gnss-sdr/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test.cc

/*!
 * \file tracking_test.cc
 * \brief  This class implements a tracking Pull-In test for GPS_L1_CA_DLL_PLL_Tracking
 *  implementation based on some input parameters.
 * \author Javier Arribas, 2018. jarribas(at)cttc.es
 *
 *
 * -----------------------------------------------------------------------------
 *
 * GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
 * This file is part of GNSS-SDR.
 *
 * Copyright (C) 2012-2020  (see AUTHORS file for a list of contributors)
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * -----------------------------------------------------------------------------
 */

#include "GPS_L1_CA.h"
#include "GPS_L2C.h"
#include "GPS_L5.h"
#include "Galileo_E1.h"
#include "Galileo_E5a.h"
#include "acquisition_msg_rx.h"
#include "concurrent_queue.h"
#include "galileo_e1_pcps_ambiguous_acquisition.h"
#include "galileo_e5a_noncoherent_iq_acquisition_caf.h"
#include "galileo_e5a_pcps_acquisition.h"
#include "gnss_block_factory.h"
#include "gnss_block_interface.h"
#include "gnss_sdr_filesystem.h"
#include "gnss_sdr_valve.h"
#include "gnuplot_i.h"
#include "gps_l1_ca_pcps_acquisition.h"
#include "gps_l1_ca_pcps_acquisition_fine_doppler.h"
#include "gps_l2_m_pcps_acquisition.h"
#include "gps_l5i_pcps_acquisition.h"
#include "in_memory_configuration.h"
#include "signal_generator_flags.h"
#include "test_flags.h"
#include "tracking_dump_reader.h"
#include "tracking_interface.h"
#include "tracking_tests_flags.h"
#include "tracking_true_obs_reader.h"
#include <armadillo>
#include <gnuradio/blocks/file_source.h>
#include <gnuradio/blocks/head.h>
#include <gnuradio/blocks/interleaved_char_to_complex.h>
#include <gnuradio/blocks/null_sink.h>
#include <gnuradio/blocks/skiphead.h>
#include <gnuradio/filter/firdes.h>
#include <gnuradio/top_block.h>
#include <gtest/gtest.h>
#include <pmt/pmt.h>
#include <chrono>
#include <cstdint>
#include <utility>
#include <vector>

#if HAS_GENERIC_LAMBDA
#else
#include <boost/bind/bind.hpp>
#endif

#ifdef GR_GREATER_38
#include <gnuradio/filter/fir_filter_blk.h>
#else
#include <gnuradio/filter/fir_filter_ccf.h>
#endif

#if PMT_USES_BOOST_ANY
namespace wht = boost;
#else
namespace wht = std;
#endif

// ######## GNURADIO TRACKING BLOCK MESSAGE RECEVER #########
class TrackingPullInTest_msg_rx;

using TrackingPullInTest_msg_rx_sptr = gnss_shared_ptr<TrackingPullInTest_msg_rx>;

TrackingPullInTest_msg_rx_sptr TrackingPullInTest_msg_rx_make();

class TrackingPullInTest_msg_rx : public gr::block
{
private:
    friend TrackingPullInTest_msg_rx_sptr TrackingPullInTest_msg_rx_make();
    void msg_handler_channel_events(const pmt::pmt_t msg);
    TrackingPullInTest_msg_rx();

public:
    int rx_message;
    ~TrackingPullInTest_msg_rx();  //!< Default destructor
};


TrackingPullInTest_msg_rx_sptr TrackingPullInTest_msg_rx_make()
{
    return TrackingPullInTest_msg_rx_sptr(new TrackingPullInTest_msg_rx());
}


void TrackingPullInTest_msg_rx::msg_handler_channel_events(const pmt::pmt_t msg)
{
    try
        {
            int64_t message = pmt::to_long(std::move(msg));
            rx_message = message;  // 3 -> loss of lock
            // std::cout << "Received trk message: " << rx_message << '\n';
        }
    catch (const wht::bad_any_cast& e)
        {
            LOG(WARNING) << "msg_handler_tracking Bad cast!";
            rx_message = 0;
        }
}


TrackingPullInTest_msg_rx::TrackingPullInTest_msg_rx() : gr::block("TrackingPullInTest_msg_rx", gr::io_signature::make(0, 0, 0), gr::io_signature::make(0, 0, 0))
{
    this->message_port_register_in(pmt::mp("events"));
    this->set_msg_handler(pmt::mp("events"),
#if HAS_GENERIC_LAMBDA
        [this](auto&& PH1) { msg_handler_channel_events(PH1); });
#else
#if USE_BOOST_BIND_PLACEHOLDERS
        boost::bind(&TrackingPullInTest_msg_rx::msg_handler_channel_events, this, boost::placeholders::_1));
#else
        boost::bind(&TrackingPullInTest_msg_rx::msg_handler_channel_events, this, _1));
#endif
#endif
    rx_message = 0;
}


TrackingPullInTest_msg_rx::~TrackingPullInTest_msg_rx() = default;


// ###########################################################

class TrackingPullInTest : public ::testing::Test
{
public:
    enum StringValue
    {
        evGPS_1C,
        evGPS_2S,
        evGPS_L5,
        evSBAS_1C,
        evGAL_1B,
        evGAL_5X,
        evGLO_1G,
        evGLO_2G
    };
    std::map<std::string, StringValue> mapStringValues_;

    std::string generator_binary;
    std::string p1;
    std::string p2;
    std::string p3;
    std::string p4;
    std::string p5;
    std::string p6;

#if USE_GLOG_AND_GFLAGS
    std::string implementation = FLAGS_trk_test_implementation;
    const int baseband_sampling_freq = FLAGS_fs_gen_sps;
    std::string filename_rinex_obs = FLAGS_filename_rinex_obs;
    std::string filename_raw_data = FLAGS_signal_file;
#else
    std::string implementation = absl::GetFlag(FLAGS_trk_test_implementation);
    const int baseband_sampling_freq = absl::GetFlag(FLAGS_fs_gen_sps);
    std::string filename_rinex_obs = absl::GetFlag(FLAGS_filename_rinex_obs);
    std::string filename_raw_data = absl::GetFlag(FLAGS_signal_file);
#endif

    std::map<int, double> doppler_measurements_map;
    std::map<int, double> code_delay_measurements_map;
    std::map<int, uint64_t> acq_samplestamp_map;

    int configure_generator(double CN0_dBHz, int file_idx);
    int generate_signal();
    std::vector<double> check_results_doppler(arma::vec& true_time_s,
        arma::vec& true_value,
        arma::vec& meas_time_s,
        arma::vec& meas_value,
        double& mean_error,
        double& std_dev_error);
    std::vector<double> check_results_acc_carrier_phase(arma::vec& true_time_s,
        arma::vec& true_value,
        arma::vec& meas_time_s,
        arma::vec& meas_value,
        double& mean_error,
        double& std_dev_error);
    std::vector<double> check_results_codephase(arma::vec& true_time_s,
        arma::vec& true_value,
        arma::vec& meas_time_s,
        arma::vec& meas_value,
        double& mean_error,
        double& std_dev_error);

    TrackingPullInTest()
    {
        factory = std::make_shared<GNSSBlockFactory>();
        config = std::make_shared<InMemoryConfiguration>();
        item_size = sizeof(gr_complex);
        gnss_synchro = Gnss_Synchro();
        mapStringValues_["1C"] = evGPS_1C;
        mapStringValues_["2S"] = evGPS_2S;
        mapStringValues_["L5"] = evGPS_L5;
        mapStringValues_["1B"] = evGAL_1B;
        mapStringValues_["5X"] = evGAL_5X;
        mapStringValues_["1G"] = evGLO_1G;
        mapStringValues_["2G"] = evGLO_2G;
    }

