mirror of https://github.com/gnss-sdr/gnss-sdr
450 lines
19 KiB
C++
450 lines
19 KiB
C++
/*!
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* \file glonass_l2_ca_telemetry_decoder_cc.cc
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* \brief Implementation of an adapter of a GLONASS L1 C/A NAV data decoder block
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* to a TelemetryDecoderInterface
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* \author Damian Miralles, 2018. dmiralles2009(at)gmail.com
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2015 (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 "glonass_l2_ca_telemetry_decoder_cc.h"
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#include <boost/lexical_cast.hpp>
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#include <gnuradio/io_signature.h>
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#include <glog/logging.h>
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#define CRC_ERROR_LIMIT 6
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using google::LogMessage;
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glonass_l2_ca_telemetry_decoder_cc_sptr
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glonass_l2_ca_make_telemetry_decoder_cc(const Gnss_Satellite &satellite, bool dump)
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{
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return glonass_l2_ca_telemetry_decoder_cc_sptr(new glonass_l2_ca_telemetry_decoder_cc(satellite, dump));
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}
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glonass_l2_ca_telemetry_decoder_cc::glonass_l2_ca_telemetry_decoder_cc(
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const Gnss_Satellite &satellite,
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bool dump) : gr::block("glonass_l2_ca_telemetry_decoder_cc", gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)),
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gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)))
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{
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// Telemetry Bit transition synchronization port out
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this->message_port_register_out(pmt::mp("preamble_timestamp_s"));
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// Ephemeris data port out
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this->message_port_register_out(pmt::mp("telemetry"));
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// initialize internal vars
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d_dump = dump;
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d_satellite = Gnss_Satellite(satellite.get_system(), satellite.get_PRN());
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LOG(INFO) << "Initializing GLONASS L2 CA TELEMETRY DECODING";
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// Define the number of sampes per symbol. Notice that GLONASS has 2 rates,
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//one for the navigation data and the other for the preamble information
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d_samples_per_symbol = (GLONASS_L2_CA_CODE_RATE_HZ / GLONASS_L2_CA_CODE_LENGTH_CHIPS) / GLONASS_L2_CA_SYMBOL_RATE_BPS;
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// Set the preamble information
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unsigned short int preambles_bits[GLONASS_GNAV_PREAMBLE_LENGTH_BITS] = GLONASS_GNAV_PREAMBLE;
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// Since preamble rate is different than navigation data rate we use a constant
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d_symbols_per_preamble = GLONASS_GNAV_PREAMBLE_LENGTH_SYMBOLS;
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memcpy(static_cast<unsigned short int *>(this->d_preambles_bits), static_cast<unsigned short int *>(preambles_bits), GLONASS_GNAV_PREAMBLE_LENGTH_BITS * sizeof(unsigned short int));
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// preamble bits to sampled symbols
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d_preambles_symbols = static_cast<signed int *>(malloc(sizeof(signed int) * d_symbols_per_preamble));
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int n = 0;
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for (int i = 0; i < GLONASS_GNAV_PREAMBLE_LENGTH_BITS; i++)
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{
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for (unsigned int j = 0; j < GLONASS_GNAV_TELEMETRY_SYMBOLS_PER_PREAMBLE_BIT; j++)
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{
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if (d_preambles_bits[i] == 1)
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{
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d_preambles_symbols[n] = 1;
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}
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else
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{
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d_preambles_symbols[n] = -1;
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}
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n++;
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}
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}
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d_sample_counter = 0;
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d_stat = 0;
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d_preamble_index = 0;
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d_flag_frame_sync = false;
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d_flag_parity = false;
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d_TOW_at_current_symbol = 0;
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Flag_valid_word = false;
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delta_t = 0;
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d_CRC_error_counter = 0;
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d_flag_preamble = false;
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d_channel = 0;
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flag_TOW_set = false;
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d_preamble_time_samples = 0;
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}
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glonass_l2_ca_telemetry_decoder_cc::~glonass_l2_ca_telemetry_decoder_cc()
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{
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delete d_preambles_symbols;
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if (d_dump_file.is_open() == true)
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{
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try
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{
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d_dump_file.close();
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}
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catch (const std::exception &ex)
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{
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LOG(WARNING) << "Exception in destructor closing the dump file " << ex.what();
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}
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}
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}
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void glonass_l2_ca_telemetry_decoder_cc::decode_string(double *frame_symbols, int frame_length)
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{
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double chip_acc = 0.0;
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int chip_acc_counter = 0;
