mirror of https://github.com/gnss-sdr/gnss-sdr
369 lines
12 KiB
C++
369 lines
12 KiB
C++
/*!
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* \file gps_l5i_pcps_acquisition.cc
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* \brief Adapts a PCPS acquisition block to an Acquisition Interface for
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* GPS L5i signals
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* \authors <ul>
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* <li> Javier Arribas, 2017. jarribas(at)cttc.es
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* </ul>
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2018 (see AUTHORS file for a list of contributors)
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*
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* GNSS-SDR is a software defined Global Navigation
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* Satellite Systems receiver
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*
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* This file is part of GNSS-SDR.
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*
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* GNSS-SDR is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GNSS-SDR is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNSS-SDR. If not, see <https://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#include "gps_l5i_pcps_acquisition.h"
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#include "GPS_L5.h"
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#include "acq_conf.h"
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#include "configuration_interface.h"
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#include "gnss_sdr_flags.h"
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#include "gps_l5_signal.h"
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#include <boost/math/distributions/exponential.hpp>
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#include <glog/logging.h>
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#include <algorithm>
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GpsL5iPcpsAcquisition::GpsL5iPcpsAcquisition(
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ConfigurationInterface* configuration,
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const std::string& role,
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unsigned int in_streams,
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unsigned int out_streams) : role_(role),
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in_streams_(in_streams),
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out_streams_(out_streams)
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{
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configuration_ = configuration;
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std::string default_item_type = "gr_complex";
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std::string default_dump_filename = "./acquisition.mat";
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LOG(INFO) << "role " << role;
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item_type_ = configuration_->property(role + ".item_type", default_item_type);
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int64_t fs_in_deprecated = configuration_->property("GNSS-SDR.internal_fs_hz", 2048000);
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fs_in_ = configuration_->property("GNSS-SDR.internal_fs_sps", fs_in_deprecated);
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acq_parameters_.fs_in = fs_in_;
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dump_ = configuration_->property(role + ".dump", false);
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acq_parameters_.dump = dump_;
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acq_parameters_.dump_channel = configuration_->property(role + ".dump_channel", 0);
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blocking_ = configuration_->property(role + ".blocking", true);
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acq_parameters_.blocking = blocking_;
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doppler_max_ = configuration->property(role + ".doppler_max", 5000);
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if (FLAGS_doppler_max != 0)
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{
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doppler_max_ = FLAGS_doppler_max;
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}
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acq_parameters_.doppler_max = doppler_max_;
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bit_transition_flag_ = configuration_->property(role + ".bit_transition_flag", false);
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acq_parameters_.bit_transition_flag = bit_transition_flag_;
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use_CFAR_algorithm_flag_ = configuration_->property(role + ".use_CFAR_algorithm", true); //will be false in future versions
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acq_parameters_.use_CFAR_algorithm_flag = use_CFAR_algorithm_flag_;
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max_dwells_ = configuration_->property(role + ".max_dwells", 1);
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acq_parameters_.max_dwells = max_dwells_;
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dump_filename_ = configuration_->property(role + ".dump_filename", default_dump_filename);
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acq_parameters_.dump_filename = dump_filename_;
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acq_parameters_.sampled_ms = configuration_->property(role + ".coherent_integration_time_ms", 1);
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if (item_type_ == "cshort")
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{
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item_size_ = sizeof(lv_16sc_t);
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}
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else
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{
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item_size_ = sizeof(gr_complex);
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}
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acq_parameters_.ms_per_code = 1;
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acq_parameters_.it_size = item_size_;
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num_codes_ = acq_parameters_.sampled_ms;
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acq_parameters_.num_doppler_bins_step2 = configuration_->property(role + ".second_nbins", 4);
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acq_parameters_.doppler_step2 = configuration_->property(role + ".second_doppler_step", 125.0);
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acq_parameters_.make_2_steps = configuration_->property(role + ".make_two_steps", false);
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acq_parameters_.blocking_on_standby = configuration_->property(role + ".blocking_on_standby", false);
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acq_parameters_.use_automatic_resampler = configuration_->property("GNSS-SDR.use_acquisition_resampler", false);
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if (acq_parameters_.use_automatic_resampler == true and item_type_ != "gr_complex")
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{
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LOG(WARNING) << "GPS L5 acquisition disabled the automatic resampler feature because its item_type is not set to gr_complex";
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acq_parameters_.use_automatic_resampler = false;
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}
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if (acq_parameters_.use_automatic_resampler)
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{
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if (acq_parameters_.fs_in > GPS_L5_OPT_ACQ_FS_HZ)
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{
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acq_parameters_.resampler_ratio = floor(static_cast<float>(acq_parameters_.fs_in) / GPS_L5_OPT_ACQ_FS_HZ);
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uint32_t decimation = acq_parameters_.fs_in / GPS_L5_OPT_ACQ_FS_HZ;
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while (acq_parameters_.fs_in % decimation > 0)
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{
