mirror of https://github.com/gnss-sdr/gnss-sdr
328 lines
11 KiB
C++
328 lines
11 KiB
C++
/*!
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* \file gps_l1_ca_gps_sdr_acquisition_cc.cc
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* \brief Brief description of the file here
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* \author Carlos Aviles, 2010. carlos.avilesr(at)googlemail.com
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* Luis Esteve, 2011. luis(at)epsilon-formacion.com
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*
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* Detailed description of the file here if needed.
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2011 (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_gps_sdr_acquisition_cc.h"
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#include "control_message_factory.h"
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#include "gps_sdr_x86.h"
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#include <gnuradio/gr_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 <iostream>
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using google::LogMessage;
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gps_l1_ca_gps_sdr_acquisition_cc_sptr gps_l1_ca_gps_sdr_make_acquisition_cc(
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unsigned int sampled_ms, long freq, long fs_in, int samples_per_ms,
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gr_msg_queue_sptr queue, bool dump, std::string dump_filename)
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{
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return gps_l1_ca_gps_sdr_acquisition_cc_sptr(
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new gps_l1_ca_gps_sdr_acquisition_cc(sampled_ms, freq, fs_in,
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samples_per_ms, queue, dump, dump_filename));
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}
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gps_l1_ca_gps_sdr_acquisition_cc::gps_l1_ca_gps_sdr_acquisition_cc(
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unsigned int sampled_ms, long freq, long fs_in, int samples_per_ms,
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gr_msg_queue_sptr queue, bool dump, std::string dump_filename) :
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gr_block("gps_l1_ca_gps_sdr_acquisition_cc", gr_make_io_signature(1, 1,
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sizeof(gr_complex) * samples_per_ms), gr_make_io_signature(0, 0,
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sizeof(gr_complex) * samples_per_ms))
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{
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// SAMPLE COUNTER
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d_sample_counter = 0;
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d_active = false;
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d_dump = dump;
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d_queue = queue;
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d_dump_filename = dump_filename;
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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_doppler_max = 0;
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d_satellite = 0;
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d_fft_size = d_sampled_ms * d_samples_per_ms;
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d_doppler_freq_phase = 0.0;
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d_prn_code_phase = 0;
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d_mag = 0;
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d_mean = 0.0;
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d_count = 0;
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d_sine_if = new gr_complex[d_fft_size];
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d_sine_250 = new gr_complex[d_fft_size];
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d_sine_500 = new gr_complex[d_fft_size];
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d_sine_750 = new gr_complex[d_fft_size];
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d_fft_codes = (gr_complex*)malloc(sizeof(gr_complex) * d_samples_per_ms);
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// Direct FFT
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d_fft_if = new gri_fft_complex(d_fft_size, true);
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d_fft_250 = new gri_fft_complex(d_fft_size, true);
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d_fft_500 = new gri_fft_complex(d_fft_size, true);
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d_fft_750 = new gri_fft_complex(d_fft_size, true);
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// Inverse FFT
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d_ifft = new gri_fft_complex(d_fft_size, false);
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d_best_magnitudes = new float[d_fft_size];
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sine_gen_complex(d_sine_if, -d_freq, d_fs_in, d_fft_size);
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sine_gen_complex(d_sine_250, -d_freq - 250, d_fs_in, d_fft_size);
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sine_gen_complex(d_sine_500, -d_freq - 500, d_fs_in, d_fft_size);
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sine_gen_complex(d_sine_750, -d_freq - 750, d_fs_in, d_fft_size);
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DLOG(INFO) << "fs in " << d_fs_in;
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DLOG(INFO) << "Doppler max " << d_doppler_max;
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DLOG(INFO) << "IF " << d_freq;
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DLOG(INFO) << "Satellite " << d_satellite;
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DLOG(INFO) << "Sampled_ms " << d_sampled_ms;
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DLOG(INFO) << "FFT_size " << d_fft_size;
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DLOG(INFO) << "dump filename " << d_dump_filename;
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DLOG(INFO) << "dump " << d_dump;
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}
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gps_l1_ca_gps_sdr_acquisition_cc::~gps_l1_ca_gps_sdr_acquisition_cc()
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{
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delete[] d_sine_if;
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delete[] d_sine_250;