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// 1. Transform from symbols to bits
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std::string bi_binary_code;
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std::string relative_code;
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std::string data_bits;
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// Group samples into bi-binary code
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for (int i = 0; i < (frame_length); i++)
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{
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chip_acc += frame_symbols[i];
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chip_acc_counter += 1;
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if (chip_acc_counter == (GLONASS_GNAV_TELEMETRY_SYMBOLS_PER_BIT))
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{
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if (chip_acc > 0)
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{
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bi_binary_code.push_back('1');
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chip_acc_counter = 0;
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chip_acc = 0;
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}
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else
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{
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bi_binary_code.push_back('0');
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chip_acc_counter = 0;
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chip_acc = 0;
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}
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}
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}
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// Convert from bi-binary code to relative code
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for (int i = 0; i < (GLONASS_GNAV_STRING_BITS); i++)
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{
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if (bi_binary_code[2 * i] == '1' && bi_binary_code[2 * i + 1] == '0')
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{
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relative_code.push_back('1');
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}
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else
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{
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relative_code.push_back('0');
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}
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}
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// Convert from relative code to data bits
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data_bits.push_back('0');
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for (int i = 1; i < (GLONASS_GNAV_STRING_BITS); i++)
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{
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data_bits.push_back(((relative_code[i - 1] - '0') ^ (relative_code[i] - '0')) + '0');
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}
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// 2. Call the GLONASS GNAV string decoder
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d_nav.string_decoder(data_bits);
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// 3. Check operation executed correctly
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if (d_nav.flag_CRC_test == true)
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{
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LOG(INFO) << "GLONASS GNAV CRC correct on channel " << d_channel << " from satellite " << d_satellite;
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}
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else
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{
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LOG(INFO) << "GLONASS GNAV CRC error on channel " << d_channel << " from satellite " << d_satellite;
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}
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// 4. Push the new navigation data to the queues
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if (d_nav.have_new_ephemeris() == true)
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{
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// get object for this SV (mandatory)
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d_nav.gnav_ephemeris.i_satellite_freq_channel = d_satellite.get_rf_link();
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std::shared_ptr<Glonass_Gnav_Ephemeris> tmp_obj = std::make_shared<Glonass_Gnav_Ephemeris>(d_nav.get_ephemeris());
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this->message_port_pub(pmt::mp("telemetry"), pmt::make_any(tmp_obj));
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LOG(INFO) << "GLONASS GNAV Ephemeris have been received on channel" << d_channel << " from satellite " << d_satellite;
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}
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if (d_nav.have_new_utc_model() == true)
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{
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// get object for this SV (mandatory)
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std::shared_ptr<Glonass_Gnav_Utc_Model> tmp_obj = std::make_shared<Glonass_Gnav_Utc_Model>(d_nav.get_utc_model());
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this->message_port_pub(pmt::mp("telemetry"), pmt::make_any(tmp_obj));
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LOG(INFO) << "GLONASS GNAV UTC Model have been received on channel" << d_channel << " from satellite " << d_satellite;
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}
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if (d_nav.have_new_almanac() == true)
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{
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unsigned int slot_nbr = d_nav.i_alm_satellite_slot_number;
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std::shared_ptr<Glonass_Gnav_Almanac> tmp_obj = std::make_shared<Glonass_Gnav_Almanac>(d_nav.get_almanac(slot_nbr));
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this->message_port_pub(pmt::mp("telemetry"), pmt::make_any(tmp_obj));
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LOG(INFO) << "GLONASS GNAV Almanac have been received on channel" << d_channel << " in slot number " << slot_nbr;
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}
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// 5. Update satellite information on system
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if (d_nav.flag_update_slot_number == true)
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{
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LOG(INFO) << "GLONASS GNAV Slot Number Identified on channel " << d_channel;
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d_satellite.update_PRN(d_nav.gnav_ephemeris.d_n);
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d_satellite.what_block(d_satellite.get_system(), d_nav.gnav_ephemeris.d_n);
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d_nav.flag_update_slot_number = false;
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}
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}
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int glonass_l2_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
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gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
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{
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int corr_value = 0;
