gnss-sdr/src/algorithms/observables/gnuradio_blocks/hybrid_observables_cc.cc

/*!
 * \file hybrid_observables_cc.cc
 * \brief Implementation of the pseudorange computation block for Galileo E1
 * \author Javier Arribas 2017. jarribas(at)cttc.es
 *
 * -------------------------------------------------------------------------
 *
 * Copyright (C) 2010-2015  (see AUTHORS file for a list of contributors)
 *
 * GNSS-SDR is a software defined Global Navigation
 *          Satellite Systems receiver
 *
 * This file is part of GNSS-SDR.
 *
 * GNSS-SDR is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * GNSS-SDR is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
 *
 * -------------------------------------------------------------------------
 */

#include "hybrid_observables_cc.h"
#include <algorithm>
#include <cmath>
#include <iostream>
#include <map>
#include <vector>
#include <utility>
#include <armadillo>
#include <gnuradio/io_signature.h>
#include <glog/logging.h>
#include "Galileo_E1.h"
#include "GPS_L1_CA.h"

using google::LogMessage;


hybrid_observables_cc_sptr hybrid_make_observables_cc(unsigned int nchannels, bool dump, std::string dump_filename, unsigned int deep_history)
{
  return hybrid_observables_cc_sptr(new hybrid_observables_cc(nchannels, dump, dump_filename, deep_history));
}


hybrid_observables_cc::hybrid_observables_cc(unsigned int nchannels, bool dump, std::string dump_filename, unsigned int deep_history) :
                	  gr::block("hybrid_observables_cc", gr::io_signature::make(nchannels, nchannels, sizeof(Gnss_Synchro)),
								gr::io_signature::make(nchannels, nchannels, sizeof(Gnss_Synchro)))
{
  // initialize internal vars
  d_dump = dump;
  d_nchannels = nchannels;
  d_dump_filename = dump_filename;
  history_deep = deep_history;
  T_rx_s = 0.0;
  T_rx_step_s = 1e-3;// todo: move to gnss-sdr config
  for (unsigned int i = 0; i < d_nchannels; i++)
	{
	  d_gnss_synchro_history_queue.push_back(std::deque<Gnss_Synchro>());
	}
  //todo: this is a gnuradio scheduler hack.
  // Migrate the queues to gnuradio set_history to see if the scheduler can handle
  // the multiple output flow
  d_max_noutputs = 100;
  this->set_min_noutput_items(100);

  // ############# ENABLE DATA FILE LOG #################
  if (d_dump == true)
	{
	  if (d_dump_file.is_open() == false)
		{
		  try
		  {
			  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) << "Observables dump enabled Log file: " << d_dump_filename.c_str();
		  }
		  catch (const std::ifstream::failure & e)
		  {
			  LOG(WARNING) << "Exception opening observables dump file " << e.what();
		  }
		}
	}
}


hybrid_observables_cc::~hybrid_observables_cc()
{
  if (d_dump_file.is_open() == true)
	{
	  try
	  {
		  d_dump_file.close();
	  }
	  catch(const std::exception & ex)
	  {
		  LOG(WARNING) << "Exception in destructor closing the dump file " << ex.what();
	  }
	}
}


bool Hybrid_pairCompare_gnss_synchro_sample_counter(const std::pair<int,Gnss_Synchro>& a, const std::pair<int,Gnss_Synchro>& b)
{
  return (a.second.Tracking_sample_counter) < (b.second.Tracking_sample_counter);
}


bool Hybrid_valueCompare_gnss_synchro_sample_counter(const Gnss_Synchro& a, unsigned long int b)
{
  return (a.Tracking_sample_counter) < (b);
}


bool Hybrid_valueCompare_gnss_synchro_receiver_time(const Gnss_Synchro& a, double b)
{
  return (((double)a.Tracking_sample_counter+a.Code_phase_samples)/(double)a.fs) < (b);
}


bool Hybrid_pairCompare_gnss_synchro_d_TOW(const std::pair<int,Gnss_Synchro>& a, const std::pair<int,Gnss_Synchro>& b)
{
  return (a.second.TOW_at_current_symbol_s) < (b.second.TOW_at_current_symbol_s);
}


bool Hybrid_valueCompare_gnss_synchro_d_TOW(const Gnss_Synchro& a, double b)
{
  return (a.TOW_at_current_symbol_s) < (b);
}


int hybrid_observables_cc::general_work (int noutput_items,
										 gr_vector_int &ninput_items,
										 gr_vector_const_void_star &input_items,
										 gr_vector_void_star &output_items)
{
  Gnss_Synchro **in = (Gnss_Synchro **)  &input_items[0];   // Get the input pointer
  Gnss_Synchro **out = (Gnss_Synchro **)  &output_items[0]; // Get the output pointer
  int n_outputs = 0;
  int n_consume[d_nchannels];
  double past_history_s = 100e-3;

