mirror of https://github.com/gnss-sdr/gnss-sdr
405 lines
15 KiB
C++
405 lines
15 KiB
C++
/*!
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* \file galileo_pcps_8ms_acquisition_cc.cc
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* \brief This class implements a Parallel Code Phase Search Acquisition for
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* Galileo E1 signals with coherent integration time = 8 ms (two codes)
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* \author Marc Molina, 2013. marc.molina.pena(at)gmail.com
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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 "galileo_pcps_8ms_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 <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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using google::LogMessage;
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galileo_pcps_8ms_acquisition_cc_sptr galileo_pcps_8ms_make_acquisition_cc(
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unsigned int sampled_ms, unsigned int max_dwells,
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unsigned int doppler_max, long freq, long fs_in,
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int samples_per_ms, int samples_per_code,
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gr::msg_queue::sptr queue, bool dump,
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std::string dump_filename)
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{
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return galileo_pcps_8ms_acquisition_cc_sptr(
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new galileo_pcps_8ms_acquisition_cc(sampled_ms, max_dwells, doppler_max, freq, fs_in, samples_per_ms,
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samples_per_code, queue, dump, dump_filename));
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}
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galileo_pcps_8ms_acquisition_cc::galileo_pcps_8ms_acquisition_cc(
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unsigned int sampled_ms, unsigned int max_dwells,
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unsigned int doppler_max, long freq, long fs_in,
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int samples_per_ms, int samples_per_code,
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gr::msg_queue::sptr queue, bool dump,
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std::string dump_filename) :
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gr::block("galileo_pcps_8ms_acquisition_cc",
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gr::io_signature::make(1, 1, sizeof(gr_complex) * sampled_ms * samples_per_ms),
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gr::io_signature::make(0, 0, sizeof(gr_complex) * sampled_ms * samples_per_ms))
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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_state = 0;
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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_samples_per_code = samples_per_code;
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d_sampled_ms = sampled_ms;
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d_max_dwells = max_dwells;
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d_well_count = 0;
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d_doppler_max = doppler_max;
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d_fft_size = d_sampled_ms * d_samples_per_ms;
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d_mag = 0;
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d_input_power = 0.0;
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d_num_doppler_bins = 0;
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//todo: do something if posix_memalign fails
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if (posix_memalign((void**)&d_fft_code_A, 16, d_fft_size * sizeof(gr_complex)) == 0){};
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if (posix_memalign((void**)&d_fft_code_B, 16, d_fft_size * sizeof(gr_complex)) == 0){};
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if (posix_memalign((void**)&d_magnitude, 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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galileo_pcps_8ms_acquisition_cc::~galileo_pcps_8ms_acquisition_cc()
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{
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for (unsigned int doppler_index = 0; doppler_index < d_num_doppler_bins; doppler_index++)
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{
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free(d_grid_doppler_wipeoffs[doppler_index]);
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}
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if (d_num_doppler_bins > 0)
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{
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delete[] d_grid_doppler_wipeoffs;
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}
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free(d_fft_code_A);
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free(d_fft_code_B);
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free(d_magnitude);
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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 galileo_pcps_8ms_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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d_fft_if->execute(); // We need the FFT of local code
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//Conjugate the local code
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if (is_unaligned())
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{
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volk_32fc_conjugate_32fc_u(d_fft_code_A,d_fft_if->get_outbuf(),d_fft_size);
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}
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else
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{
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volk_32fc_conjugate_32fc_a(d_fft_code_A,d_fft_if->get_outbuf(),d_fft_size);
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}
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volk_32fc_s32fc_multiply_32fc_a(&(d_fft_if->get_inbuf())[d_samples_per_code],
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&code[d_samples_per_code], gr_complex(-1,0),
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d_samples_per_code);
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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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if (is_unaligned())
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{
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volk_32fc_conjugate_32fc_u(d_fft_code_B,d_fft_if->get_outbuf(),d_fft_size);
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}
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else
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{
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volk_32fc_conjugate_32fc_a(d_fft_code_B,d_fft_if->get_outbuf(),d_fft_size);
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}
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}
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void galileo_pcps_8ms_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_mag = 0.0;
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d_input_power = 0.0;
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// Create the carrier Doppler wipeoff signals
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d_num_doppler_bins = 0;//floor(2*std::abs((int)d_doppler_max)/d_doppler_step);
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for (int doppler = (int)(-d_doppler_max); doppler <= (int)d_doppler_max; doppler += d_doppler_step)
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{
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d_num_doppler_bins++;
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}
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d_grid_doppler_wipeoffs = new gr_complex*[d_num_doppler_bins];
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for (unsigned int doppler_index=0;doppler_index<d_num_doppler_bins;doppler_index++)
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{
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if (posix_memalign((void**)&(d_grid_doppler_wipeoffs[doppler_index]), 16,
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d_fft_size * sizeof(gr_complex)) == 0){};
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int doppler=-(int)d_doppler_max+d_doppler_step*doppler_index;
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complex_exp_gen_conj(d_grid_doppler_wipeoffs[doppler_index],
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d_freq + doppler, d_fs_in, d_fft_size);
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}
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}
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int galileo_pcps_8ms_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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int acquisition_message = -1; //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL
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switch (d_state)
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{
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case 0:
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{
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if (d_active)
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{
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//restart acquisition variables
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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_well_count = 0;
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d_mag = 0.0;
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d_input_power = 0.0;
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d_test_statistics = 0.0;