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int preamble_diff = 0;
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Gnss_Synchro **out = reinterpret_cast<Gnss_Synchro **>(&output_items[0]); // Get the output buffer pointer
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const Gnss_Synchro **in = reinterpret_cast<const Gnss_Synchro **>(&input_items[0]); // Get the input buffer pointer
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Gnss_Synchro current_symbol; //structure to save the synchronization information and send the output object to the next block
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//1. Copy the current tracking output
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current_symbol = in[0][0];
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d_symbol_history.push_back(current_symbol); //add new symbol to the symbol queue
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d_sample_counter++; //count for the processed samples
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consume_each(1);
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d_flag_preamble = false;
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unsigned int required_symbols = GLONASS_GNAV_STRING_SYMBOLS;
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if (d_symbol_history.size() > required_symbols)
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{
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//******* preamble correlation ********
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for (int i = 0; i < d_symbols_per_preamble; i++)
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{
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if (d_symbol_history.at(i).Prompt_I < 0) // symbols clipping
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{
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corr_value -= d_preambles_symbols[i];
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}
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else
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{
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corr_value += d_preambles_symbols[i];
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}
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}
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}
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//******* frame sync ******************
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if (d_stat == 0) //no preamble information
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{
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if (abs(corr_value) >= d_symbols_per_preamble)
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{
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// Record the preamble sample stamp
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d_preamble_index = d_sample_counter;
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LOG(INFO) << "Preamble detection for GLONASS L2 C/A SAT " << this->d_satellite;
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// Enter into frame pre-detection status
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d_stat = 1;
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d_preamble_time_samples = d_symbol_history.at(0).Tracking_sample_counter; // record the preamble sample stamp
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}
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}
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else if (d_stat == 1) // posible preamble lock
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{
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if (abs(corr_value) >= d_symbols_per_preamble)
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{
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//check preamble separation
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preamble_diff = d_sample_counter - d_preamble_index;
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// Record the PRN start sample index associated to the preamble
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d_preamble_time_samples = d_symbol_history.at(0).Tracking_sample_counter;
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if (abs(preamble_diff - GLONASS_GNAV_PREAMBLE_PERIOD_SYMBOLS) == 0)
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{
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//try to decode frame
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LOG(INFO) << "Starting string decoder for GLONASS L2 C/A SAT " << this->d_satellite;
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d_preamble_index = d_sample_counter; //record the preamble sample stamp
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d_stat = 2;
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// send asynchronous message to tracking to inform of frame sync and extend correlation time
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pmt::pmt_t value = pmt::from_double(static_cast<double>(d_preamble_time_samples) / static_cast<double>(d_symbol_history.at(0).fs) - 0.001);
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this->message_port_pub(pmt::mp("preamble_timestamp_s"), value);
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}
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else
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{
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if (preamble_diff > GLONASS_GNAV_PREAMBLE_PERIOD_SYMBOLS)
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{
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d_stat = 0; // start again
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}
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DLOG(INFO) << "Failed string decoder for GLONASS L2 C/A SAT " << this->d_satellite;
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}
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}
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}
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else if (d_stat == 2)
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{
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// FIXME: The preamble index marks the first symbol of the string count. Here I just wait for another full string to be received before processing
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if (d_sample_counter == d_preamble_index + GLONASS_GNAV_STRING_SYMBOLS)
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{
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// NEW GLONASS string received
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// 0. fetch the symbols into an array
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int string_length = GLONASS_GNAV_STRING_SYMBOLS - d_symbols_per_preamble;
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double string_symbols[GLONASS_GNAV_DATA_SYMBOLS] = {0};
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//******* SYMBOL TO BIT *******
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for (int i = 0; i < string_length; i++)
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{
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if (corr_value > 0)
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{
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string_symbols[i] = d_symbol_history.at(i + d_symbols_per_preamble).Prompt_I; // because last symbol of the preamble is just received now!
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}
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else
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{
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string_symbols[i] = -d_symbol_history.at(i + d_symbols_per_preamble).Prompt_I; // because last symbol of the preamble is just received now!