  Gnss_Synchro current_gnss_synchro[d_nchannels];

  /*
   * 1. Read the GNSS SYNCHRO objects from available channels.
   *  Multi-rate GNURADIO Block. Read how many input items are avaliable in each channel
   *  Record all synchronization data into queues
   */
  for (unsigned int i = 0; i < d_nchannels; i++)
	{
	  n_consume[i] = ninput_items[i];// full throttle
	  for (int j = 0; j < n_consume[i]; j++)
		{
		  d_gnss_synchro_history_queue[i].push_back(in[i][j]);
		}
	  //std::cout<<"push["<<i<<"] items "<<n_consume[i]
	  ///         <<" latest T_rx: "<<(double)in[i][ninput_items[i]-1].Tracking_sample_counter/(double)in[i][ninput_items[i]-1].fs
	  //         <<" [s] q size: "
	  //         <<d_gnss_synchro_history_queue[i].size()
	  //         <<std::endl;
	}

  bool channel_history_ok;
  do
	{
	  channel_history_ok = true;
	  for (unsigned int i = 0; i < d_nchannels; i++)
		{
		  if (d_gnss_synchro_history_queue[i].size() < history_deep)
			{
			  channel_history_ok = false;
			}

		}
	  if (channel_history_ok == true)
		{
		  std::map<int,Gnss_Synchro>::iterator gnss_synchro_map_iter;
		  std::deque<Gnss_Synchro>::iterator gnss_synchro_deque_iter;

		  //1. If the RX time is not set, set the Rx time
		  if (T_rx_s == 0)
			{
			  //0. Read a gnss_synchro snapshot from the queue and store it in a map
			  std::map<int,Gnss_Synchro> gnss_synchro_map;
			  for (unsigned int i = 0; i < d_nchannels; i++)
				{
				  gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(
					  d_gnss_synchro_history_queue[i].front().Channel_ID,
					  d_gnss_synchro_history_queue[i].front()));
				}
			  gnss_synchro_map_iter = min_element(gnss_synchro_map.begin(),
												  gnss_synchro_map.end(),
												  Hybrid_pairCompare_gnss_synchro_sample_counter);
			  T_rx_s = (double)gnss_synchro_map_iter->second.Tracking_sample_counter / (double)gnss_synchro_map_iter->second.fs;
			  T_rx_s = floor(T_rx_s * 1000.0) / 1000.0; // truncate to ms
			  T_rx_s += past_history_s; // increase T_rx to have a minimum past history to interpolate
			}

		  //2. Realign RX time in all valid channels
		  std::map<int,Gnss_Synchro> realigned_gnss_synchro_map; //container for the aligned set of observables for the selected T_rx
		  std::map<int,Gnss_Synchro> adjacent_gnss_synchro_map;  //container for the previous observable values to interpolate
		  //shift channels history to match the reference TOW
		  for (unsigned int i = 0; i < d_nchannels; i++)
			{
			  gnss_synchro_deque_iter = std::lower_bound(d_gnss_synchro_history_queue[i].begin(),
														 d_gnss_synchro_history_queue[i].end(),
														 T_rx_s,
														 Hybrid_valueCompare_gnss_synchro_receiver_time);
			  if (gnss_synchro_deque_iter != d_gnss_synchro_history_queue[i].end())
				{
				  if (gnss_synchro_deque_iter->Flag_valid_word == true)
					{
					  double T_rx_channel = (double)gnss_synchro_deque_iter->Tracking_sample_counter / (double)gnss_synchro_deque_iter->fs;
					  double delta_T_rx_s = T_rx_channel - T_rx_s;

