mirror of https://github.com/gnss-sdr/gnss-sdr
457 lines
17 KiB
C++
457 lines
17 KiB
C++
/*!
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* \file pcps_assisted_acquisition_cc.cc
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* \brief This class implements a Parallel Code Phase Search Acquisition with assistance and multi-dwells
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* \authors <ul>
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* <li> Javier Arribas, 2013. 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) 2010-2012 (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 "pcps_assisted_acquisition_cc.h"
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#include "gnss_signal_processing.h"
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#include "control_message_factory.h"
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#include "gps_acq_assist.h"
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#include <gnuradio/io_signature.h>
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#include <sstream>
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#include <glog/log_severity.h>
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#include <glog/logging.h>
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#include <volk/volk.h>
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#include "nco_lib.h"
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#include "concurrent_map.h"
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extern concurrent_map<Gps_Acq_Assist> global_gps_acq_assist_map;
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using google::LogMessage;
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pcps_assisted_acquisition_cc_sptr pcps_make_assisted_acquisition_cc(
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int max_dwells, unsigned int sampled_ms, int doppler_max, int doppler_min, long freq,
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long fs_in, int samples_per_ms, boost::shared_ptr<gr::msg_queue> queue, bool dump,
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std::string dump_filename)
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{
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return pcps_assisted_acquisition_cc_sptr(
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new pcps_assisted_acquisition_cc(max_dwells, sampled_ms, doppler_max, doppler_min, freq,
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fs_in, samples_per_ms, queue, dump, dump_filename));
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}
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pcps_assisted_acquisition_cc::pcps_assisted_acquisition_cc(
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int max_dwells, unsigned int sampled_ms, int doppler_max, int doppler_min, long freq,
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long fs_in, int samples_per_ms, boost::shared_ptr<gr::msg_queue> queue, bool dump,
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std::string dump_filename) :
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gr::block("pcps_assisted_acquisition_cc",
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gr::io_signature::make(1, 1, sizeof(gr_complex)),
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gr::io_signature::make(0, 0, sizeof(gr_complex)))
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{
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d_sample_counter = 0; // SAMPLE COUNTER
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d_active = false;
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d_queue = queue;
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d_freq = freq;
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d_fs_in = fs_in;
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d_samples_per_ms = samples_per_ms;
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d_sampled_ms = sampled_ms;
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d_config_doppler_max = doppler_max;
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d_config_doppler_min=doppler_min;
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d_fft_size = d_sampled_ms * d_samples_per_ms;
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// HS Acquisition
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d_max_dwells = max_dwells;
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d_gnuradio_forecast_samples = d_fft_size*4;
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d_input_power = 0.0;
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d_state = 0;
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d_disable_assist = false;
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//todo: do something if posix_memalign fails
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if (posix_memalign((void**)&d_carrier, 16, d_fft_size * sizeof(gr_complex)) == 0){};
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if (posix_memalign((void**)&d_fft_codes, 16, d_fft_size * sizeof(gr_complex)) == 0){};
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// Direct FFT
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d_fft_if = new gr::fft::fft_complex(d_fft_size, true);
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// Inverse FFT
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d_ifft = new gr::fft::fft_complex(d_fft_size, false);
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// For dumping samples into a file
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d_dump = dump;
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d_dump_filename = dump_filename;
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}
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void pcps_assisted_acquisition_cc::set_doppler_step(unsigned int doppler_step)
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{
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d_doppler_step = doppler_step;
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}
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void pcps_assisted_acquisition_cc::free_grid_memory()
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{
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for (int i=0;i<d_num_doppler_points;i++)
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{
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delete[] d_grid_data[i];
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delete[] d_grid_doppler_wipeoffs[i];
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}
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delete d_grid_data;
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}
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pcps_assisted_acquisition_cc::~pcps_assisted_acquisition_cc()
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{
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free(d_carrier);
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free(d_fft_codes);
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delete d_ifft;
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delete d_fft_if;
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if (d_dump)
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{
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d_dump_file.close();
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}
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}
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void pcps_assisted_acquisition_cc::set_local_code(std::complex<float> * code)
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{
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memcpy(d_fft_if->get_inbuf(), code, sizeof(gr_complex)*d_fft_size);
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}
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void pcps_assisted_acquisition_cc::init()