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}
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}
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//call the decoder
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decode_string(string_symbols, string_length);
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if (d_nav.flag_CRC_test == true)
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{
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d_CRC_error_counter = 0;
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d_flag_preamble = true; //valid preamble indicator (initialized to false every work())
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d_preamble_index = d_sample_counter; //record the preamble sample stamp (t_P)
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if (!d_flag_frame_sync)
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{
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d_flag_frame_sync = true;
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DLOG(INFO) << " Frame sync SAT " << this->d_satellite << " with preamble start at "
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<< d_symbol_history.at(0).Tracking_sample_counter << " [samples]";
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}
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}
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else
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{
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d_CRC_error_counter++;
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d_preamble_index = d_sample_counter; //record the preamble sample stamp
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if (d_CRC_error_counter > CRC_ERROR_LIMIT)
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{
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LOG(INFO) << "Lost of frame sync SAT " << this->d_satellite;
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d_flag_frame_sync = false;
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d_stat = 0;
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}
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}
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}
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}
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// UPDATE GNSS SYNCHRO DATA
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//2. Add the telemetry decoder information
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if (this->d_flag_preamble == true and d_nav.flag_TOW_new == true)
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//update TOW at the preamble instant
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{
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d_TOW_at_current_symbol = floor((d_nav.gnav_ephemeris.d_TOW - GLONASS_GNAV_PREAMBLE_DURATION_S) * 1000) / 1000;
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d_nav.flag_TOW_new = false;
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}
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else //if there is not a new preamble, we define the TOW of the current symbol
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{
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d_TOW_at_current_symbol = d_TOW_at_current_symbol + GLONASS_L2_CA_CODE_PERIOD;
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}
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//if (d_flag_frame_sync == true and d_nav.flag_TOW_set==true and d_nav.flag_CRC_test == true)
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// if(d_nav.flag_GGTO_1 == true and d_nav.flag_GGTO_2 == true and d_nav.flag_GGTO_3 == true and d_nav.flag_GGTO_4 == true) //all GGTO parameters arrived
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// {
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// delta_t = d_nav.A_0G_10 + d_nav.A_1G_10 * (d_TOW_at_current_symbol - d_nav.t_0G_10 + 604800.0 * (fmod((d_nav.WN_0 - d_nav.WN_0G_10), 64)));
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// }
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if (d_flag_frame_sync == true and d_nav.flag_TOW_set == true)
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{
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current_symbol.Flag_valid_word = true;
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}
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else
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{
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current_symbol.Flag_valid_word = false;
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}
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current_symbol.PRN = this->d_satellite.get_PRN();
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current_symbol.TOW_at_current_symbol_s = d_TOW_at_current_symbol;
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current_symbol.TOW_at_current_symbol_s -= delta_t; // Galileo to GPS TOW
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if (d_dump == true)
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{
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// MULTIPLEXED FILE RECORDING - Record results to file
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try
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{
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double tmp_double;
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unsigned long int tmp_ulong_int;
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tmp_double = d_TOW_at_current_symbol;
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d_dump_file.write(reinterpret_cast<char *>(&tmp_double), sizeof(double));
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tmp_ulong_int = current_symbol.Tracking_sample_counter;
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d_dump_file.write(reinterpret_cast<char *>(&tmp_ulong_int), sizeof(unsigned long int));
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tmp_double = 0;
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d_dump_file.write(reinterpret_cast<char *>(&tmp_double), sizeof(double));
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}
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catch (const std::ifstream::failure &e)
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{
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LOG(WARNING) << "Exception writing observables dump file " << e.what();
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}
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}
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// remove used symbols from history
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if (d_symbol_history.size() > required_symbols)
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{
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d_symbol_history.pop_front();
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}
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//3. Make the output (copy the object contents to the GNURadio reserved memory)
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*out[0] = current_symbol;
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return 1;
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}
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void glonass_l2_ca_telemetry_decoder_cc::set_satellite(const Gnss_Satellite &satellite)
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{
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d_satellite = Gnss_Satellite(satellite.get_system(), satellite.get_PRN());
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DLOG(INFO) << "Setting decoder Finite State Machine to satellite " << d_satellite;
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DLOG(INFO) << "Navigation Satellite set to " << d_satellite;
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}
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void glonass_l2_ca_telemetry_decoder_cc::set_channel(int channel)
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{
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d_channel = channel;
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LOG(INFO) << "Navigation channel set to " << channel;
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// ############# ENABLE DATA FILE LOG #################
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if (d_dump == true)
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{
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if (d_dump_file.is_open() == false)
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{
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try
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{
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d_dump_filename = "telemetry";
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|
d_dump_filename.append(boost::lexical_cast<std::string>(d_channel));
|
|
d_dump_filename.append(".dat");
|
|
d_dump_file.exceptions(std::ifstream::failbit | std::ifstream::badbit);
|
|
d_dump_file.open(d_dump_filename.c_str(), std::ios::out | std::ios::binary);
|
|
LOG(INFO) << "Telemetry decoder dump enabled on channel " << d_channel << " Log file: " << d_dump_filename.c_str();
|
|
}
|
|
catch (const std::ifstream::failure &e)
|
|
{
|
|
LOG(WARNING) << "channel " << d_channel << ": exception opening Glonass TLM dump file. " << e.what();
|
|
}
|
|
}
|
|
}
|
|
}
|