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delete[] d_sine_500;
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delete[] d_sine_750;
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delete[] d_fft_codes;
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delete[] d_fft_if;
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delete[] d_fft_250;
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delete[] d_fft_500;
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delete[] d_fft_750;
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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 gps_l1_ca_gps_sdr_acquisition_cc::set_satellite(unsigned int satellite)
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{
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d_satellite = satellite;
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d_prn_code_phase = 0;
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d_doppler_freq_phase = 0;
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d_mag = 0;
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// Now the GPS codes are generated on the fly using a custom version of the GPS code generator
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code_gen_complex_sampled(d_fft_if->get_inbuf(), satellite, d_fs_in, 0);
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d_fft_if->execute(); // We need the FFT of GPS C/A code
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memcpy(d_fft_codes, d_fft_if->get_outbuf(), sizeof(gr_complex)
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* d_samples_per_ms);
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}
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signed int gps_l1_ca_gps_sdr_acquisition_cc::prn_code_phase()
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{
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return d_prn_code_phase;
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}
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int gps_l1_ca_gps_sdr_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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if (!d_active)
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{
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d_sample_counter += d_fft_size * noutput_items; // sample counter
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consume_each(noutput_items);
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return 0;
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}
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d_sample_counter += d_fft_size; // sample counter
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bool positive_acquisition = false;
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int acquisition_message = -1; //0=STOP_CHANNEL 1=ACQ_SUCCEES 2=ACQ_FAIL
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LOG_AT_LEVEL(INFO) << "Channel: " << d_channel
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<< " , doing acquisition of satellite: " << d_satellite
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<< " ,at sample stamp: " << d_sample_counter;
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const gr_complex *in = (const gr_complex *)input_items[0];
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//Perform the carrier wipe-off
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for (unsigned int j = 0; j < d_fft_size; j++)
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{
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d_fft_if->get_inbuf()[j] = in[j] * d_sine_if[j];
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d_fft_250->get_inbuf()[j] = in[j] * d_sine_250[j];
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d_fft_500->get_inbuf()[j] = in[j] * d_sine_500[j];
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d_fft_750->get_inbuf()[j] = in[j] * d_sine_750[j];
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}
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// Perform the FFT of the resulting signal
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d_fft_if->execute();
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d_fft_250->execute();
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d_fft_500->execute();
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d_fft_750->execute();
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//----------------------------------------------------------------------
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//---Calculate cross-correlation magnitudes using:
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//----> the circular convolution property of FFT:
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//----> the frequency-shift property of the FFT: y(t)=exp(jw0t)x(t) -> Y(w)=X(w-w0)
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for (int j = (int)-(d_doppler_max / 1000); j < (int)d_doppler_max / 1000; j++)
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{ // doppler search steps
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calculate_magnitudes(d_fft_if->get_outbuf(), j, 0);
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calculate_magnitudes(d_fft_250->get_outbuf(), j, 1);
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calculate_magnitudes(d_fft_500->get_outbuf(), j, 2);
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calculate_magnitudes(d_fft_750->get_outbuf(), j, 3);
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}
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if (d_dump)
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{
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std::stringstream ss;
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ss << "./data/acquisition_" << d_channel << "_" << d_satellite << "_"
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<< d_count << ".dat";
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d_dump_file.open(ss.str().c_str(), std::ios::out | std::ios::binary);
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std::streamsize n = sizeof(float) * (d_fft_size);
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d_dump_file.write((char*)d_best_magnitudes, n);
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d_dump_file.close();
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}
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if (d_test_statistics > d_threshold)
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{ //TODO: Include in configuration parameters and check value!!
