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gnss-sdr/src/algorithms/acquisition/adapters/gps_l2_m_pcps_acquisition.cc

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/*!
* \file gps_l2_m_pcps_acquisition.cc
* \brief Adapts a PCPS acquisition block to an AcquisitionInterface for
* GPS L2 M signals
* \authors <ul>
* <li> Javier Arribas, 2015. jarribas(at)cttc.es
* </ul>
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2018 (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 <https://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "gps_l2_m_pcps_acquisition.h"
#include "GPS_L2C.h"
#include "acq_conf.h"
#include "configuration_interface.h"
#include "gnss_sdr_flags.h"
#include "gps_l2c_signal.h"
#include <boost/math/distributions/exponential.hpp>
#include <glog/logging.h>
#include <algorithm>
GpsL2MPcpsAcquisition::GpsL2MPcpsAcquisition(
ConfigurationInterface* configuration,
const std::string& role,
unsigned int in_streams,
unsigned int out_streams) : role_(role),
in_streams_(in_streams),
out_streams_(out_streams)
{
configuration_ = configuration;
std::string default_item_type = "gr_complex";
std::string default_dump_filename = "./acquisition.mat";
LOG(INFO) << "role " << role;
item_type_ = configuration_->property(role + ".item_type", default_item_type);
int64_t fs_in_deprecated = configuration_->property("GNSS-SDR.internal_fs_hz", 2048000);
fs_in_ = configuration_->property("GNSS-SDR.internal_fs_sps", fs_in_deprecated);
acq_parameters_.fs_in = fs_in_;
dump_ = configuration_->property(role + ".dump", false);
acq_parameters_.dump = dump_;
acq_parameters_.dump_channel = configuration_->property(role + ".dump_channel", 0);
blocking_ = configuration_->property(role + ".blocking", true);
acq_parameters_.blocking = blocking_;
doppler_max_ = configuration->property(role + ".doppler_max", 5000);
if (FLAGS_doppler_max != 0)
{
doppler_max_ = FLAGS_doppler_max;
}
acq_parameters_.doppler_max = doppler_max_;
bit_transition_flag_ = configuration_->property(role + ".bit_transition_flag", false);
acq_parameters_.bit_transition_flag = bit_transition_flag_;
use_CFAR_algorithm_flag_ = configuration_->property(role + ".use_CFAR_algorithm", true); //will be false in future versions
acq_parameters_.use_CFAR_algorithm_flag = use_CFAR_algorithm_flag_;
max_dwells_ = configuration_->property(role + ".max_dwells", 1);
acq_parameters_.max_dwells = max_dwells_;
dump_filename_ = configuration_->property(role + ".dump_filename", default_dump_filename);
acq_parameters_.dump_filename = dump_filename_;
acq_parameters_.ms_per_code = 20;
acq_parameters_.sampled_ms = configuration_->property(role + ".coherent_integration_time_ms", acq_parameters_.ms_per_code);
if ((acq_parameters_.sampled_ms % acq_parameters_.ms_per_code) != 0)
{
LOG(WARNING) << "Parameter coherent_integration_time_ms should be a multiple of 20. Setting it to 20";
acq_parameters_.sampled_ms = acq_parameters_.ms_per_code;
}
acq_parameters_.num_doppler_bins_step2 = configuration_->property(role + ".second_nbins", 4);
acq_parameters_.doppler_step2 = configuration_->property(role + ".second_doppler_step", 125.0);
acq_parameters_.make_2_steps = configuration_->property(role + ".make_two_steps", false);
acq_parameters_.blocking_on_standby = configuration_->property(role + ".blocking_on_standby", false);
acq_parameters_.use_automatic_resampler = configuration_->property("GNSS-SDR.use_acquisition_resampler", false);
if (acq_parameters_.use_automatic_resampler == true and item_type_ != "gr_complex")
{
