mirror of https://github.com/gnss-sdr/gnss-sdr
306 lines
14 KiB
C++
306 lines
14 KiB
C++
/*!
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* \file gps_l1_ca_observables_cc.cc
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* \brief Implementation of the pseudorange computation block for GPS L1 C/A
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* \author Javier Arribas, 2011. jarribas(at)cttc.es
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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 "gps_l1_ca_observables_cc.h"
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#include <iostream>
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#include <sstream>
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#include <vector>
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#include <map>
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#include <algorithm>
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#include <bitset>
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#include <cmath>
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#include "math.h"
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#include "control_message_factory.h"
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#include <gnuradio/gr_io_signature.h>
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#include <glog/log_severity.h>
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#include <glog/logging.h>
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#include "gnss_synchro.h"
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using google::LogMessage;
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gps_l1_ca_observables_cc_sptr
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gps_l1_ca_make_observables_cc(unsigned int nchannels, gr_msg_queue_sptr queue, bool dump, std::string dump_filename, int output_rate_ms, bool flag_averaging)
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{
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return gps_l1_ca_observables_cc_sptr(new gps_l1_ca_observables_cc(nchannels, queue, dump, dump_filename, output_rate_ms, flag_averaging));
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}
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gps_l1_ca_observables_cc::gps_l1_ca_observables_cc(unsigned int nchannels, gr_msg_queue_sptr queue, bool dump, std::string dump_filename, int output_rate_ms, bool flag_averaging) :
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gr_block ("gps_l1_ca_observables_cc", gr_make_io_signature (nchannels, nchannels, sizeof(Gnss_Synchro)),
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gr_make_io_signature(nchannels, nchannels, sizeof(Gnss_Synchro)))
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{
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// initialize internal vars
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d_queue = queue;
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d_dump = dump;
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d_nchannels = nchannels;
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d_output_rate_ms = output_rate_ms;
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d_history_gnss_synchro_deque = new std::deque<Gnss_Synchro>[d_nchannels];
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d_dump_filename = dump_filename;
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d_flag_averaging = flag_averaging;
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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_file.exceptions (std::ifstream::failbit | std::ifstream::badbit );
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d_dump_file.open(d_dump_filename.c_str(), std::ios::out | std::ios::binary);
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std::cout << "Observables dump enabled Log file: " << d_dump_filename.c_str() << std::endl;
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}
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catch (std::ifstream::failure e)
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{
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std::cout << "Exception opening observables dump file " << e.what() << std::endl;
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}
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}
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}
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}
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gps_l1_ca_observables_cc::~gps_l1_ca_observables_cc()
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{
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d_dump_file.close();
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delete[] d_history_gnss_synchro_deque;
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}
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bool pairCompare_gnss_synchro_Prn_delay_ms( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
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{
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return (a.second.Prn_timestamp_ms) < (b.second.Prn_timestamp_ms);
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}
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bool pairCompare_gnss_synchro_preamble_symbol_count( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
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{
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return (a.second.Preamble_symbol_counter) < (b.second.Preamble_symbol_counter);
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}
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bool pairCompare_gnss_synchro_preamble_delay_ms( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
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{
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return (a.second.Preamble_timestamp_ms) < (b.second.Preamble_timestamp_ms);
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}
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bool pairCompare_double( std::pair<int,double> a, std::pair<int,double> b)
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{
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return (a.second) < (b.second);
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}
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void clearQueue( std::deque<double> &q )
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{
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std::deque<double> empty;
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std::swap(q, empty);
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}
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int gps_l1_ca_observables_cc::general_work (int noutput_items, gr_vector_int &ninput_items,
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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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Gnss_Synchro **in = (Gnss_Synchro **) &input_items[0]; //Get the input pointer
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Gnss_Synchro **out = (Gnss_Synchro **) &output_items[0]; //Get the output pointer