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decimation--;
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};
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acq_parameters_.resampler_ratio = decimation;
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acq_parameters_.resampled_fs = acq_parameters_.fs_in / static_cast<int>(acq_parameters_.resampler_ratio);
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}
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//--- Find number of samples per spreading code -------------------------
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code_length_ = static_cast<unsigned int>(std::floor(static_cast<double>(acq_parameters_.resampled_fs) / (GPS_L5I_CODE_RATE_HZ / GPS_L5I_CODE_LENGTH_CHIPS)));
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acq_parameters_.samples_per_ms = static_cast<float>(acq_parameters_.resampled_fs) * 0.001;
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acq_parameters_.samples_per_chip = static_cast<unsigned int>(ceil((1.0 / GPS_L5I_CODE_RATE_HZ) * static_cast<float>(acq_parameters_.resampled_fs)));
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}
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else
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{
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acq_parameters_.resampled_fs = fs_in_;
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//--- Find number of samples per spreading code -------------------------
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code_length_ = static_cast<unsigned int>(std::floor(static_cast<double>(fs_in_) / (GPS_L5I_CODE_RATE_HZ / GPS_L5I_CODE_LENGTH_CHIPS)));
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acq_parameters_.samples_per_ms = static_cast<float>(fs_in_) * 0.001;
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acq_parameters_.samples_per_chip = static_cast<unsigned int>(ceil((1.0 / GPS_L5I_CODE_RATE_HZ) * static_cast<float>(acq_parameters_.fs_in)));
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}
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acq_parameters_.samples_per_code = acq_parameters_.samples_per_ms * static_cast<float>(GPS_L5I_PERIOD * 1000.0);
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vector_length_ = std::floor(acq_parameters_.sampled_ms * acq_parameters_.samples_per_ms) * (acq_parameters_.bit_transition_flag ? 2 : 1);
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code_ = std::vector<std::complex<float>>(vector_length_);
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acquisition_ = pcps_make_acquisition(acq_parameters_);
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DLOG(INFO) << "acquisition(" << acquisition_->unique_id() << ")";
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if (item_type_ == "cbyte")
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{
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cbyte_to_float_x2_ = make_complex_byte_to_float_x2();
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float_to_complex_ = gr::blocks::float_to_complex::make();
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}
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channel_ = 0;
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threshold_ = 0.0;
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doppler_step_ = 0;
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doppler_center_ = 0;
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gnss_synchro_ = nullptr;
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if (in_streams_ > 1)
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{
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LOG(ERROR) << "This implementation only supports one input stream";
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}
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if (out_streams_ > 0)
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{
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LOG(ERROR) << "This implementation does not provide an output stream";
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}
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}
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void GpsL5iPcpsAcquisition::stop_acquisition()
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{
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}
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void GpsL5iPcpsAcquisition::set_threshold(float threshold)
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{
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float pfa = configuration_->property(role_ + std::to_string(channel_) + ".pfa", 0.0);
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if (pfa == 0.0)
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{
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pfa = configuration_->property(role_ + ".pfa", 0.0);
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}
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if (pfa == 0.0)
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{
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threshold_ = threshold;
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}
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else
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{
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threshold_ = calculate_threshold(pfa);
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}
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DLOG(INFO) << "Channel " << channel_ << " Threshold = " << threshold_;
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acquisition_->set_threshold(threshold_);
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}
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void GpsL5iPcpsAcquisition::set_doppler_max(unsigned int doppler_max)
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{
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doppler_max_ = doppler_max;
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acquisition_->set_doppler_max(doppler_max_);
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}
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// Be aware that Doppler step should be set to 2/(3T) Hz, where T is the coherent integration time (GPS L2 period is 0.02s)
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// Doppler bin minimum size= 33 Hz
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void GpsL5iPcpsAcquisition::set_doppler_step(unsigned int doppler_step)
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{
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doppler_step_ = doppler_step;
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acquisition_->set_doppler_step(doppler_step_);
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}
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void GpsL5iPcpsAcquisition::set_doppler_center(int doppler_center)
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{
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doppler_center_ = doppler_center;
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acquisition_->set_doppler_center(doppler_center_);
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}
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void GpsL5iPcpsAcquisition::set_gnss_synchro(Gnss_Synchro* gnss_synchro)
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{
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gnss_synchro_ = gnss_synchro;
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acquisition_->set_gnss_synchro(gnss_synchro_);
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}
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signed int GpsL5iPcpsAcquisition::mag()
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{
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return acquisition_->mag();
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}
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void GpsL5iPcpsAcquisition::init()
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{
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acquisition_->init();
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}
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void GpsL5iPcpsAcquisition::set_local_code()
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{
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std::vector<std::complex<float>> code(code_length_);
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if (acq_parameters_.use_automatic_resampler)