    ~TrackingPullInTest() = default;

    void configure_receiver(double PLL_wide_bw_hz,
        double DLL_wide_bw_hz,
        double PLL_narrow_bw_hz,
        double DLL_narrow_bw_hz,
        int extend_correlation_symbols);

    bool acquire_signal(int SV_ID);

    std::shared_ptr<GNSSBlockFactory> factory;
    std::shared_ptr<InMemoryConfiguration> config;
    Gnss_Synchro gnss_synchro;
    size_t item_size;

    std::shared_ptr<Concurrent_Queue<pmt::pmt_t>> queue;
};


int TrackingPullInTest::configure_generator(double CN0_dBHz, int file_idx)
{
#if USE_GLOG_AND_GFLAGS
    // Configure signal generator
    generator_binary = FLAGS_generator_binary;

    p1 = std::string("-rinex_nav_file=") + FLAGS_rinex_nav_file;
    if (FLAGS_dynamic_position.empty())
        {
            p2 = std::string("-static_position=") + FLAGS_static_position + std::string(",") + std::to_string(FLAGS_duration * 10);
        }
    else
        {
            p2 = std::string("-obs_pos_file=") + std::string(FLAGS_dynamic_position);
        }
    p3 = std::string("-rinex_obs_file=") + FLAGS_filename_rinex_obs;                    // RINEX 2.10 observation file output
    p4 = std::string("-sig_out_file=") + FLAGS_signal_file + std::to_string(file_idx);  // Baseband signal output file. Will be stored in int8_t IQ multiplexed samples
    p5 = std::string("-sampling_freq=") + std::to_string(baseband_sampling_freq);       // Baseband sampling frequency [MSps]
    p6 = std::string("-CN0_dBHz=") + std::to_string(CN0_dBHz);                          // Signal generator CN0
#else
    // Configure signal generator
    generator_binary = absl::GetFlag(FLAGS_generator_binary);

    p1 = std::string("-rinex_nav_file=") + absl::GetFlag(FLAGS_rinex_nav_file);
    if (absl::GetFlag(FLAGS_dynamic_position).empty())
        {
            p2 = std::string("-static_position=") + absl::GetFlag(FLAGS_static_position) + std::string(",") + std::to_string(absl::GetFlag(FLAGS_duration) * 10);
        }
    else
        {
            p2 = std::string("-obs_pos_file=") + std::string(absl::GetFlag(FLAGS_dynamic_position));
        }
    p3 = std::string("-rinex_obs_file=") + absl::GetFlag(FLAGS_filename_rinex_obs);                    // RINEX 2.10 observation file output
    p4 = std::string("-sig_out_file=") + absl::GetFlag(FLAGS_signal_file) + std::to_string(file_idx);  // Baseband signal output file. Will be stored in int8_t IQ multiplexed samples
    p5 = std::string("-sampling_freq=") + std::to_string(baseband_sampling_freq);                      // Baseband sampling frequency [MSps]
    p6 = std::string("-CN0_dBHz=") + std::to_string(CN0_dBHz);                                         // Signal generator CN0
#endif
    return 0;
}


int TrackingPullInTest::generate_signal()
{
    int child_status;

    char* const parmList[] = {&generator_binary[0], &generator_binary[0], &p1[0], &p2[0], &p3[0], &p4[0], &p5[0], &p6[0], nullptr};

    int pid;
    if ((pid = fork()) == -1)
        {
            perror("fork err");
        }
    else if (pid == 0)
        {
            execv(&generator_binary[0], parmList);
            std::cout << "Return not expected. Must be an execv err.\n";
            std::terminate();
        }

    waitpid(pid, &child_status, 0);

    std::cout << "Signal and Observables RINEX and RAW files created.\n";
    return 0;
}


void TrackingPullInTest::configure_receiver(
    double PLL_wide_bw_hz,
    double DLL_wide_bw_hz,
    double PLL_narrow_bw_hz,
    double DLL_narrow_bw_hz,
    int extend_correlation_symbols)
{
    config = std::make_shared<InMemoryConfiguration>();
    config->set_property("Tracking.dump", "true");
    config->set_property("Tracking.dump_filename", "./tracking_ch_");
    config->set_property("Tracking.implementation", implementation);
    config->set_property("Tracking.item_type", "gr_complex");
    config->set_property("Tracking.pll_bw_hz", std::to_string(PLL_wide_bw_hz));
    config->set_property("Tracking.dll_bw_hz", std::to_string(DLL_wide_bw_hz));
    config->set_property("Tracking.extend_correlation_symbols", std::to_string(extend_correlation_symbols));
    config->set_property("Tracking.pll_bw_narrow_hz", std::to_string(PLL_narrow_bw_hz));
    config->set_property("Tracking.dll_bw_narrow_hz", std::to_string(DLL_narrow_bw_hz));
#if USE_GLOG_AND_GFLAGS
    gnss_synchro.PRN = FLAGS_test_satellite_PRN;
#else
    gnss_synchro.PRN = absl::GetFlag(FLAGS_test_satellite_PRN);
#endif
    gnss_synchro.Channel_ID = 0;
    config->set_property("GNSS-SDR.internal_fs_sps", std::to_string(baseband_sampling_freq));

    std::string System_and_Signal;
    if (implementation == "GPS_L1_CA_DLL_PLL_Tracking")
        {
            gnss_synchro.System = 'G';
            std::string signal = "1C";
            System_and_Signal = "GPS L1 CA";
            signal.copy(gnss_synchro.Signal, 2, 0);
            config->set_property("Tracking.early_late_space_chips", "0.5");
            config->set_property("Tracking.early_late_space_narrow_chips", "0.5");
        }
    else if (implementation == "Galileo_E1_DLL_PLL_VEML_Tracking")
        {
            gnss_synchro.System = 'E';
            std::string signal = "1B";
            System_and_Signal = "Galileo E1B";
            signal.copy(gnss_synchro.Signal, 2, 0);
            config->set_property("Tracking.early_late_space_chips", "0.15");
            config->set_property("Tracking.very_early_late_space_chips", "0.6");
            config->set_property("Tracking.early_late_space_narrow_chips", "0.15");
            config->set_property("Tracking.very_early_late_space_narrow_chips", "0.6");
            config->set_property("Tracking.track_pilot", "true");
        }
    else if (implementation == "GPS_L2_M_DLL_PLL_Tracking")
        {
            gnss_synchro.System = 'G';
            std::string signal = "2S";
            System_and_Signal = "GPS L2CM";
            signal.copy(gnss_synchro.Signal, 2, 0);
            config->set_property("Tracking.early_late_space_chips", "0.5");
            config->set_property("Tracking.track_pilot", "true");
        }
    else if (implementation == "Galileo_E5a_DLL_PLL_Tracking" or implementation == "Galileo_E5a_DLL_PLL_Tracking_b")
        {
            gnss_synchro.System = 'E';
            std::string signal = "5X";
            System_and_Signal = "Galileo E5a";
            signal.copy(gnss_synchro.Signal, 2, 0);
            if (implementation == "Galileo_E5a_DLL_PLL_Tracking_b")
                {
                    config->supersede_property("Tracking.implementation", std::string("Galileo_E5a_DLL_PLL_Tracking"));
                }
            config->set_property("Tracking.early_late_space_chips", "0.5");
            config->set_property("Tracking.track_pilot", "true");
            config->set_property("Tracking.order", "2");
        }
    else if (implementation == "GPS_L5_DLL_PLL_Tracking")
        {
            gnss_synchro.System = 'G';
            std::string signal = "L5";
            System_and_Signal = "GPS L5I";
            signal.copy(gnss_synchro.Signal, 2, 0);
            config->set_property("Tracking.early_late_space_chips", "0.5");
            config->set_property("Tracking.track_pilot", "true");
            config->set_property("Tracking.order", "2");
        }
    else
        {
            std::cout << "The test can not run with the selected tracking implementation\n ";
            throw(std::exception());
        }