LOG(WARNING) << "GPS L2CM acquisition disabled the automatic resampler feature because its item_type is not set to gr_complex";
acq_parameters_.use_automatic_resampler = false;
}
if (acq_parameters_.use_automatic_resampler)
{
if (acq_parameters_.fs_in > GPS_L2C_OPT_ACQ_FS_HZ)
{
acq_parameters_.resampler_ratio = floor(static_cast<float>(acq_parameters_.fs_in) / GPS_L2C_OPT_ACQ_FS_HZ);
uint32_t decimation = acq_parameters_.fs_in / GPS_L2C_OPT_ACQ_FS_HZ;
while (acq_parameters_.fs_in % decimation > 0)
{
decimation--;
};
acq_parameters_.resampler_ratio = decimation;
acq_parameters_.resampled_fs = acq_parameters_.fs_in / static_cast<int>(acq_parameters_.resampler_ratio);
}
//--- Find number of samples per spreading code -------------------------
code_length_ = static_cast<unsigned int>(std::floor(static_cast<double>(acq_parameters_.resampled_fs) / (GPS_L2_M_CODE_RATE_HZ / GPS_L2_M_CODE_LENGTH_CHIPS)));
acq_parameters_.samples_per_ms = static_cast<float>(acq_parameters_.resampled_fs) * 0.001;
acq_parameters_.samples_per_chip = static_cast<unsigned int>(ceil((1.0 / GPS_L2_M_CODE_RATE_HZ) * static_cast<float>(acq_parameters_.resampled_fs)));
}
else
{
acq_parameters_.resampled_fs = fs_in_;
//--- Find number of samples per spreading code -------------------------
code_length_ = static_cast<unsigned int>(std::floor(static_cast<double>(fs_in_) / (GPS_L2_M_CODE_RATE_HZ / GPS_L2_M_CODE_LENGTH_CHIPS)));
acq_parameters_.samples_per_ms = static_cast<float>(fs_in_) * 0.001;
acq_parameters_.samples_per_chip = static_cast<unsigned int>(ceil((1.0 / GPS_L2_M_CODE_RATE_HZ) * static_cast<float>(acq_parameters_.fs_in)));
}
acq_parameters_.samples_per_code = acq_parameters_.samples_per_ms * static_cast<float>(GPS_L2_M_PERIOD * 1000.0);
vector_length_ = acq_parameters_.sampled_ms * acq_parameters_.samples_per_ms * (acq_parameters_.bit_transition_flag ? 2 : 1);
code_ = std::vector<std::complex<float>>(vector_length_);
if (item_type_ == "cshort")
{
item_size_ = sizeof(lv_16sc_t);
}
else
{
item_size_ = sizeof(gr_complex);
}
acq_parameters_.it_size = item_size_;
acquisition_ = pcps_make_acquisition(acq_parameters_);
DLOG(INFO) << "acquisition(" << acquisition_->unique_id() << ")";
if (item_type_ == "cbyte")
{
cbyte_to_float_x2_ = make_complex_byte_to_float_x2();
float_to_complex_ = gr::blocks::float_to_complex::make();
}
channel_ = 0;
threshold_ = 0.0;
doppler_step_ = 0;
gnss_synchro_ = nullptr;
num_codes_ = acq_parameters_.sampled_ms / acq_parameters_.ms_per_code;
if (in_streams_ > 1)
{
LOG(ERROR) << "This implementation only supports one input stream";
}
if (out_streams_ > 0)
{
LOG(ERROR) << "This implementation does not provide an output stream";
}
}
GpsL2MPcpsAcquisition::~GpsL2MPcpsAcquisition() = default;
void GpsL2MPcpsAcquisition::stop_acquisition()
{
}
void GpsL2MPcpsAcquisition::set_threshold(float threshold)
{
float pfa = configuration_->property(role_ + std::to_string(channel_) + ".pfa", 0.0);
if (pfa == 0.0)
{
pfa = configuration_->property(role_ + ".pfa", 0.0);
}
if (pfa == 0.0)
{
threshold_ = threshold;
}
else
{
threshold_ = calculate_threshold(pfa);
}
DLOG(INFO) << "Channel " << channel_ << " Threshold = " << threshold_;
acquisition_->set_threshold(threshold_);
}
void GpsL2MPcpsAcquisition::set_doppler_max(unsigned int doppler_max)
{
doppler_max_ = doppler_max;
acquisition_->set_doppler_max(doppler_max_);
}
// 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)
// Doppler bin minimum size= 33 Hz
void GpsL2MPcpsAcquisition::set_doppler_step(unsigned int doppler_step)
{
doppler_step_ = doppler_step;