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Gnss_Synchro current_gnss_synchro[d_nchannels];
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// Gnss_Synchro current_gnss_synchro[cd_channels];
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std::map<int,Gnss_Synchro> current_gnss_synchro_map;
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std::map<int,Gnss_Synchro> gnss_synchro_aligned_map;
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std::map<int,Gnss_Synchro>::iterator gnss_synchro_iter;
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double traveltime_ms;
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double pseudorange_m;
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d_sample_counter++; //count for the processed samples
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bool flag_history_ok = true; //flag to indicate that all the queues have filled their GNSS SYNCHRO history
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/*
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* 1. Read the GNSS SYNCHRO objects from available channels
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*/
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for (unsigned int i=0; i<d_nchannels ; i++)
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{
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//Copy the telemetry decoder data to local copy
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current_gnss_synchro[i] = in[i][0];
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if (current_gnss_synchro[i].Flag_valid_word) //if this channel have valid word
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{
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//record the word structure in a map for pseudoranges
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current_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(current_gnss_synchro[i].Channel_ID, current_gnss_synchro[i]));
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// RECORD PRN start timestamps history
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if (d_history_gnss_synchro_deque[i].size() < MAX_TOA_DELAY_MS)
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{
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d_history_gnss_synchro_deque[i].push_front(current_gnss_synchro[i]);
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flag_history_ok = false; // at least one channel need more samples
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}
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else
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{
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//clearQueue(d_history_prn_delay_ms[i]); //clear the queue as the preamble arrives
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d_history_gnss_synchro_deque[i].pop_back();
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d_history_gnss_synchro_deque[i].push_front(current_gnss_synchro[i]);
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}
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}
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}
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/*
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* 1.2 Assume no satellites in tracking
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*/
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for (unsigned int i=0; i<d_nchannels ; i++)
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{
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current_gnss_synchro[i].Flag_valid_pseudorange = false;
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current_gnss_synchro[i].Pseudorange_m = 0.0;
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current_gnss_synchro[i].Pseudorange_symbol_shift = 0.0;
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}
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/*
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* 2. Compute RAW pseudoranges: Use only the valid channels (channels that are tracking a satellite)
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*/
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if(current_gnss_synchro_map.size() > 0 and flag_history_ok == true)
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{
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/*
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* 2.1 Find the correct symbol timestamp in the gnss_synchro history: we have to compare timestamps between channels on the SAME symbol
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* (common TX time algorithm)
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*/
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double min_preamble_delay_ms;
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double max_preamble_delay_ms;
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int current_symbol = 0;
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int reference_channel;
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int history_shift;
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Gnss_Synchro tmp_gnss_synchro;
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gnss_synchro_iter = min_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), pairCompare_gnss_synchro_preamble_delay_ms);
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min_preamble_delay_ms = gnss_synchro_iter->second.Preamble_timestamp_ms; //[ms]
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gnss_synchro_iter = max_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), pairCompare_gnss_synchro_preamble_delay_ms);
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max_preamble_delay_ms = gnss_synchro_iter->second.Preamble_timestamp_ms; //[ms]
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if ((max_preamble_delay_ms - min_preamble_delay_ms) < MAX_TOA_DELAY_MS)
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{
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// we have a valid information set. Its time to align the symbols information
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// what is the most delayed symbol in the current set? -> this will be the reference symbol
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gnss_synchro_iter = min_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), pairCompare_gnss_synchro_preamble_symbol_count);
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current_symbol = gnss_synchro_iter->second.Preamble_symbol_counter;
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reference_channel = gnss_synchro_iter->second.Channel_ID;
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// save it in the aligned symbols map
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gnss_synchro_aligned_map.insert(std::pair<int,Gnss_Synchro>(gnss_synchro_iter->second.Channel_ID, gnss_synchro_iter->second));
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// Now find where the same symbols were in the rest of the channels searching in the symbol history
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for(gnss_synchro_iter = current_gnss_synchro_map.begin(); gnss_synchro_iter != current_gnss_synchro_map.end(); gnss_synchro_iter++)