    std::cout << "*****************************************\n";
    std::cout << "*** Tracking configuration parameters ***\n";
    std::cout << "*****************************************\n";
    std::cout << "Signal: " << System_and_Signal << "\n";
    std::cout << "implementation: " << config->property("Tracking.implementation", std::string("undefined")) << " \n";
    std::cout << "pll_bw_hz: " << config->property("Tracking.pll_bw_hz", 0.0) << " Hz\n";
    std::cout << "dll_bw_hz: " << config->property("Tracking.dll_bw_hz", 0.0) << " Hz\n";
    std::cout << "pll_bw_narrow_hz: " << config->property("Tracking.pll_bw_narrow_hz", 0.0) << " Hz\n";
    std::cout << "dll_bw_narrow_hz: " << config->property("Tracking.dll_bw_narrow_hz", 0.0) << " Hz\n";
    std::cout << "extend_correlation_symbols: " << config->property("Tracking.extend_correlation_symbols", 0) << " Symbols\n";
    std::cout << "*****************************************\n";
    std::cout << "*****************************************\n";
}


bool TrackingPullInTest::acquire_signal(int SV_ID)
{
    // 1. Setup GNU Radio flowgraph (file_source -> Acquisition_10m)
    gr::top_block_sptr top_block_acq;
    top_block_acq = gr::make_top_block("Acquisition test");

    // Satellite signal definition
    Gnss_Synchro tmp_gnss_synchro;
    tmp_gnss_synchro.Channel_ID = 0;

    config = std::make_shared<InMemoryConfiguration>();
    config->set_property("GNSS-SDR.internal_fs_sps", std::to_string(baseband_sampling_freq));
// Enable automatic resampler for the acquisition, if required
#if USE_GLOG_AND_GFLAGS
    if (FLAGS_use_acquisition_resampler == true)
#else
    if (absl::GetFlag(FLAGS_use_acquisition_resampler) == true)
#endif
        {
            config->set_property("GNSS-SDR.use_acquisition_resampler", "true");
        }
    config->set_property("Acquisition.blocking_on_standby", "true");
    config->set_property("Acquisition.blocking", "true");
    config->set_property("Acquisition.dump", "false");
    config->set_property("Acquisition.dump_filename", "./data/acquisition.dat");

    std::shared_ptr<AcquisitionInterface> acquisition;

    std::string System_and_Signal;
    std::string signal;
    // create the correspondign acquisition block according to the desired tracking signal
    if (implementation == "GPS_L1_CA_DLL_PLL_Tracking")
        {
            tmp_gnss_synchro.System = 'G';
            signal = "1C";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "GPS L1 CA";
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            // acquisition = std::make_shared<GpsL1CaPcpsAcquisitionFineDoppler>(config.get(), "Acquisition", 1, 0);
            acquisition = std::make_shared<GpsL1CaPcpsAcquisition>(config.get(), "Acquisition", 1, 0);
        }
    else if (implementation == "Galileo_E1_DLL_PLL_VEML_Tracking")
        {
            tmp_gnss_synchro.System = 'E';
            signal = "1B";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "Galileo E1B";
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            acquisition = std::make_shared<GalileoE1PcpsAmbiguousAcquisition>(config.get(), "Acquisition", 1, 0);
        }
    else if (implementation == "GPS_L2_M_DLL_PLL_Tracking")
        {
            tmp_gnss_synchro.System = 'G';
            signal = "2S";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "GPS L2CM";
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            acquisition = std::make_shared<GpsL2MPcpsAcquisition>(config.get(), "Acquisition", 1, 0);
        }
    else if (implementation == "Galileo_E5a_DLL_PLL_Tracking_b")
        {
            tmp_gnss_synchro.System = 'E';
            signal = "5X";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "Galileo E5a";
            config->set_property("Acquisition_5X.coherent_integration_time_ms", "1");
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            config->set_property("Acquisition.CAF_window_hz", "0");  // **Only for E5a** Resolves doppler ambiguity averaging the specified BW in the winner code delay. If set to 0 CAF filter is deactivated. Recommended value 3000 Hz
            config->set_property("Acquisition.Zero_padding", "0");   // **Only for E5a** Avoids power loss and doppler ambiguity in bit transitions by correlating one code with twice the input data length, ensuring that at least one full code is present without transitions. If set to 1 it is ON, if set to 0 it is OFF.
            config->set_property("Acquisition.bit_transition_flag", "false");
            acquisition = std::make_shared<GalileoE5aNoncoherentIQAcquisitionCaf>(config.get(), "Acquisition", 1, 0);
        }

    else if (implementation == "Galileo_E5a_DLL_PLL_Tracking")
        {
            tmp_gnss_synchro.System = 'E';
            signal = "5X";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "Galileo E5a";
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            acquisition = std::make_shared<GalileoE5aPcpsAcquisition>(config.get(), "Acquisition", 1, 0);
        }
    else if (implementation == "GPS_L5_DLL_PLL_Tracking")
        {
            tmp_gnss_synchro.System = 'G';
            signal = "L5";
            const char* str = signal.c_str();                                  // get a C style null terminated string
            std::memcpy(static_cast<void*>(tmp_gnss_synchro.Signal), str, 3);  // copy string into synchro char array: 2 char + null
            tmp_gnss_synchro.PRN = SV_ID;
            System_and_Signal = "GPS L5I";
#if USE_GLOG_AND_GFLAGS
            config->set_property("Acquisition.max_dwells", std::to_string(FLAGS_external_signal_acquisition_dwells));
#else
            config->set_property("Acquisition.max_dwells", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_dwells)));
#endif
            acquisition = std::make_shared<GpsL5iPcpsAcquisition>(config.get(), "Acquisition", 1, 0);
        }
    else
        {
            std::cout << "The test can not run with the selected tracking implementation\n ";
            throw(std::exception());
        }

    acquisition->set_gnss_synchro(&tmp_gnss_synchro);
    acquisition->set_channel(0);
#if USE_GLOG_AND_GFLAGS
    acquisition->set_doppler_max(config->property("Acquisition.doppler_max", FLAGS_external_signal_acquisition_doppler_max_hz));
    acquisition->set_doppler_step(config->property("Acquisition.doppler_step", FLAGS_external_signal_acquisition_doppler_step_hz));
    acquisition->set_threshold(config->property("Acquisition.threshold", FLAGS_external_signal_acquisition_threshold));
#else
    acquisition->set_doppler_max(config->property("Acquisition.doppler_max", absl::GetFlag(FLAGS_external_signal_acquisition_doppler_max_hz)));
    acquisition->set_doppler_step(config->property("Acquisition.doppler_step", absl::GetFlag(FLAGS_external_signal_acquisition_doppler_step_hz)));
    acquisition->set_threshold(config->property("Acquisition.threshold", absl::GetFlag(FLAGS_external_signal_acquisition_threshold)));
#endif
    acquisition->init();
    acquisition->set_local_code();
    acquisition->set_state(1);  // Ensure that acquisition starts at the first sample
    acquisition->connect(top_block_acq);

