_active==1 -> S1 * S1. ComputeGrid. Perform the FFT acqusition doppler and delay grid. * Accumulate the search grid matrix (#doppler_bins x #fft_size) * Compare maximum to threshold and decide positive or negative * If T>=gamma -> S4 else * If d_well_count S2 * else -> S5. * S4. Positive_Acq: Send message and stop acq -> S0 * S5. Negative_Acq: Send message and stop acq -> S0 */ int return_value = 0; // Number of Gnss_Syncro objects produced int samples_remaining; switch (d_state) { case 0: // S0. StandBy if (d_active == true) { reset_grid(); d_n_samples_in_buffer = 0; d_state = 1; } if (!acq_parameters.blocking_on_standby) { d_sample_counter += static_cast(d_fft_size); // sample counter consume_each(d_fft_size); } break; case 1: // S1. ComputeGrid compute_and_accumulate_grid(input_items); memcpy(&d_10_ms_buffer[d_n_samples_in_buffer], reinterpret_cast(input_items[0]), d_fft_size * sizeof(gr_complex)); d_n_samples_in_buffer += d_fft_size; d_well_count++; if (d_well_count >= d_max_dwells) { d_state = 2; } d_sample_counter += static_cast(d_fft_size); // sample counter consume_each(d_fft_size); break; case 2: // Compute test statistics and decide d_test_statistics = compute_CAF(); if (d_test_statistics > d_threshold) { d_state = 3; // perform fine doppler estimation } else { d_state = 5; // negative acquisition d_n_samples_in_buffer = 0; } break; case 3: // Fine doppler estimation samples_remaining = 10 * d_samples_per_ms - d_n_samples_in_buffer; if (samples_remaining > noutput_items) { memcpy(&d_10_ms_buffer[d_n_samples_in_buffer], reinterpret_cast(input_items[0]), noutput_items * sizeof(gr_complex)); d_n_samples_in_buffer += noutput_items; d_sample_counter += static_cast(noutput_items); // sample counter consume_each(noutput_items); } else { if (samples_remaining > 0) { memcpy(&d_10_ms_buffer[d_n_samples_in_buffer], reinterpret_cast(input_items[0]), samples_remaining * sizeof(gr_complex)); d_sample_counter += static_cast(samples_remaining); // sample counter consume_each(samples_remaining); } estimate_Doppler(); // disabled in repo d_n_samples_in_buffer = 0; d_state = 4; } break; case 4: // Positive_Acq DLOG(INFO) << "positive acquisition"; DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN; DLOG(INFO) << "sample_stamp " << d_sample_counter; DLOG(INFO) << "test statistics value " << d_test_statistics; DLOG(INFO) << "test statistics threshold " << d_threshold; DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples; DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz; d_positive_acq = 1; d_active = false; // Record results to file if required if (d_dump and d_channel == d_dump_channel) { dump_results(d_fft_size); } // Send message to channel port //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL this->message_port_pub(pmt::mp("events"), pmt::from_long(1)); d_state = 0; if (!acq_parameters.blocking_on_standby) { d_sample_counter += static_cast(noutput_items); // sample counter consume_each(noutput_items); } // Copy and push current Gnss_Synchro to monitor queue if (acq_parameters.enable_monitor_output) { auto **out = reinterpret_cast(&output_items[0]); Gnss_Synchro current_synchro_data = Gnss_Synchro(); current_synchro_data = *d_gnss_synchro; *out[0] = current_synchro_data; return_value = 1; // Number of Gnss_Synchro objects produced } break; case 5: // Negative_Acq DLOG(INFO) << "negative acquisition"; DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN; DLOG(INFO) << "sample_stamp " << d_sample_counter; DLOG(INFO) << "test statistics value " << d_test_statistics; DLOG(INFO) << "test statistics threshold " << d_threshold; DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples; DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz; d_positive_acq = 0; d_active = false; // Record results to file if required if (d_dump and d_channel == d_dump_channel) { dump_results(d_fft_size); } // Send message to channel port //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL this->message_port_pub(pmt::mp("events"), pmt::from_long(2)); d_state = 0; if (!acq_parameters.blocking_on_standby) { d_sample_counter += static_cast(noutput_items); // sample counter consume_each(noutput_items); } break; default: d_state = 0; if (!acq_parameters.blocking_on_standby) { d_sample_counter += static_cast(noutput_items); // sample counter consume_each(noutput_items); } break; } return return_value; } void pcps_acquisition_fine_doppler_cc::dump_results(int effective_fft_size) { d_dump_number++; std::string filename = d_dump_filename; filename.append("_"); filename.append(1, d_gnss_synchro->System); filename.append("_"); filename.append(1, d_gnss_synchro->Signal[0]); filename.append(1, d_gnss_synchro->Signal[1]); filename.append("_ch_"); filename.append(std::to_string(d_channel)); filename.append("_"); filename.append(std::to_string(d_dump_number)); filename.append("_sat_"); filename.append(std::to_string(d_gnss_synchro->PRN)); filename.append(".mat"); mat_t *matfp = Mat_CreateVer(filename.c_str(), nullptr, MAT_FT_MAT73); if (matfp == nullptr) { std::cout << "Unable to create or open Acquisition dump file\n"; d_dump = false; } else { std::array dims{static_cast(effective_fft_size), static_cast(d_num_doppler_points)}; matvar_t *matvar = Mat_VarCreate("acq_grid", MAT_C_SINGLE, MAT_T_SINGLE, 2, dims.data(), grid_.memptr(), 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); dims[0] = static_cast(1); dims[1] = static_cast(1); matvar = Mat_VarCreate("doppler_max", MAT_C_INT32, MAT_T_INT32, 1, dims.data(), &d_config_doppler_max, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("doppler_step", MAT_C_INT32, MAT_T_INT32, 1, dims.data(), &d_doppler_step, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("d_positive_acq", MAT_C_INT32, MAT_T_INT32, 1, dims.data(), &d_positive_acq, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); auto aux = static_cast(d_gnss_synchro->Acq_doppler_hz); matvar = Mat_VarCreate("acq_doppler_hz", MAT_C_SINGLE, MAT_T_SINGLE, 1, dims.data(), &aux, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); aux = static_cast(d_gnss_synchro->Acq_delay_samples); matvar = Mat_VarCreate("acq_delay_samples", MAT_C_SINGLE, MAT_T_SINGLE, 1, dims.data(), &aux, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("test_statistic", MAT_C_SINGLE, MAT_T_SINGLE, 1, dims.data(), &d_test_statistics, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("threshold", MAT_C_SINGLE, MAT_T_SINGLE, 1, dims.data(), &d_threshold, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); aux = 0.0; matvar = Mat_VarCreate("input_power", MAT_C_SINGLE, MAT_T_SINGLE, 1, dims.data(), &aux, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("sample_counter", MAT_C_UINT64, MAT_T_UINT64, 1, dims.data(), &d_sample_counter, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); matvar = Mat_VarCreate("PRN", MAT_C_UINT32, MAT_T_UINT32, 1, dims.data(), &d_gnss_synchro->PRN, 0); Mat_VarWrite(matfp, matvar, MAT_COMPRESSION_ZLIB); // or MAT_COMPRESSION_NONE Mat_VarFree(matvar); Mat_Close(matfp); } }