mirror of https://github.com/gnss-sdr/gnss-sdr
258 lines
7.9 KiB
C++
258 lines
7.9 KiB
C++
/*!
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* \file gps_l1_ca_pcps_acquisition_fpga.cc
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* \brief Adapts a PCPS acquisition block to an FPGA Acquisition Interface for
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* GPS L1 C/A signals. This file is based on the file gps_l1_ca_pcps_acquisition.cc
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* \authors <ul>
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* <li> Marc Majoral, 2017. mmajoral(at)cttc.cat
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* </ul>
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2017 (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 <http://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#include "gps_l1_ca_pcps_acquisition_fpga.h"
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#include <stdexcept>
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#include <boost/math/distributions/exponential.hpp>
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#include <glog/logging.h>
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#include "GPS_L1_CA.h"
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#include "configuration_interface.h"
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#include "gnss_sdr_flags.h"
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using google::LogMessage;
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GpsL1CaPcpsAcquisitionFpga::GpsL1CaPcpsAcquisitionFpga(
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ConfigurationInterface* configuration, std::string role,
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unsigned int in_streams, unsigned int out_streams) : role_(role), in_streams_(in_streams), out_streams_(out_streams)
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{
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unsigned int code_length;
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bool bit_transition_flag;
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bool use_CFAR_algorithm_flag;
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unsigned int sampled_ms;
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long fs_in;
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long ifreq;
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bool dump;
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std::string dump_filename;
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unsigned int nsamples_total;
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unsigned int select_queue_Fpga;
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std::string device_name;
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configuration_ = configuration;
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std::string default_item_type = "cshort";
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std::string default_dump_filename = "./data/acquisition.dat";
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DLOG(INFO) << "role " << role;
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item_type_ = configuration_->property(role + ".item_type", default_item_type);
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long 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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ifreq = configuration_->property(role + ".if", 0);
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dump = configuration_->property(role + ".dump", false);
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doppler_max_ = configuration_->property(role + ".doppler_max", 5000);
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if (FLAGS_doppler_max != 0) doppler_max_ = FLAGS_doppler_max;
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sampled_ms = configuration_->property(role + ".coherent_integration_time_ms", 1);
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// note : the FPGA is implemented according to bit transition flag = 0. Setting bit transition flag to 1 has no effect.
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bit_transition_flag = configuration_->property(role + ".bit_transition_flag", false);
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// note : the FPGA is implemented according to use_CFAR_algorithm = 0. Setting use_CFAR_algorithm to 1 has no effect.
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use_CFAR_algorithm_flag = configuration_->property(role + ".use_CFAR_algorithm", false);
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// note : the FPGA does not use the max_dwells variable.
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max_dwells_ = configuration_->property(role + ".max_dwells", 1);
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dump_filename = configuration_->property(role + ".dump_filename", default_dump_filename);
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//--- Find number of samples per spreading code -------------------------
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code_length = round(
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fs_in / (GPS_L1_CA_CODE_RATE_HZ / GPS_L1_CA_CODE_LENGTH_CHIPS));
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// code length has the same value as d_fft_size
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float nbits;
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nbits = ceilf(log2f(code_length));
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nsamples_total = pow(2, nbits);
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//vector_length_ = code_length_ * sampled_ms_;
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vector_length_ = nsamples_total * sampled_ms;
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// if( bit_transition_flag_ )
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// {
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// vector_length_ *= 2;
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// }
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select_queue_Fpga = configuration_->property(role + ".select_queue_Fpga", 0);
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std::string default_device_name = "/dev/uio0";
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device_name = configuration_->property(role + ".devicename", default_device_name);
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if (item_type_.compare("cshort") == 0)
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{
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item_size_ = sizeof(lv_16sc_t);
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gps_acquisition_fpga_sc_ = gps_pcps_make_acquisition_fpga_sc(
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sampled_ms, max_dwells_, doppler_max_, ifreq, fs_in,
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code_length, code_length, vector_length_, nsamples_total,
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bit_transition_flag, use_CFAR_algorithm_flag,
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select_queue_Fpga, device_name, dump, dump_filename);
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DLOG(INFO) << "acquisition("
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<< gps_acquisition_fpga_sc_->unique_id() << ")";
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}
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else
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{
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LOG(WARNING) << "item_type configured to " << item_type_ << "but FPGA implementation only accepts cshort";
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throw std::invalid_argument("Wrong input_type configuration. Should be cshort");
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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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gnss_synchro_ = 0;
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}
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GpsL1CaPcpsAcquisitionFpga::~GpsL1CaPcpsAcquisitionFpga()
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{
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}
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void GpsL1CaPcpsAcquisitionFpga::set_channel(unsigned int channel)
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{
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channel_ = channel;
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gps_acquisition_fpga_sc_->set_channel(channel_);
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}
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void GpsL1CaPcpsAcquisitionFpga::set_threshold(float threshold)
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{
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float pfa = configuration_->property(role_ + ".pfa", 0.0);
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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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gps_acquisition_fpga_sc_->set_threshold(threshold_);
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}
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void GpsL1CaPcpsAcquisitionFpga::set_doppler_max(unsigned int doppler_max)
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{
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doppler_max_ = doppler_max;
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gps_acquisition_fpga_sc_->set_doppler_max(doppler_max_);
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}
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void GpsL1CaPcpsAcquisitionFpga::set_doppler_step(unsigned int doppler_step)
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{
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doppler_step_ = doppler_step;
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gps_acquisition_fpga_sc_->set_doppler_step(doppler_step_);
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}
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void GpsL1CaPcpsAcquisitionFpga::set_gnss_synchro(Gnss_Synchro* gnss_synchro)
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{
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gnss_synchro_ = gnss_synchro;
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gps_acquisition_fpga_sc_->set_gnss_synchro(gnss_synchro_);
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}
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signed int GpsL1CaPcpsAcquisitionFpga::mag()
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{
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return gps_acquisition_fpga_sc_->mag();
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}
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void GpsL1CaPcpsAcquisitionFpga::init()
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{
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gps_acquisition_fpga_sc_->init();
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set_local_code();
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}
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void GpsL1CaPcpsAcquisitionFpga::set_local_code()
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{
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gps_acquisition_fpga_sc_->set_local_code();
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}
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void GpsL1CaPcpsAcquisitionFpga::reset()
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{
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gps_acquisition_fpga_sc_->set_active(true);
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}
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void GpsL1CaPcpsAcquisitionFpga::set_state(int state)
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{
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gps_acquisition_fpga_sc_->set_state(state);
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}
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float GpsL1CaPcpsAcquisitionFpga::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_);
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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 / static_cast<double>(ncells);
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double val = pow(1.0 - pfa, exponent);
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double lambda = double(vector_length_);
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boost::math::exponential_distribution<double> mydist(lambda);
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float threshold = static_cast<float>(quantile(mydist, val));
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return threshold;
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}
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void GpsL1CaPcpsAcquisitionFpga::connect(gr::top_block_sptr top_block)
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{
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//nothing to connect
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}
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void GpsL1CaPcpsAcquisitionFpga::disconnect(gr::top_block_sptr top_block)
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{
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//nothing to disconnect
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}
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gr::basic_block_sptr GpsL1CaPcpsAcquisitionFpga::get_left_block()
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{
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return gps_acquisition_fpga_sc_;
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}
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gr::basic_block_sptr GpsL1CaPcpsAcquisitionFpga::get_right_block()
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{
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return gps_acquisition_fpga_sc_;
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}
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