    gr::blocks::file_source::sptr file_source;
#if USE_GLOG_AND_GFLAGS
    std::string file = FLAGS_signal_file;
#else
    std::string file = absl::GetFlag(FLAGS_signal_file);
#endif
    const char* file_name = file.c_str();
    file_source = gr::blocks::file_source::make(sizeof(int8_t), file_name, false);
#if USE_GLOG_AND_GFLAGS
    file_source->seek(2 * FLAGS_skip_samples, SEEK_SET);  // skip head. ibyte, two bytes per complex sample
#else
    file_source->seek(2 * absl::GetFlag(FLAGS_skip_samples), SEEK_SET);  // skip head. ibyte, two bytes per complex sample
#endif
    gr::blocks::interleaved_char_to_complex::sptr gr_interleaved_char_to_complex = gr::blocks::interleaved_char_to_complex::make();
    // gr::blocks::head::sptr head_samples = gr::blocks::head::make(sizeof(gr_complex), baseband_sampling_freq * FLAGS_duration);

    top_block_acq->connect(file_source, 0, gr_interleaved_char_to_complex, 0);

// Enable automatic resampler for the acquisition, if required
#if USE_GLOG_AND_GFLAGS
    if (FLAGS_use_acquisition_resampler == true)
#else
    if (absl::GetFlag(FLAGS_use_acquisition_resampler) == true)
#endif
        {
            // create acquisition resamplers if required
            double resampler_ratio = 1.0;

            double opt_fs = baseband_sampling_freq;
            // find the signal associated to this channel
            switch (mapStringValues_[signal])
                {
                case evGPS_1C:
                    opt_fs = GPS_L1_CA_OPT_ACQ_FS_SPS;
                    break;
                case evGPS_2S:
                    opt_fs = GPS_L2C_OPT_ACQ_FS_SPS;
                    break;
                case evGPS_L5:
                    opt_fs = GPS_L5_OPT_ACQ_FS_SPS;
                    break;
                case evSBAS_1C:
                    opt_fs = GPS_L1_CA_OPT_ACQ_FS_SPS;
                    break;
                case evGAL_1B:
                    opt_fs = GALILEO_E1_OPT_ACQ_FS_SPS;
                    break;
                case evGAL_5X:
                    opt_fs = GALILEO_E5A_OPT_ACQ_FS_SPS;
                    break;
                case evGLO_1G:
                    opt_fs = baseband_sampling_freq;
                    break;
                case evGLO_2G:
                    opt_fs = baseband_sampling_freq;
                    break;
                }
            if (opt_fs < baseband_sampling_freq)
                {
                    resampler_ratio = baseband_sampling_freq / opt_fs;
                    int decimation = floor(resampler_ratio);
                    while (baseband_sampling_freq % decimation > 0)
                        {
                            decimation--;
                        };
                    double acq_fs = baseband_sampling_freq / decimation;

                    if (decimation > 1)
                        {
                            // create a FIR low pass filter
                            std::vector<float> taps;
                            taps = gr::filter::firdes::low_pass(1.0,
                                baseband_sampling_freq,
                                acq_fs / 2.1,
                                acq_fs / 10);
                            std::cout << "Enabled decimation low pass filter with " << taps.size() << " taps and decimation factor of " << decimation << '\n';
                            acquisition->set_resampler_latency((taps.size() - 1) / 2);
                            gr::basic_block_sptr fir_filter_ccf_ = gr::filter::fir_filter_ccf::make(decimation, taps);
                            top_block_acq->connect(gr_interleaved_char_to_complex, 0, fir_filter_ccf_, 0);
                            top_block_acq->connect(fir_filter_ccf_, 0, acquisition->get_left_block(), 0);
                        }
                    else
                        {
                            std::cout << "Disabled acquisition resampler because the input sampling frequency is too low\n";
                            top_block_acq->connect(gr_interleaved_char_to_complex, 0, acquisition->get_left_block(), 0);
                        }
                }
            else
                {
                    std::cout << "Disabled acquisition resampler because the input sampling frequency is too low\n";
                    top_block_acq->connect(gr_interleaved_char_to_complex, 0, acquisition->get_left_block(), 0);
                }
        }
    else
        {
            top_block_acq->connect(gr_interleaved_char_to_complex, 0, acquisition->get_left_block(), 0);
            // top_block_acq->connect(head_samples, 0, acquisition->get_left_block(), 0);
        }
    gnss_shared_ptr<Acquisition_msg_rx> msg_rx;
    try
        {
            msg_rx = Acquisition_msg_rx_make();
        }
    catch (const std::exception& e)
        {
            std::cout << "Failure connecting the message port system: " << e.what() << '\n';
            exit(0);
        }

    msg_rx->top_block = top_block_acq;
    top_block_acq->msg_connect(acquisition->get_right_block(), pmt::mp("events"), msg_rx, pmt::mp("events"));

    // 5. Run the flowgraph
    // Get visible GPS satellites (positive acquisitions with Doppler measurements)
    // record startup time
    std::chrono::time_point<std::chrono::system_clock> start, end;
    std::chrono::duration<double> elapsed_seconds;
    start = std::chrono::system_clock::now();

    bool start_msg = true;

    doppler_measurements_map.clear();
    code_delay_measurements_map.clear();
    acq_samplestamp_map.clear();

    unsigned int MAX_PRN_IDX = 0;

    switch (tmp_gnss_synchro.System)
        {
        case 'G':
            MAX_PRN_IDX = 33;
            break;
        case 'E':
            MAX_PRN_IDX = 37;
            break;
        default:
            MAX_PRN_IDX = 33;
        }

    for (unsigned int PRN = 1; PRN < MAX_PRN_IDX; PRN++)
        {
            tmp_gnss_synchro.PRN = PRN;
            acquisition->set_gnss_synchro(&tmp_gnss_synchro);
            acquisition->init();
            acquisition->set_local_code();
            acquisition->reset();
            acquisition->set_state(1);
            msg_rx->rx_message = 0;
            top_block_acq->run();
            if (start_msg == true)
                {
#if USE_GLOG_AND_GFLAGS
                    std::cout << "Reading external signal file: " << FLAGS_signal_file << '\n';
#else
                    std::cout << "Reading external signal file: " << absl::GetFlag(FLAGS_signal_file) << '\n';
#endif
                    std::cout << "Searching for " << System_and_Signal << " Satellites...\n";
                    std::cout << "[";
                    start_msg = false;
                }
            while (msg_rx->rx_message == 0)
                {
                    usleep(100000);
                }
            if (msg_rx->rx_message == 1)
                {
                    std::cout << " " << PRN << " ";
                    doppler_measurements_map.insert(std::pair<int, double>(PRN, tmp_gnss_synchro.Acq_doppler_hz));
                    code_delay_measurements_map.insert(std::pair<int, double>(PRN, tmp_gnss_synchro.Acq_delay_samples));
                    acq_samplestamp_map.insert(std::pair<int, double>(PRN, tmp_gnss_synchro.Acq_samplestamp_samples));
                }
            else
                {
                    std::cout << " . ";
                }
            top_block_acq->stop();
#if USE_GLOG_AND_GFLAGS
            file_source->seek(2 * FLAGS_skip_samples, SEEK_SET);  // skip head. ibyte, two bytes per complex sample
#else
            file_source->seek(2 * absl::GetFlag(FLAGS_skip_samples), SEEK_SET);  // skip head. ibyte, two bytes per complex sample
#endif
            std::cout.flush();
        }
    std::cout << "]\n";
    std::cout << "-------------------------------------------\n";

    for (auto& x : doppler_measurements_map)
        {
            std::cout << "DETECTED SATELLITE " << System_and_Signal << " PRN: " << x.first << " with Doppler: " << x.second << " [Hz], code phase: " << code_delay_measurements_map.at(x.first) << " [samples] at signal SampleStamp " << acq_samplestamp_map.at(x.first) << "\n";
        }