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{
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d_gnss_synchro->Acq_delay_samples = 0.0;
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d_gnss_synchro->Acq_doppler_hz = 0.0;
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d_gnss_synchro->Acq_samplestamp_samples = 0;
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d_input_power = 0.0;
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d_state = 0;
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d_fft_if->execute(); // We need the FFT of local code
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//Conjugate the local code
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volk_32fc_conjugate_32fc_a(d_fft_codes, d_fft_if->get_outbuf(), d_fft_size);
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}
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void pcps_assisted_acquisition_cc::forecast (int noutput_items,
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gr_vector_int &ninput_items_required)
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{
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ninput_items_required[0] = d_gnuradio_forecast_samples ; //set the required available samples in each call
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}
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void pcps_assisted_acquisition_cc::get_assistance()
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{
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Gps_Acq_Assist gps_acq_assisistance;
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if (global_gps_acq_assist_map.read(this->d_gnss_synchro->PRN, gps_acq_assisistance)==true)
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{
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//TODO: use the LO tolerance here
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if (gps_acq_assisistance.dopplerUncertainty >= 1000)
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{
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d_doppler_max = gps_acq_assisistance.d_Doppler0 + gps_acq_assisistance.dopplerUncertainty*2;
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d_doppler_min = gps_acq_assisistance.d_Doppler0 - gps_acq_assisistance.dopplerUncertainty*2;
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}
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else
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{
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d_doppler_max = gps_acq_assisistance.d_Doppler0 + 1000;
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d_doppler_min = gps_acq_assisistance.d_Doppler0 - 1000;
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}
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this->d_disable_assist = false;
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std::cout << "Acq assist ENABLED for GPS SV "<< this->d_gnss_synchro->PRN <<" (Doppler max,Doppler min)=("
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<< d_doppler_max << "," << d_doppler_min << ")" << std::endl;
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}
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else
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{
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this->d_disable_assist = true;
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std::cout << "Acq assist DISABLED for GPS SV "<< this->d_gnss_synchro->PRN << std::endl;
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}
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}
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void pcps_assisted_acquisition_cc::reset_grid()
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{
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d_well_count = 0;
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for (int i=0;i<d_num_doppler_points;i++)
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{
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for (unsigned int j=0;j<d_fft_size;j++)
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{
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d_grid_data[i][j] = 0.0;
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}
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}
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}
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void pcps_assisted_acquisition_cc::redefine_grid()
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{
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if (this->d_disable_assist==true)
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{
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d_doppler_max = d_config_doppler_max;
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d_doppler_min = d_config_doppler_min;
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}
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// Create the search grid array
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d_num_doppler_points = floor(std::abs(d_doppler_max-d_doppler_min)/d_doppler_step);
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d_grid_data=new float*[d_num_doppler_points];
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for (int i=0; i<d_num_doppler_points; i++)
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{
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d_grid_data[i] = new float[d_fft_size];
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}
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// create the carrier Doppler wipeoff signals
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int doppler_hz;
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float phase_step_rad;
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d_grid_doppler_wipeoffs = new gr_complex*[d_num_doppler_points];
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for (int doppler_index=0; doppler_index<d_num_doppler_points; doppler_index++)
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{
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doppler_hz = d_doppler_min+d_doppler_step*doppler_index;
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// doppler search steps
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// compute the carrier doppler wipe-off signal and store it
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phase_step_rad = (float)GPS_TWO_PI*doppler_hz / (float)d_fs_in;
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d_grid_doppler_wipeoffs[doppler_index] = new gr_complex[d_fft_size];
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fxp_nco(d_grid_doppler_wipeoffs[doppler_index], d_fft_size,0, phase_step_rad);
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}
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}
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double pcps_assisted_acquisition_cc::search_maximum()
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{
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float magt = 0.0;
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float fft_normalization_factor;
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int index_doppler = 0;
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unsigned int tmp_intex_t;
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unsigned int index_time = 0;
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for (int i=0;i<d_num_doppler_points;i++)
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{
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volk_32f_index_max_16u_a(&tmp_intex_t,d_grid_data[i],d_fft_size);
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if (d_grid_data[i][tmp_intex_t] > magt)
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{
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magt = d_grid_data[i][index_time];