					  //check that T_rx difference is less than a threshold (the correlation interval)
					  if (delta_T_rx_s * 1000.0 < (double)gnss_synchro_deque_iter->correlation_length_ms)
						{
						  //record the word structure in a map for pseudorange computation
						  //save the previous observable
						  int distance = std::distance(d_gnss_synchro_history_queue[i].begin(), gnss_synchro_deque_iter);
						  if (distance > 0)
							{
							  if (d_gnss_synchro_history_queue[i].at(distance-1).Flag_valid_word)
								{
								  double T_rx_channel_prev = (double)d_gnss_synchro_history_queue[i].at(distance - 1).Tracking_sample_counter / (double)gnss_synchro_deque_iter->fs;
								  double delta_T_rx_s_prev = T_rx_channel_prev - T_rx_s;
								  if (fabs(delta_T_rx_s_prev) < fabs(delta_T_rx_s))
									{
									  realigned_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(
										  d_gnss_synchro_history_queue[i].at(distance-1).Channel_ID,
										  d_gnss_synchro_history_queue[i].at(distance-1)));
									  adjacent_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(gnss_synchro_deque_iter->Channel_ID, *gnss_synchro_deque_iter));
									}
								  else
									{
									  realigned_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(gnss_synchro_deque_iter->Channel_ID, *gnss_synchro_deque_iter));
									  adjacent_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(
										  d_gnss_synchro_history_queue[i].at(distance-1).Channel_ID,
										  d_gnss_synchro_history_queue[i].at(distance-1)));
									}
								}
							}
						  else
							{
							  realigned_gnss_synchro_map.insert(std::pair<int, Gnss_Synchro>(gnss_synchro_deque_iter->Channel_ID, *gnss_synchro_deque_iter));
							}

						}
					  else
						{
						  //std::cout<<"ch["<<i<<"] delta_T_rx:"<<delta_T_rx_s*1000.0<<std::endl;
						}
					}
				}
			}

		  if(!realigned_gnss_synchro_map.empty())
			{
			  /*
			   *  2.1 Use CURRENT set of measurements and find the nearest satellite
			   *  common RX time algorithm
			   */
			  // what is the most recent symbol TOW in the current set? -> this will be the reference symbol
			  gnss_synchro_map_iter = max_element(realigned_gnss_synchro_map.begin(),
												  realigned_gnss_synchro_map.end(),
												  Hybrid_pairCompare_gnss_synchro_d_TOW);
			  double ref_fs_hz = (double)gnss_synchro_map_iter->second.fs;

			  // compute interpolated TOW value at T_rx_s
			  int ref_channel_key = gnss_synchro_map_iter->second.Channel_ID;
			  Gnss_Synchro adj_obs = adjacent_gnss_synchro_map.at(ref_channel_key);
			  double ref_adj_T_rx_s = (double)adj_obs.Tracking_sample_counter / ref_fs_hz + adj_obs.Code_phase_samples / ref_fs_hz;

			  double d_TOW_reference = gnss_synchro_map_iter->second.TOW_at_current_symbol_s;
			  double d_ref_T_rx_s = (double)gnss_synchro_map_iter->second.Tracking_sample_counter / ref_fs_hz + gnss_synchro_map_iter->second.Code_phase_samples / ref_fs_hz;

			  double selected_T_rx_s = T_rx_s;
			  // two points linear interpolation using adjacent (adj) values: y=y1+(x-x1)*(y2-y1)/(x2-x1)
			  double ref_TOW_at_T_rx_s = adj_obs.TOW_at_current_symbol_s + (selected_T_rx_s - ref_adj_T_rx_s)
                                	* (d_TOW_reference - adj_obs.TOW_at_current_symbol_s) / (d_ref_T_rx_s - ref_adj_T_rx_s);

			  // Now compute RX time differences due to the PRN alignment in the correlators
			  double traveltime_ms;
			  double pseudorange_m;
			  double channel_T_rx_s;
			  double channel_fs_hz;
			  double channel_TOW_s;
			  double delta_T_rx_s;
			  for(gnss_synchro_map_iter = realigned_gnss_synchro_map.begin(); gnss_synchro_map_iter != realigned_gnss_synchro_map.end(); gnss_synchro_map_iter++)
				{
				  channel_fs_hz = (double)gnss_synchro_map_iter->second.fs;
				  channel_TOW_s = gnss_synchro_map_iter->second.TOW_at_current_symbol_s;
				  channel_T_rx_s = (double)gnss_synchro_map_iter->second.Tracking_sample_counter / channel_fs_hz + gnss_synchro_map_iter->second.Code_phase_samples / channel_fs_hz;
				  // compute interpolated observation values
				  // two points linear interpolation using adjacent (adj) values: y=y1+(x-x1)*(y2-y1)/(x2-x1)
					  // TOW at the selected receiver time T_rx_s
					  int element_key = gnss_synchro_map_iter->second.Channel_ID;
					  adj_obs = adjacent_gnss_synchro_map.at(element_key);