    // report the elapsed time
    end = std::chrono::system_clock::now();
    elapsed_seconds = end - start;
    std::cout << "Total signal acquisition run time "
              << elapsed_seconds.count()
              << " [seconds]\n";
    return true;
}


TEST_F(TrackingPullInTest, ValidationOfResults)
{
    // *************************************************
    // ***** STEP 1: Prepare the parameters sweep ******
    // *************************************************
    std::vector<double> acq_doppler_error_hz_values;
    std::vector<std::vector<double>> acq_delay_error_chips_values;  // vector of vector
#if USE_GLOG_AND_GFLAGS
    for (double doppler_hz = FLAGS_acq_Doppler_error_hz_start; doppler_hz >= FLAGS_acq_Doppler_error_hz_stop; doppler_hz = doppler_hz + FLAGS_acq_Doppler_error_hz_step)
#else
    for (double doppler_hz = absl::GetFlag(FLAGS_acq_Doppler_error_hz_start); doppler_hz >= absl::GetFlag(FLAGS_acq_Doppler_error_hz_stop); doppler_hz = doppler_hz + absl::GetFlag(FLAGS_acq_Doppler_error_hz_step))
#endif

        {
            acq_doppler_error_hz_values.push_back(doppler_hz);
            std::vector<double> tmp_vector;
// Code Delay Sweep
#if USE_GLOG_AND_GFLAGS
            for (double code_delay_chips = FLAGS_acq_Delay_error_chips_start; code_delay_chips >= FLAGS_acq_Delay_error_chips_stop; code_delay_chips = code_delay_chips + FLAGS_acq_Delay_error_chips_step)
#else
            for (double code_delay_chips = absl::GetFlag(FLAGS_acq_Delay_error_chips_start); code_delay_chips >= absl::GetFlag(FLAGS_acq_Delay_error_chips_stop); code_delay_chips = code_delay_chips + absl::GetFlag(FLAGS_acq_Delay_error_chips_step))
#endif
                {
                    tmp_vector.push_back(code_delay_chips);
                }
            acq_delay_error_chips_values.push_back(tmp_vector);
        }

    // ***********************************************************
    // ***** STEP 2: Generate the input signal (if required) *****
    // ***********************************************************
    std::vector<double> generator_CN0_values;
#if USE_GLOG_AND_GFLAGS
    if (FLAGS_enable_external_signal_file)
#else
    if (absl::GetFlag(FLAGS_enable_external_signal_file))
#endif
        {
            generator_CN0_values.push_back(999);  // an external input signal capture is selected, no CN0 information available
        }
    else
        {
#if USE_GLOG_AND_GFLAGS
            if (FLAGS_CN0_dBHz_start == FLAGS_CN0_dBHz_stop)
                {
                    generator_CN0_values.push_back(FLAGS_CN0_dBHz_start);
                }
            else
                {
                    for (double cn0 = FLAGS_CN0_dBHz_start; cn0 > FLAGS_CN0_dBHz_stop; cn0 = cn0 - FLAGS_CN0_dB_step)
                        {
                            generator_CN0_values.push_back(cn0);
                        }
                }
#else
            if (absl::GetFlag(FLAGS_CN0_dBHz_start) == absl::GetFlag(FLAGS_CN0_dBHz_stop))
                {
                    generator_CN0_values.push_back(absl::GetFlag(FLAGS_CN0_dBHz_start));
                }
            else
                {
                    for (double cn0 = absl::GetFlag(FLAGS_CN0_dBHz_start); cn0 > absl::GetFlag(FLAGS_CN0_dBHz_stop); cn0 = cn0 - absl::GetFlag(FLAGS_CN0_dB_step))
                        {
                            generator_CN0_values.push_back(cn0);
                        }
                }
#endif
        }

        // use generator or use an external capture file

#if USE_GLOG_AND_GFLAGS
    if (FLAGS_enable_external_signal_file)
#else
    if (absl::GetFlag(FLAGS_enable_external_signal_file))
#endif
        {
#if USE_GLOG_AND_GFLAGS
            // create and configure an acquisition block and perform an acquisition to obtain the synchronization parameters
            ASSERT_EQ(acquire_signal(FLAGS_test_satellite_PRN), true);
            bool found_satellite = doppler_measurements_map.find(FLAGS_test_satellite_PRN) != doppler_measurements_map.end();
            EXPECT_TRUE(found_satellite) << "Error: satellite SV: " << FLAGS_test_satellite_PRN << " is not acquired";
#else
            ASSERT_EQ(acquire_signal(absl::GetFlag(FLAGS_test_satellite_PRN)), true);
            bool found_satellite = doppler_measurements_map.find(absl::GetFlag(FLAGS_test_satellite_PRN)) != doppler_measurements_map.end();
            EXPECT_TRUE(found_satellite) << "Error: satellite SV: " << absl::GetFlag(FLAGS_test_satellite_PRN) << " is not acquired";
#endif
            if (!found_satellite)
                {
                    return;
                }
        }
    else
        {
            for (unsigned int current_cn0_idx = 0; current_cn0_idx < generator_CN0_values.size(); current_cn0_idx++)
                {
                    // Configure the signal generator
                    configure_generator(generator_CN0_values.at(current_cn0_idx), current_cn0_idx);
                    // Generate signal raw signal samples and observations RINEX file
#if USE_GLOG_AND_GFLAGS
                    if (FLAGS_disable_generator == false)
#else
                    if (absl::GetFlag(FLAGS_disable_generator) == false)
#endif
                        {
                            generate_signal();
                        }
                }
        }

#if USE_GLOG_AND_GFLAGS
    configure_receiver(FLAGS_PLL_bw_hz_start,
        FLAGS_DLL_bw_hz_start,
        FLAGS_PLL_narrow_bw_hz,
        FLAGS_DLL_narrow_bw_hz,
        FLAGS_extend_correlation_symbols);
#else
    configure_receiver(absl::GetFlag(FLAGS_PLL_bw_hz_start),
        absl::GetFlag(FLAGS_DLL_bw_hz_start),
        absl::GetFlag(FLAGS_PLL_narrow_bw_hz),
        absl::GetFlag(FLAGS_DLL_narrow_bw_hz),
        absl::GetFlag(FLAGS_extend_correlation_symbols));
#endif

    // ******************************************************************************************
    // ***** Obtain the initial signal sinchronization parameters (emulating an acquisition) ****
    // ******************************************************************************************
    int test_satellite_PRN = 0;
    double true_acq_doppler_hz = 0.0;
    double true_acq_delay_samples = 0.0;
    uint64_t acq_samplestamp_samples = 0;