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{
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//TODO: Replace the loop using current current_symbol-Preamble_symbol_counter
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if (reference_channel != gnss_synchro_iter->second.Channel_ID)
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{
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// compute the required symbol history shift in order to match the reference symbol
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history_shift = gnss_synchro_iter->second.Preamble_symbol_counter - current_symbol;
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if (history_shift < (int)MAX_TOA_DELAY_MS ) // and history_shift>=0)
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{
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tmp_gnss_synchro= d_history_gnss_synchro_deque[gnss_synchro_iter->second.Channel_ID][history_shift];
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gnss_synchro_aligned_map.insert(std::pair<int,Gnss_Synchro>(gnss_synchro_iter->second.Channel_ID, tmp_gnss_synchro));
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}
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}
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}
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}
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/*
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* 3 Compute the pseudoranges using the aligned data map
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*/
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double min_symbol_timestamp_ms;
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double max_symbol_timestamp_ms;
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gnss_synchro_iter = min_element(gnss_synchro_aligned_map.begin(), gnss_synchro_aligned_map.end(), pairCompare_gnss_synchro_Prn_delay_ms);
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min_symbol_timestamp_ms = gnss_synchro_iter->second.Prn_timestamp_ms; //[ms]
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gnss_synchro_iter = max_element(gnss_synchro_aligned_map.begin(), gnss_synchro_aligned_map.end(), pairCompare_gnss_synchro_Prn_delay_ms);
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max_symbol_timestamp_ms = gnss_synchro_iter->second.Prn_timestamp_ms; //[ms]
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// check again if this is a valid set of observations
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if ((max_symbol_timestamp_ms - min_symbol_timestamp_ms) < MAX_TOA_DELAY_MS)
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/*
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* 2.3 compute the pseudoranges
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*/
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{
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for(gnss_synchro_iter = gnss_synchro_aligned_map.begin(); gnss_synchro_iter != gnss_synchro_aligned_map.end(); gnss_synchro_iter++)
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{
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traveltime_ms = gnss_synchro_iter->second.Prn_timestamp_ms - min_symbol_timestamp_ms + GPS_STARTOFFSET_ms; //[ms]
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pseudorange_m = traveltime_ms * GPS_C_m_ms; // [m]
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// update the pseudorange object
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID] = gnss_synchro_iter->second;
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Pseudorange_m = pseudorange_m;
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Pseudorange_symbol_shift = (double)current_symbol; // number of symbols shifted from preamble start symbol
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Flag_valid_pseudorange = true;
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].Pseudorange_timestamp_ms = max_symbol_timestamp_ms;
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}
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}
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}
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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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for (unsigned int i=0; i<d_nchannels ; i++)
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{
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tmp_double = current_gnss_synchro[i].Preamble_timestamp_ms;
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d_dump_file.write((char*)&tmp_double, sizeof(double));
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tmp_double = current_gnss_synchro[i].Prn_timestamp_ms;
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d_dump_file.write((char*)&tmp_double, sizeof(double));
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tmp_double = current_gnss_synchro[i].Pseudorange_m;
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d_dump_file.write((char*)&tmp_double, sizeof(double));
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tmp_double = current_gnss_synchro[i].Pseudorange_symbol_shift;
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d_dump_file.write((char*)&tmp_double, sizeof(double));
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tmp_double = current_gnss_synchro[i].PRN;
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d_dump_file.write((char*)&tmp_double, sizeof(double));
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}
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}
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catch (std::ifstream::failure e)
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{
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std::cout << "Exception writing observables dump file " << e.what() << std::endl;
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}
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}
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consume_each(1); //one by one
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// mod 8/4/2012: always make the observables output
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//if ((d_sample_counter % d_output_rate_ms) == 0)
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// {
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for (unsigned int i=0; i<d_nchannels ; i++)
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{
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*out[i] = current_gnss_synchro[i];
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}
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return 1; //Output the observables
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// }
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//else
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// {
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// return 0; //hold on
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// }
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}
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