					  double adj_T_rx_s = (double)adj_obs.Tracking_sample_counter / channel_fs_hz + adj_obs.Code_phase_samples / channel_fs_hz;

					  double channel_TOW_at_T_rx_s = adj_obs.TOW_at_current_symbol_s + (selected_T_rx_s - adj_T_rx_s) * (channel_TOW_s - adj_obs.TOW_at_current_symbol_s) / (channel_T_rx_s - adj_T_rx_s);

					  //Doppler and Accumulated carrier phase
					  double Carrier_phase_lin_rads = adj_obs.Carrier_phase_rads + (selected_T_rx_s - adj_T_rx_s) * (gnss_synchro_map_iter->second.Carrier_phase_rads - adj_obs.Carrier_phase_rads) / (channel_T_rx_s - adj_T_rx_s);
					  double Carrier_Doppler_lin_hz = adj_obs.Carrier_Doppler_hz + (selected_T_rx_s - adj_T_rx_s) * (gnss_synchro_map_iter->second.Carrier_Doppler_hz - adj_obs.Carrier_Doppler_hz) / (channel_T_rx_s - adj_T_rx_s);

					  //compute the pseudorange (no rx time offset correction)
					  traveltime_ms = (ref_TOW_at_T_rx_s - channel_TOW_at_T_rx_s) * 1000.0 + GPS_STARTOFFSET_ms;
					  //convert to meters
					  pseudorange_m = traveltime_ms * GPS_C_m_ms; // [m]
					  // update the pseudorange object
					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID] = gnss_synchro_map_iter->second;
					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID].Pseudorange_m = pseudorange_m;
					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID].Flag_valid_pseudorange = true;
					  // Save the estimated RX time (no RX clock offset correction yet!)
					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID].RX_time = ref_TOW_at_T_rx_s + GPS_STARTOFFSET_ms / 1000.0;

					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID].Carrier_phase_rads = Carrier_phase_lin_rads;
					  current_gnss_synchro[gnss_synchro_map_iter->second.Channel_ID].Carrier_Doppler_hz = Carrier_Doppler_lin_hz;
				}

			  if(d_dump == true)
				{
				  // MULTIPLEXED FILE RECORDING - Record results to file
				  try
				  {
					  double tmp_double;
					  for (unsigned int i = 0; i < d_nchannels; i++)
						{
						  tmp_double = current_gnss_synchro[i].RX_time;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].TOW_at_current_symbol_s;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].Carrier_Doppler_hz;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].Carrier_phase_rads/GPS_TWO_PI;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].Pseudorange_m;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].PRN;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						  tmp_double = current_gnss_synchro[i].Flag_valid_pseudorange;
						  d_dump_file.write((char*)&tmp_double, sizeof(double));
						}
				  }
				  catch (const std::ifstream::failure& e)
				  {
					  LOG(WARNING) << "Exception writing observables dump file " << e.what();
				  }
				}

			  for (unsigned int i = 0; i < d_nchannels; i++)
				{
				  out[i][n_outputs] = current_gnss_synchro[i];
				}

			  n_outputs++;
			}

		  //Move RX time
		  T_rx_s = T_rx_s + T_rx_step_s;
		  //pop old elements from queue
		  for (unsigned int i = 0; i < d_nchannels; i++)
			{
			  while (d_gnss_synchro_history_queue[i].front().Tracking_sample_counter / (double)d_gnss_synchro_history_queue[i].front().fs < (T_rx_s - past_history_s))
				{
				  d_gnss_synchro_history_queue[i].pop_front();
				}
			}
		}
	}while(channel_history_ok == true && d_max_noutputs>n_outputs);

  //Multi-rate consume!
  for (unsigned int i = 0; i < d_nchannels; i++)
	{
	  consume(i, n_consume[i]); //which input, how many items
	}

  return n_outputs;
}