    Tracking_True_Obs_Reader true_obs_data;
#if USE_GLOG_AND_GFLAGS
    if (!FLAGS_enable_external_signal_file)
        {
            test_satellite_PRN = FLAGS_test_satellite_PRN;
#else
    if (!absl::GetFlag(FLAGS_enable_external_signal_file))
        {
            test_satellite_PRN = absl::GetFlag(FLAGS_test_satellite_PRN);
#endif
            std::string true_obs_file = std::string("./gps_l1_ca_obs_prn");
            true_obs_file.append(std::to_string(test_satellite_PRN));
            true_obs_file.append(".dat");
            true_obs_data.close_obs_file();
            ASSERT_EQ(true_obs_data.open_obs_file(true_obs_file), true) << "Failure opening true observables file";
            // load acquisition data based on the first epoch of the true observations
            ASSERT_EQ(true_obs_data.read_binary_obs(), true)
                << "Failure reading true tracking dump file.\n"
#if USE_GLOG_AND_GFLAGS
                << "Maybe sat PRN #" + std::to_string(FLAGS_test_satellite_PRN) +
#else
                << "Maybe sat PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) +
#endif
                       " is not available?";
            std::cout << "Testing satellite PRN=" << test_satellite_PRN << '\n';
            std::cout << "True Initial Doppler " << true_obs_data.doppler_l1_hz << " [Hz], true Initial code delay [Chips]=" << true_obs_data.prn_delay_chips << "[Chips]\n";
            true_acq_doppler_hz = true_obs_data.doppler_l1_hz;
            true_acq_delay_samples = (GPS_L1_CA_CODE_LENGTH_CHIPS - true_obs_data.prn_delay_chips / GPS_L1_CA_CODE_LENGTH_CHIPS) * static_cast<double>(baseband_sampling_freq) * GPS_L1_CA_CODE_PERIOD_S;
            acq_samplestamp_samples = 0;
        }
    else
        {
#if USE_GLOG_AND_GFLAGS
            true_acq_doppler_hz = doppler_measurements_map.find(FLAGS_test_satellite_PRN)->second;
            true_acq_delay_samples = code_delay_measurements_map.find(FLAGS_test_satellite_PRN)->second;
#else
            true_acq_doppler_hz = doppler_measurements_map.find(absl::GetFlag(FLAGS_test_satellite_PRN))->second;
            true_acq_delay_samples = code_delay_measurements_map.find(absl::GetFlag(FLAGS_test_satellite_PRN))->second;
#endif
            acq_samplestamp_samples = 0;
            std::cout << "Estimated Initial Doppler " << true_acq_doppler_hz
                      << " [Hz], estimated Initial code delay " << true_acq_delay_samples << " [Samples]"
#if USE_GLOG_AND_GFLAGS
                      << " Acquisition SampleStamp is " << acq_samplestamp_map.find(FLAGS_test_satellite_PRN)->second << '\n';
#else
                      << " Acquisition SampleStamp is " << acq_samplestamp_map.find(absl::GetFlag(FLAGS_test_satellite_PRN))->second << '\n';
#endif
        }

    // create the msg queue for valve
    queue = std::make_shared<Concurrent_Queue<pmt::pmt_t>>();
#if USE_GLOG_AND_GFLAGS
    long long int acq_to_trk_delay_samples = ceil(static_cast<double>(FLAGS_fs_gen_sps) * FLAGS_acq_to_trk_delay_s);
#else
    long long int acq_to_trk_delay_samples = ceil(static_cast<double>(absl::GetFlag(FLAGS_fs_gen_sps)) * absl::GetFlag(FLAGS_acq_to_trk_delay_s));
#endif
    auto resetable_valve_ = gnss_sdr_make_valve(sizeof(gr_complex), acq_to_trk_delay_samples, queue.get(), false);

    // CN0 LOOP
    std::vector<std::vector<double>> pull_in_results_v_v;

    for (unsigned int current_cn0_idx = 0; current_cn0_idx < generator_CN0_values.size(); current_cn0_idx++)
        {
            std::vector<double> pull_in_results_v;
            for (unsigned int current_acq_doppler_error_idx = 0; current_acq_doppler_error_idx < acq_doppler_error_hz_values.size(); current_acq_doppler_error_idx++)
                {
                    for (unsigned int current_acq_code_error_idx = 0; current_acq_code_error_idx < acq_delay_error_chips_values.at(current_acq_doppler_error_idx).size(); current_acq_code_error_idx++)
                        {
                            gnss_synchro.Acq_samplestamp_samples = acq_samplestamp_samples;
                            // simulate a Doppler error in acquisition
                            gnss_synchro.Acq_doppler_hz = true_acq_doppler_hz + acq_doppler_error_hz_values.at(current_acq_doppler_error_idx);
                            // simulate Code Delay error in acquisition
                            gnss_synchro.Acq_delay_samples = true_acq_delay_samples + (acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx) / GPS_L1_CA_CODE_RATE_CPS) * static_cast<double>(baseband_sampling_freq);

                            // create flowgraph
                            auto top_block_trk = gr::make_top_block("Tracking test");
                            std::shared_ptr<GNSSBlockInterface> trk_ = factory->GetBlock(config.get(), "Tracking", 1, 1);
                            std::shared_ptr<TrackingInterface> tracking = std::dynamic_pointer_cast<TrackingInterface>(trk_);
                            auto msg_rx = TrackingPullInTest_msg_rx_make();

                            ASSERT_NO_THROW({
                                tracking->set_channel(gnss_synchro.Channel_ID);
                            }) << "Failure setting channel.";

                            ASSERT_NO_THROW({
                                tracking->set_gnss_synchro(&gnss_synchro);
                            }) << "Failure setting gnss_synchro.";

                            ASSERT_NO_THROW({
                                tracking->connect(top_block_trk);
                            }) << "Failure connecting tracking to the top_block.";

                            std::string file;
                            ASSERT_NO_THROW({
#if USE_GLOG_AND_GFLAGS
                                if (!FLAGS_enable_external_signal_file)
#else
                                if (!absl::GetFlag(FLAGS_enable_external_signal_file))
#endif
                                    {
                                        file = "./" + filename_raw_data + std::to_string(current_cn0_idx);
                                    }
                                else
                                    {
#if USE_GLOG_AND_GFLAGS
                                        file = FLAGS_signal_file;
#else
                                        file = absl::GetFlag(FLAGS_signal_file);
#endif
                                    }
                                const char* file_name = file.c_str();
                                gr::blocks::file_source::sptr file_source = gr::blocks::file_source::make(sizeof(int8_t), file_name, false);
                                gr::blocks::interleaved_char_to_complex::sptr gr_interleaved_char_to_complex = gr::blocks::interleaved_char_to_complex::make();
                                gr::blocks::null_sink::sptr sink = gr::blocks::null_sink::make(sizeof(Gnss_Synchro));
#if USE_GLOG_AND_GFLAGS
                                gr::blocks::head::sptr head_samples = gr::blocks::head::make(sizeof(gr_complex), baseband_sampling_freq * FLAGS_duration);
#else
                                gr::blocks::head::sptr head_samples = gr::blocks::head::make(sizeof(gr_complex), baseband_sampling_freq * absl::GetFlag(FLAGS_duration));
#endif
                                top_block_trk->connect(file_source, 0, gr_interleaved_char_to_complex, 0);
                                top_block_trk->connect(gr_interleaved_char_to_complex, 0, head_samples, 0);
                                if (acq_to_trk_delay_samples > 0)
                                    {
                                        top_block_trk->connect(head_samples, 0, resetable_valve_, 0);
                                        top_block_trk->connect(resetable_valve_, 0, tracking->get_left_block(), 0);
                                    }
                                else
                                    {
                                        top_block_trk->connect(head_samples, 0, tracking->get_left_block(), 0);
                                    }
                                top_block_trk->connect(tracking->get_right_block(), 0, sink, 0);
                                top_block_trk->msg_connect(tracking->get_right_block(), pmt::mp("events"), msg_rx, pmt::mp("events"));
#if USE_GLOG_AND_GFLAGS
                                file_source->seek(2 * FLAGS_skip_samples, 0);  // skip head. ibyte, two bytes per complex sample
#else
                                file_source->seek(2 * absl::GetFlag(FLAGS_skip_samples), 0);  // skip head. ibyte, two bytes per complex sample
#endif
                            }) << "Failure connecting the blocks of tracking test.";