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{
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gps_l5i_code_gen_complex_sampled(code, gnss_synchro_->PRN, acq_parameters_.resampled_fs);
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}
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else
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{
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gps_l5i_code_gen_complex_sampled(code, gnss_synchro_->PRN, fs_in_);
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}
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gsl::span<gr_complex> code_span(code_.data(), vector_length_);
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for (unsigned int i = 0; i < num_codes_; i++)
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{
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std::copy_n(code.data(), code_length_, code_span.subspan(i * code_length_, code_length_).data());
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}
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acquisition_->set_local_code(code_.data());
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}
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void GpsL5iPcpsAcquisition::reset()
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{
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acquisition_->set_active(true);
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}
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void GpsL5iPcpsAcquisition::set_state(int state)
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{
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acquisition_->set_state(state);
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}
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float GpsL5iPcpsAcquisition::calculate_threshold(float pfa)
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{
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//Calculate the threshold
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unsigned int frequency_bins = 0;
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for (int doppler = static_cast<int>(-doppler_max_); doppler <= static_cast<int>(doppler_max_); doppler += doppler_step_)
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{
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frequency_bins++;
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}
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DLOG(INFO) << "Channel " << channel_ << " Pfa = " << pfa;
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unsigned int ncells = vector_length_ * frequency_bins;
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double exponent = 1.0 / static_cast<double>(ncells);
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double val = pow(1.0 - pfa, exponent);
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auto lambda = double(vector_length_);
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boost::math::exponential_distribution<double> mydist(lambda);
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auto threshold = static_cast<float>(quantile(mydist, val));
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return threshold;
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}
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void GpsL5iPcpsAcquisition::connect(gr::top_block_sptr top_block)
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{
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if (item_type_ == "gr_complex")
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{
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// nothing to connect
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}
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else if (item_type_ == "cshort")
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{
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// nothing to connect
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}
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else if (item_type_ == "cbyte")
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{
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// Since a byte-based acq implementation is not available,
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// we just convert cshorts to gr_complex
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top_block->connect(cbyte_to_float_x2_, 0, float_to_complex_, 0);
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top_block->connect(cbyte_to_float_x2_, 1, float_to_complex_, 1);
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top_block->connect(float_to_complex_, 0, acquisition_, 0);
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}
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else
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{
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LOG(WARNING) << item_type_ << " unknown acquisition item type";
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}
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}
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void GpsL5iPcpsAcquisition::disconnect(gr::top_block_sptr top_block)
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{
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if (item_type_ == "gr_complex")
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{
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// nothing to disconnect
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}
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else if (item_type_ == "cshort")
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{
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// nothing to disconnect
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}
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else if (item_type_ == "cbyte")
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{
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top_block->disconnect(cbyte_to_float_x2_, 0, float_to_complex_, 0);
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top_block->disconnect(cbyte_to_float_x2_, 1, float_to_complex_, 1);
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top_block->disconnect(float_to_complex_, 0, acquisition_, 0);
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}
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else
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{
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LOG(WARNING) << item_type_ << " unknown acquisition item type";
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}
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}
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gr::basic_block_sptr GpsL5iPcpsAcquisition::get_left_block()
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{
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if (item_type_ == "gr_complex")
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{
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return acquisition_;
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}
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if (item_type_ == "cshort")
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{
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return acquisition_;
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}
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if (item_type_ == "cbyte")
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{
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return cbyte_to_float_x2_;
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}
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LOG(WARNING) << item_type_ << " unknown acquisition item type";
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return nullptr;
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}
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gr::basic_block_sptr GpsL5iPcpsAcquisition::get_right_block()
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{
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return acquisition_;
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}
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void GpsL5iPcpsAcquisition::set_resampler_latency(uint32_t latency_samples)
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{
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acquisition_->set_resampler_latency(latency_samples);
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}
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