mirror of https://github.com/gnss-sdr/gnss-sdr
205 lines
8.8 KiB
C++
205 lines
8.8 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 "control_message_factory.h"
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#include <gnuradio/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, boost::shared_ptr<gr::msg_queue> 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, boost::shared_ptr<gr::msg_queue> 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::io_signature::make(nchannels, nchannels, sizeof(Gnss_Synchro)),
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gr::io_signature::make(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_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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}
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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_d_TOW_at_current_symbol( std::pair<int,Gnss_Synchro> a, std::pair<int,Gnss_Synchro> b)
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{
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return (a.second.d_TOW_at_current_symbol) < (b.second.d_TOW_at_current_symbol);
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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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std::map<int,Gnss_Synchro> current_gnss_synchro_map;
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std::map<int,Gnss_Synchro>::iterator gnss_synchro_iter;
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d_sample_counter++; //count for the processed samples
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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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/*
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* 1.2 Assume no valid pseudoranges
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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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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 pseudorange computation
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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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}
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}
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/*
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* 2. Compute RAW pseudoranges using COMMON RECEPTION TIME algorithm. 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)
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{
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/*
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* 2.1 Use CURRENT set of measurements and find the nearest satellite
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* common RX time algorithm
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*/
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//;
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// what is the most recent symbol TOW in the current set? -> this will be the reference symbol
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gnss_synchro_iter = max_element(current_gnss_synchro_map.begin(), current_gnss_synchro_map.end(), pairCompare_gnss_synchro_d_TOW_at_current_symbol);
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double d_TOW_reference = gnss_synchro_iter->second.d_TOW_at_current_symbol;
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double d_ref_PRN_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms;
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//int reference_channel= gnss_synchro_iter->second.Channel_ID;
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// Now compute RX time differences due to the PRN alignement in the correlators
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double traveltime_ms;
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double pseudorange_m;
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double delta_rx_time_ms;
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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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// compute the required symbol history shift in order to match the reference symbol
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delta_rx_time_ms = gnss_synchro_iter->second.Prn_timestamp_ms-d_ref_PRN_rx_time_ms;
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//std::cout<<"delta_rx_time_ms="<<delta_rx_time_ms<<std::endl;
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//compute the pseudorange
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traveltime_ms = (d_TOW_reference-gnss_synchro_iter->second.d_TOW_at_current_symbol)*1000.0 + delta_rx_time_ms + GPS_STARTOFFSET_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].Flag_valid_pseudorange = true;
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current_gnss_synchro[gnss_synchro_iter->second.Channel_ID].d_TOW_at_current_symbol = round(d_TOW_reference*1000)/1000 + GPS_STARTOFFSET_ms/1000.0;
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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].d_TOW_at_current_symbol;
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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 = 0;
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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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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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