                            // ********************************************************************
                            // ***** STEP 5: Perform the signal tracking and read the results *****
                            // ********************************************************************
                            std::cout << "--- START TRACKING WITH PULL-IN ERROR: " << acq_doppler_error_hz_values.at(current_acq_doppler_error_idx) << " [Hz] and " << acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx) << " [Chips] ---\n";
                            std::chrono::time_point<std::chrono::system_clock> start, end;
                            if (acq_to_trk_delay_samples > 0)
                                {
                                    EXPECT_NO_THROW({
                                        start = std::chrono::system_clock::now();
#if USE_GLOG_AND_GFLAGS
                                        std::cout << "--- SIMULATING A PULL-IN DELAY OF " << FLAGS_acq_to_trk_delay_s << " SECONDS ---\n";
#else
                                        std::cout << "--- SIMULATING A PULL-IN DELAY OF " << absl::GetFlag(FLAGS_acq_to_trk_delay_s) << " SECONDS ---\n";
#endif
                                        top_block_trk->start();
                                        std::cout << " Waiting for valve...\n";
                                        // wait the valve message indicating the circulation of the amount of samples of the delay
                                        pmt::pmt_t msg;
                                        queue->wait_and_pop(msg);
                                        std::cout << " Starting tracking...\n";
                                        tracking->start_tracking();
                                        resetable_valve_->open_valve();
                                        std::cout << " Waiting flowgraph..\n";
                                        top_block_trk->wait();
                                        end = std::chrono::system_clock::now();
                                    }) << "Failure running the top_block.";
                                }
                            else
                                {
                                    tracking->start_tracking();
                                    EXPECT_NO_THROW({
                                        start = std::chrono::system_clock::now();
                                        top_block_trk->run();  // Start threads and wait
                                        end = std::chrono::system_clock::now();
                                    }) << "Failure running the top_block.";
                                }

                            std::chrono::duration<double> elapsed_seconds = end - start;
                            std::cout << "Signal tracking completed in " << elapsed_seconds.count() << " seconds\n";

                            pull_in_results_v.push_back(msg_rx->rx_message != 3);  // save last asynchronous tracking message in order to detect a loss of lock

// ********************************
// ***** STEP 7: Plot results *****
// ********************************
#if USE_GLOG_AND_GFLAGS
                            if (FLAGS_plot_detail_level >= 2 and FLAGS_show_plots)
#else
                            if (absl::GetFlag(FLAGS_plot_detail_level) >= 2 and absl::GetFlag(FLAGS_show_plots))
#endif
                                {
                                    // load the measured values
                                    Tracking_Dump_Reader trk_dump;
                                    ASSERT_EQ(trk_dump.open_obs_file(std::string("./tracking_ch_0.dat")), true)
                                        << "Failure opening tracking dump file";

                                    int64_t n_measured_epochs = trk_dump.num_epochs();
                                    // todo: use vectors instead
                                    arma::vec trk_timestamp_s = arma::zeros(n_measured_epochs, 1);
                                    arma::vec trk_acc_carrier_phase_cycles = arma::zeros(n_measured_epochs, 1);
                                    arma::vec trk_Doppler_Hz = arma::zeros(n_measured_epochs, 1);
                                    arma::vec trk_prn_delay_chips = arma::zeros(n_measured_epochs, 1);
                                    std::vector<double> timestamp_s;
                                    std::vector<double> prompt;
                                    std::vector<double> early;
                                    std::vector<double> late;
                                    std::vector<double> v_early;
                                    std::vector<double> v_late;
                                    std::vector<double> promptI;
                                    std::vector<double> promptQ;
                                    std::vector<double> CN0_dBHz;
                                    std::vector<double> Doppler;
                                    int64_t epoch_counter = 0;
                                    while (trk_dump.read_binary_obs())
                                        {
                                            trk_timestamp_s(epoch_counter) = static_cast<double>(trk_dump.PRN_start_sample_count) / static_cast<double>(baseband_sampling_freq);
                                            trk_acc_carrier_phase_cycles(epoch_counter) = trk_dump.acc_carrier_phase_rad / TWO_PI;
                                            trk_Doppler_Hz(epoch_counter) = trk_dump.carrier_doppler_hz;
                                            double delay_chips = GPS_L1_CA_CODE_LENGTH_CHIPS - GPS_L1_CA_CODE_LENGTH_CHIPS * (fmod((static_cast<double>(trk_dump.PRN_start_sample_count) + trk_dump.aux1) / static_cast<double>(baseband_sampling_freq), 1.0e-3) / 1.0e-3);

                                            trk_prn_delay_chips(epoch_counter) = delay_chips;

                                            timestamp_s.push_back(trk_timestamp_s(epoch_counter));
                                            prompt.push_back(trk_dump.abs_P);
                                            early.push_back(trk_dump.abs_E);
                                            late.push_back(trk_dump.abs_L);
                                            v_early.push_back(trk_dump.abs_VE);
                                            v_late.push_back(trk_dump.abs_VL);
                                            promptI.push_back(trk_dump.prompt_I);
                                            promptQ.push_back(trk_dump.prompt_Q);
                                            CN0_dBHz.push_back(trk_dump.CN0_SNV_dB_Hz);
                                            Doppler.push_back(trk_dump.carrier_doppler_hz);
                                            epoch_counter++;
                                        }
#if USE_GLOG_AND_GFLAGS
                                    const std::string gnuplot_executable(FLAGS_gnuplot_executable);
#else
                                    const std::string gnuplot_executable(absl::GetFlag(FLAGS_gnuplot_executable));
#endif
                                    if (gnuplot_executable.empty())
                                        {
                                            std::cout << "WARNING: Although the flag show_plots has been set to TRUE,\n";
                                            std::cout << "gnuplot has not been found in your system.\n";
                                            std::cout << "Test results will not be plotted.\n";
                                        }
                                    else
                                        {
                                            try
                                                {
                                                    fs::path p(gnuplot_executable);
                                                    fs::path dir = p.parent_path();
                                                    const std::string& gnuplot_path = dir.native();
                                                    Gnuplot::set_GNUPlotPath(gnuplot_path);
#if USE_GLOG_AND_GFLAGS
                                                    auto decimate = static_cast<unsigned int>(FLAGS_plot_decimate);

                                                    if (FLAGS_plot_detail_level >= 2 and FLAGS_show_plots)
                                                        {
                                                            Gnuplot g1("linespoints");
                                                            g1.showonscreen();  // window output
                                                            if (!FLAGS_enable_external_signal_file)
                                                                {
                                                                    g1.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, " + "PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], GPS L1 C/A (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g1.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips], PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
#else
                                                    auto decimate = static_cast<unsigned int>(absl::GetFlag(FLAGS_plot_decimate));