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positive_acquisition = true;
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d_acq_sample_stamp = d_sample_counter;
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LOG_AT_LEVEL(INFO) << "POSITIVE ACQUISITION of channel " << d_channel;
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LOG_AT_LEVEL(INFO) << "Satellite " << d_satellite;
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LOG_AT_LEVEL(INFO) << "Code Phase " << d_prn_code_phase;
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LOG_AT_LEVEL(INFO) << "Doppler " << d_doppler_freq_phase;
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LOG_AT_LEVEL(INFO) << "Magnitude " << d_mag;
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LOG_AT_LEVEL(INFO) << "Mean " << d_mean;
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LOG_AT_LEVEL(INFO) << "Test statistics value " << d_test_statistics;
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LOG_AT_LEVEL(INFO) << "Test statistics threshold " << d_threshold;
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LOG_AT_LEVEL(INFO) << "Acq sample stamp " << d_acq_sample_stamp;
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}
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else
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{
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LOG_AT_LEVEL(INFO) << "NEGATIVE ACQUISITION of channel " << d_channel;
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LOG_AT_LEVEL(INFO) << "Satellite " << d_satellite;
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LOG_AT_LEVEL(INFO) << "Test statistics value " << d_test_statistics;
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LOG_AT_LEVEL(INFO) << "Test statistics threshold " << d_threshold;
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LOG_AT_LEVEL(INFO) << "Acq sample stamp " << d_acq_sample_stamp;
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}
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d_active = false;
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LOG_AT_LEVEL(INFO) << "d_count " << d_count;
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if (positive_acquisition)
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{
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acquisition_message = 1;
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}
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else
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{
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acquisition_message = 2;
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}
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d_channel_internal_queue->push(acquisition_message);
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return 0;
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}
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void gps_l1_ca_gps_sdr_acquisition_cc::calculate_magnitudes(
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gr_complex* fft_signal, int doppler_shift, int doppler_offset)
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{
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unsigned int indext = 0;
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float magt = 0.0;
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std::complex<float> tmp_cpx;
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// FFT frequency-shift property
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if (doppler_shift != 0)
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{
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for (unsigned int i = 0; i < d_fft_size; i++)
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{
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//complex conjugate (optimize me!)
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tmp_cpx = std::complex<float>(d_fft_codes[i].real(),
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-d_fft_codes[i].imag());
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d_ifft->get_inbuf()[i] = fft_signal[(doppler_shift + i
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+ d_fft_size) % d_fft_size] * tmp_cpx;
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}
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}
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else
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{
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for (unsigned int i = 0; i < d_fft_size; i++)
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{
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//complex conjugate (optimize me!)
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tmp_cpx = std::complex<float>(d_fft_codes[i].real(),
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-d_fft_codes[i].imag());
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d_ifft->get_inbuf()[i] = fft_signal[i] * tmp_cpx;
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}
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}
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d_ifft->execute(); // inverse FFT of the result = convolution in time
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x86_gr_complex_mag(d_ifft->get_outbuf(), d_fft_size); // d_ifft->get_outbuf()=|abs(·)|^2
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x86_float_max((float*)d_ifft->get_outbuf(), &indext, &magt, d_fft_size); // find max of |abs(<28>)|^2 -> index and magt
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if (magt > d_mag)
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{ // if the magnitude is > threshold
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// save the synchronization parameters
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d_mag = magt;
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d_prn_code_phase = indext;
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d_doppler_freq_phase = -((doppler_shift * 1000.0) + (doppler_offset
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* 250.0));
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// save the circular correlation of this Doppler shift
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memcpy(d_best_magnitudes, d_ifft->get_outbuf(), sizeof(float)
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* d_fft_size);
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// Remove the maximum and its neighbors to calculate the mean
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((float*)d_ifft->get_outbuf())[indext] = 0.0;
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if (indext != 0)
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{
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((float*)d_ifft->get_outbuf())[indext - 1] = 0.0;
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}
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if (indext != d_fft_size - 1)
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{
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((float*)d_ifft->get_outbuf())[indext + 1] = 0.0;
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}
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for (unsigned int i = 0; i < d_fft_size; i++)
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{
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d_mean += ((float*)d_ifft->get_outbuf())[i];
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}
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d_mean = d_mean / d_fft_size;
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d_test_statistics = d_mag / d_mean;
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}
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}
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