acquisition_->set_doppler_step(doppler_step_);
}
void GpsL2MPcpsAcquisition::set_gnss_synchro(Gnss_Synchro* gnss_synchro)
{
gnss_synchro_ = gnss_synchro;
acquisition_->set_gnss_synchro(gnss_synchro_);
}
signed int GpsL2MPcpsAcquisition::mag()
{
return acquisition_->mag();
}
void GpsL2MPcpsAcquisition::init()
{
acquisition_->init();
//set_local_code();
}
void GpsL2MPcpsAcquisition::set_local_code()
{
std::unique_ptr<std::complex<float>> code{new std::complex<float>[code_length_]};
if (acq_parameters_.use_automatic_resampler)
{
gps_l2c_m_code_gen_complex_sampled(gsl::span<std::complex<float>>(code.get(), code_length_), gnss_synchro_->PRN, acq_parameters_.resampled_fs);
}
else
{
gps_l2c_m_code_gen_complex_sampled(gsl::span<std::complex<float>>(code.get(), code_length_), gnss_synchro_->PRN, fs_in_);
}
gsl::span<gr_complex> code_span(code_.data(), vector_length_);
for (unsigned int i = 0; i < num_codes_; i++)
{
std::copy_n(code.get(), code_length_, code_span.subspan(i * code_length_, code_length_).data());
}
acquisition_->set_local_code(code_.data());
}
void GpsL2MPcpsAcquisition::reset()
{
acquisition_->set_active(true);
}
void GpsL2MPcpsAcquisition::set_state(int state)
{
acquisition_->set_state(state);
}
float GpsL2MPcpsAcquisition::calculate_threshold(float pfa)
{
//Calculate the threshold
unsigned int frequency_bins = 0;
for (int doppler = static_cast<int>(-doppler_max_); doppler <= static_cast<int>(doppler_max_); doppler += doppler_step_)
{
frequency_bins++;
}
DLOG(INFO) << "Channel " << channel_ << " Pfa = " << pfa;
unsigned int ncells = vector_length_ * frequency_bins;
double exponent = 1.0 / static_cast<double>(ncells);
double val = pow(1.0 - pfa, exponent);
auto lambda = double(vector_length_);
boost::math::exponential_distribution<double> mydist(lambda);
auto threshold = static_cast<float>(quantile(mydist, val));
return threshold;
}
void GpsL2MPcpsAcquisition::connect(gr::top_block_sptr top_block)
{
if (item_type_ == "gr_complex")
{
// nothing to connect
}
else if (item_type_ == "cshort")
{
// nothing to connect
}
else if (item_type_ == "cbyte")
{
// Since a byte-based acq implementation is not available,
// we just convert cshorts to gr_complex
top_block->connect(cbyte_to_float_x2_, 0, float_to_complex_, 0);
top_block->connect(cbyte_to_float_x2_, 1, float_to_complex_, 1);
top_block->connect(float_to_complex_, 0, acquisition_, 0);
}
else
{
LOG(WARNING) << item_type_ << " unknown acquisition item type";
}
}
void GpsL2MPcpsAcquisition::disconnect(gr::top_block_sptr top_block)
{
if (item_type_ == "gr_complex")
{
// nothing to disconnect
}
else if (item_type_ == "cshort")
{
// nothing to disconnect
}
else if (item_type_ == "cbyte")
{
top_block->disconnect(cbyte_to_float_x2_, 0, float_to_complex_, 0);
top_block->disconnect(cbyte_to_float_x2_, 1, float_to_complex_, 1);
top_block->disconnect(float_to_complex_, 0, acquisition_, 0);
}
else
{
LOG(WARNING) << item_type_ << " unknown acquisition item type";
}
}
gr::basic_block_sptr GpsL2MPcpsAcquisition::get_left_block()
{
if (item_type_ == "gr_complex")
{
return acquisition_;
}
if (item_type_ == "cshort")
{
return acquisition_;
}
if (item_type_ == "cbyte")
{
return cbyte_to_float_x2_;
}
LOG(WARNING) << item_type_ << " unknown acquisition item type";
return nullptr;
}
gr::basic_block_sptr GpsL2MPcpsAcquisition::get_right_block()
{
return acquisition_;
}
void GpsL2MPcpsAcquisition::set_resampler_latency(uint32_t latency_samples)
{
acquisition_->set_resampler_latency(latency_samples);
}
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