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index_doppler = i;
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index_time = tmp_intex_t;
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}
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}
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// Normalize the maximum value to correct the scale factor introduced by FFTW
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fft_normalization_factor = (float)d_fft_size * (float)d_fft_size;
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magt = magt / (fft_normalization_factor * fft_normalization_factor);
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// 5- Compute the test statistics and compare to the threshold
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d_test_statistics = 2 * d_fft_size * magt /(d_input_power*d_well_count);
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// 4- record the maximum peak and the associated synchronization parameters
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d_gnss_synchro->Acq_delay_samples = (double)index_time;
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d_gnss_synchro->Acq_doppler_hz = (double)(index_doppler*d_doppler_step + d_doppler_min);
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d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
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// Record results to file if required
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if (d_dump)
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{
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std::stringstream filename;
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std::streamsize n = 2 * sizeof(float) * (d_fft_size); // complex file write
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filename.str("");
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filename << "../data/test_statistics_" << d_gnss_synchro->System
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<< "_" << d_gnss_synchro->Signal << "_sat_"
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<< d_gnss_synchro->PRN << "_doppler_" << d_gnss_synchro->Acq_doppler_hz << ".dat";
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d_dump_file.open(filename.str().c_str(), std::ios::out | std::ios::binary);
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d_dump_file.write((char*)d_grid_data[index_doppler], n); //write directly |abs(x)|^2 in this Doppler bin?
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d_dump_file.close();
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}
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return d_test_statistics;
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}
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float pcps_assisted_acquisition_cc::estimate_input_power(gr_vector_const_void_star &input_items)
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{
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const gr_complex *in = (const gr_complex *)input_items[0]; //Get the input samples pointer
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// 1- Compute the input signal power estimation
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float* p_tmp_vector;
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if (posix_memalign((void**)&p_tmp_vector, 16, d_fft_size * sizeof(float)) == 0){};
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volk_32fc_magnitude_squared_32f_u(p_tmp_vector, in, d_fft_size);
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const float* p_const_tmp_vector = p_tmp_vector;
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float power;
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volk_32f_accumulator_s32f_a(&power, p_const_tmp_vector, d_fft_size);
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free(p_tmp_vector);
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return ( power / (float)d_fft_size);
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}
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int pcps_assisted_acquisition_cc::compute_and_accumulate_grid(gr_vector_const_void_star &input_items)
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{
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// initialize acquisition algorithm
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const gr_complex *in = (const gr_complex *)input_items[0]; //Get the input samples pointer
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DLOG(INFO) << "Channel: " << d_channel
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<< " , doing acquisition of satellite: " << d_gnss_synchro->System << " "
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<< d_gnss_synchro->PRN
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<< " ,sample stamp: " << d_sample_counter << ", threshold: "
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<< d_threshold << ", doppler_max: " << d_doppler_max
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<< ", doppler_step: " << d_doppler_step;
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// 2- Doppler frequency search loop
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float* p_tmp_vector;
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if (posix_memalign((void**)&p_tmp_vector, 16, d_fft_size * sizeof(float)) == 0){};
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for (int doppler_index=0; doppler_index<d_num_doppler_points; doppler_index++)
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{
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// doppler search steps
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// Perform the carrier wipe-off
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volk_32fc_x2_multiply_32fc_u(d_fft_if->get_inbuf(), in, d_grid_doppler_wipeoffs[doppler_index], d_fft_size);
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// 3- Perform the FFT-based convolution (parallel time search)
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// Compute the FFT of the carrier wiped--off incoming signal
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d_fft_if->execute();
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// Multiply carrier wiped--off, Fourier transformed incoming signal
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// with the local FFT'd code reference using SIMD operations with VOLK library
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volk_32fc_x2_multiply_32fc_a(d_ifft->get_inbuf(), d_fft_if->get_outbuf(), d_fft_codes, d_fft_size);
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// compute the inverse FFT
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d_ifft->execute();
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// save the grid matrix delay file
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volk_32fc_magnitude_squared_32f_a(p_tmp_vector, d_ifft->get_outbuf(), d_fft_size);
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const float* old_vector = d_grid_data[doppler_index];
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volk_32f_x2_add_32f_a(d_grid_data[doppler_index], old_vector, p_tmp_vector, d_fft_size);
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}
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free(p_tmp_vector);
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return d_fft_size;
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}
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int pcps_assisted_acquisition_cc::general_work(int noutput_items,
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gr_vector_int &ninput_items, gr_vector_const_void_star &input_items,
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gr_vector_void_star &output_items)
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{
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/*!