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d_state = 1;
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}
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d_sample_counter += d_fft_size * ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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break;
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}
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case 1:
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{
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// initialize acquisition algorithm
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int doppler;
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unsigned int indext = 0;
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unsigned int indext_A = 0;
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unsigned int indext_B = 0;
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float magt = 0.0;
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float magt_A = 0.0;
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float magt_B = 0.0;
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const gr_complex *in = (const gr_complex *)input_items[0]; //Get the input samples pointer
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float fft_normalization_factor = (float)d_fft_size * (float)d_fft_size;
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d_input_power = 0.0;
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d_mag = 0.0;
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d_sample_counter += d_fft_size; // sample counter
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d_well_count++;
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DLOG(INFO) << "Channel: " << d_channel
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<< " , doing acquisition of satellite: " << d_gnss_synchro->System << " "<< 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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// 1- Compute the input signal power estimation
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volk_32fc_magnitude_squared_32f_a(d_magnitude, in, d_fft_size);
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volk_32f_accumulator_s32f_a(&d_input_power, d_magnitude, d_fft_size);
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d_input_power /= (float)d_fft_size;
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// 2- Doppler frequency search loop
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for (unsigned int doppler_index=0;doppler_index<d_num_doppler_bins;doppler_index++)
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{
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// doppler search steps
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doppler=-(int)d_doppler_max+d_doppler_step*doppler_index;
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volk_32fc_x2_multiply_32fc_a(d_fft_if->get_inbuf(), in,
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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(),
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d_fft_if->get_outbuf(), d_fft_code_A, d_fft_size);
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// compute the inverse FFT
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d_ifft->execute();
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// Search maximum
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volk_32fc_magnitude_squared_32f_a(d_magnitude, d_ifft->get_outbuf(), d_fft_size);
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volk_32f_index_max_16u_a(&indext_A, d_magnitude, d_fft_size);
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// Normalize the maximum value to correct the scale factor introduced by FFTW
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magt_A = d_magnitude[indext_A] / (fft_normalization_factor * fft_normalization_factor);
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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(),
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d_fft_if->get_outbuf(), d_fft_code_B, d_fft_size);
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// compute the inverse FFT
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d_ifft->execute();
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// Search maximum
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volk_32fc_magnitude_squared_32f_a(d_magnitude, d_ifft->get_outbuf(), d_fft_size);
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volk_32f_index_max_16u_a(&indext_B, d_magnitude, d_fft_size);
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// Normalize the maximum value to correct the scale factor introduced by FFTW
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magt_B = d_magnitude[indext_B] / (fft_normalization_factor * fft_normalization_factor);
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if (magt_A >= magt_B)
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{
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magt = magt_A;
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indext = indext_A;
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}
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else
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{
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magt = magt_B;
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indext = indext_B;
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}
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// 4- record the maximum peak and the associated synchronization parameters
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if (d_mag < magt)
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{
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d_mag = magt;
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d_gnss_synchro->Acq_delay_samples = (double)(indext % d_samples_per_code);
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d_gnss_synchro->Acq_doppler_hz = (double)doppler;
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d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
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}
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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_" << doppler << ".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_ifft->get_outbuf(), 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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}
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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 * d_mag / d_input_power;
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d_test_statistics = d_mag / d_input_power;
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if (d_test_statistics > d_threshold)
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{
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d_state = 2; // Positive acquisition
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}
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else
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{
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if (d_well_count == d_max_dwells)
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{
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d_state = 3; // Negative acquisition
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}
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}
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consume_each(1);
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break;
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}
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case 2:
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{
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// 6.1- Declare positive acquisition using a message queue
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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) << "magnitude " << d_mag;
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DLOG(INFO) << "input signal power " << d_input_power;
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d_active = false;
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d_state = 0;
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d_sample_counter += d_fft_size * ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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acquisition_message = 1;
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d_channel_internal_queue->push(acquisition_message);
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break;
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}
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case 3:
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{
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// 6.2- Declare negative acquisition using a message queue
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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;
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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) << "magnitude " << d_mag;
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DLOG(INFO) << "input signal power " << d_input_power;
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d_active = false;
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d_state = 0;
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d_sample_counter += d_fft_size * ninput_items[0]; // sample counter
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consume_each(ninput_items[0]);
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acquisition_message = 2;
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d_channel_internal_queue->push(acquisition_message);
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break;
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}
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}
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return 0;
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}
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