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* TODO: High sensitivity acquisition algorithm:
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* State Mechine:
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* S0. StandBy. If d_active==1 -> S1
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* S1. GetAssist. Define search grid with assistance information. Reset grid matrix -> S2
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* S2. ComputeGrid. Perform the FFT acqusition doppler and delay grid.
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* Accumulate the search grid matrix (#doppler_bins x #fft_size)
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* Compare maximum to threshold and decide positive or negative
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* If T>=gamma -> S4 else
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* If d_well_count<max_dwells -> S2
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* else if !disable_assist -> S3
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* else -> S5.
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* S3. RedefineGrid. Open the grid search to unasisted acquisition. Reset counters and grid. -> S2
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* S4. Positive_Acq: Send message and stop acq -> S0
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* S5. Negative_Acq: Send message and stop acq -> S0
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*/
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switch (d_state)
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{
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case 0: // S0. StandBy
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if (d_active==true) d_state = 1;
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d_sample_counter += ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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break;
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case 1: // S1. GetAssist
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get_assistance();
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redefine_grid();
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reset_grid();
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d_sample_counter += ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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d_state = 2;
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break;
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case 2: // S2. ComputeGrid
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int consumed_samples;
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consumed_samples = compute_and_accumulate_grid(input_items);
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d_well_count++;
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if (d_well_count>=d_max_dwells)
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{
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d_state=3;
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}
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d_sample_counter += consumed_samples;
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consume_each(consumed_samples);
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break;
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case 3: // Compute test statistics and decide
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d_input_power = estimate_input_power(input_items);
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d_test_statistics = search_maximum();
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if (d_test_statistics > d_threshold)
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{
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d_state = 5;
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}
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else
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{
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if (d_disable_assist == false)
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{
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d_disable_assist = true;
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std::cout << "Acq assist DISABLED for GPS SV "<< this->d_gnss_synchro->PRN << std::endl;
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d_state = 4;
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}
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else
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{
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d_state = 6;
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}
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}
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d_sample_counter += ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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break;
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case 4: // RedefineGrid
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free_grid_memory();
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redefine_grid();
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reset_grid();
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d_sample_counter += ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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d_state = 2;
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break;
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case 5: // Positive_Acq
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DLOG(INFO) << "positive acquisition";
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DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
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DLOG(INFO) << "sample_stamp " << d_sample_counter;
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DLOG(INFO) << "test statistics value " << d_test_statistics;
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DLOG(INFO) << "test statistics threshold " << d_threshold;
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DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
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DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
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DLOG(INFO) << "input signal power " << d_input_power;
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d_active = false;
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// Send message to channel queue //0=STOP_CHANNEL 1=ACQ_SUCCESS 2=ACQ_FAIL
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d_channel_internal_queue->push(1); // 1-> positive acquisition
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free_grid_memory();
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// consume samples to not block the GNU Radio flowgraph
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d_sample_counter += ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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d_state = 0;
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break;
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case 6: // Negative_Acq
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DLOG(INFO) << "negative acquisition";
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DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
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DLOG(INFO) << "sample_stamp " << d_sample_counter;
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|
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;
|
|
DLOG(INFO) << "input signal power " << d_input_power;
|
|
|
|
d_active = false;
|
|
// Send message to channel queue //0=STOP_CHANNEL 1=ACQ_SUCCESS 2=ACQ_FAIL
|
|
d_channel_internal_queue->push(2); // 2-> negative acquisition
|
|
free_grid_memory();
|
|
// consume samples to not block the GNU Radio flowgraph
|
|
d_sample_counter += ninput_items[0]; // sample counter
|
|
consume_each(ninput_items[0]);
|
|
d_state = 0;
|
|
break;
|
|
default:
|
|
d_state = 0;
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|