                                                    if (absl::GetFlag(FLAGS_plot_detail_level) >= 2 and absl::GetFlag(FLAGS_show_plots))
                                                        {
                                                            Gnuplot g1("linespoints");
                                                            g1.showonscreen();  // window output
                                                            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
                                                                {
                                                                    g1.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, " + "PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], GPS L1 C/A (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g1.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips], PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
#endif

                                                            g1.set_grid();
                                                            g1.set_xlabel("Time [s]");
                                                            g1.set_ylabel("Correlators' output");
                                                            // g1.cmd("set key box opaque");
                                                            g1.plot_xy(trk_timestamp_s, prompt, "Prompt", decimate);
                                                            g1.plot_xy(trk_timestamp_s, early, "Early", decimate);
                                                            g1.plot_xy(trk_timestamp_s, late, "Late", decimate);
                                                            if (implementation == "Galileo_E1_DLL_PLL_VEML_Tracking")
                                                                {
                                                                    g1.plot_xy(trk_timestamp_s, v_early, "Very Early", decimate);
                                                                    g1.plot_xy(trk_timestamp_s, v_late, "Very Late", decimate);
                                                                }
                                                            g1.set_legend();
                                                            g1.savetops("Correlators_outputs");

                                                            Gnuplot g2("points");
                                                            g2.showonscreen();  // window output
#if USE_GLOG_AND_GFLAGS
                                                            if (!FLAGS_enable_external_signal_file)
                                                                {
                                                                    g2.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz Constellation " + "PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g2.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips], PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
#else
                                                            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
                                                                {
                                                                    g2.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz Constellation " + "PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g2.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips], PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
#endif
                                                            g2.set_grid();
                                                            g2.set_xlabel("Inphase");
                                                            g2.set_ylabel("Quadrature");
                                                            // g2.cmd("set size ratio -1");
                                                            g2.plot_xy(promptI, promptQ);
                                                            g2.savetops("Constellation");

                                                            Gnuplot g3("linespoints");
#if USE_GLOG_AND_GFLAGS
                                                            if (!FLAGS_enable_external_signal_file)
                                                                {
                                                                    g3.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, GPS L1 C/A tracking CN0 output (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g3.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips] PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
#else
                                                            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
                                                                {
                                                                    g3.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, GPS L1 C/A tracking CN0 output (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g3.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips] PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
#endif
                                                            g3.set_grid();
                                                            g3.set_xlabel("Time [s]");
                                                            g3.set_ylabel("Reported CN0 [dB-Hz]");
                                                            g3.cmd("set key box opaque");

                                                            g3.plot_xy(trk_timestamp_s, CN0_dBHz,
                                                                std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))) + "[dB-Hz]", decimate);

                                                            g3.set_legend();
                                                            g3.savetops("CN0_output");

                                                            g3.showonscreen();  // window output

                                                            Gnuplot g4("linespoints");
#if USE_GLOG_AND_GFLAGS
                                                            if (!FLAGS_enable_external_signal_file)
                                                                {
                                                                    g4.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, GPS L1 C/A tracking CN0 output (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g4.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips] PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                                                                }
#else
                                                            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
                                                                {
                                                                    g4.set_title(std::to_string(generator_CN0_values.at(current_cn0_idx)) + " dB-Hz, GPS L1 C/A tracking CN0 output (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
                                                            else
                                                                {
                                                                    g4.set_title("D_e=" + std::to_string(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx)) + " [Hz] " + "T_e= " + std::to_string(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx)) + " [Chips] PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                                                                }
#endif
                                                            g4.set_grid();
                                                            g4.set_xlabel("Time [s]");
                                                            g4.set_ylabel("Estimated Doppler [Hz]");
                                                            g4.cmd("set key box opaque");

                                                            g4.plot_xy(trk_timestamp_s, Doppler,
                                                                std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))) + "[dB-Hz]", decimate);

                                                            g4.set_legend();
                                                            g4.savetops("Doppler");

                                                            g4.showonscreen();  // window output
                                                        }
                                                }
                                            catch (const GnuplotException& ge)
                                                {
                                                    std::cout << ge.what() << '\n';
                                                }
                                        }
                                }  // end plot
                        }          // end acquisition Delay errors loop
                }                  // end acquisition Doppler errors loop
            pull_in_results_v_v.push_back(pull_in_results_v);
        }  // end CN0 LOOP

    // build the mesh grid
    std::vector<double> doppler_error_mesh;
    std::vector<double> code_delay_error_mesh;
    for (unsigned int current_acq_doppler_error_idx = 0; current_acq_doppler_error_idx < acq_doppler_error_hz_values.size(); current_acq_doppler_error_idx++)
        {
            for (unsigned int current_acq_code_error_idx = 0; current_acq_code_error_idx < acq_delay_error_chips_values.at(current_acq_doppler_error_idx).size(); current_acq_code_error_idx++)
                {
                    doppler_error_mesh.push_back(acq_doppler_error_hz_values.at(current_acq_doppler_error_idx));
                    code_delay_error_mesh.push_back(acq_delay_error_chips_values.at(current_acq_doppler_error_idx).at(current_acq_code_error_idx));
                }
        }

    for (unsigned int current_cn0_idx = 0; current_cn0_idx < generator_CN0_values.size(); current_cn0_idx++)
        {
            std::vector<double> pull_in_result_mesh;
            pull_in_result_mesh = pull_in_results_v_v.at(current_cn0_idx);
            // plot grid
            Gnuplot g4("points palette pointsize 2 pointtype 7");
#if USE_GLOG_AND_GFLAGS
            if (FLAGS_show_plots)
#else
            if (absl::GetFlag(FLAGS_show_plots))
#endif
                {
                    g4.showonscreen();  // window output
                }
            else
                {
                    g4.disablescreen();
                }
            g4.cmd(R"(set palette defined ( 0 "black", 1 "green" ))");
            g4.cmd("set key off");
            g4.cmd("set view map");
            std::string title;
#if USE_GLOG_AND_GFLAGS
            if (!FLAGS_enable_external_signal_file)
                {
                    title = std::string("Tracking Pull-in result grid at CN0:" + std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))) + " [dB-Hz], PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz].");
                }
            else
                {
                    title = std::string("Tracking Pull-in result grid, PLL/DLL BW: " + std::to_string(FLAGS_PLL_bw_hz_start) + "," + std::to_string(FLAGS_DLL_bw_hz_start) + " [Hz], GPS L1 C/A (PRN #" + std::to_string(FLAGS_test_satellite_PRN) + ")");
                }
#else
            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
                {
                    title = std::string("Tracking Pull-in result grid at CN0:" + std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))) + " [dB-Hz], PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz].");
                }
            else
                {
                    title = std::string("Tracking Pull-in result grid, PLL/DLL BW: " + std::to_string(absl::GetFlag(FLAGS_PLL_bw_hz_start)) + "," + std::to_string(absl::GetFlag(FLAGS_DLL_bw_hz_start)) + " [Hz], GPS L1 C/A (PRN #" + std::to_string(absl::GetFlag(FLAGS_test_satellite_PRN)) + ")");
                }
#endif
            g4.set_title(title);
            g4.set_grid();
            g4.set_xlabel("Acquisition Doppler error [Hz]");
            g4.set_ylabel("Acquisition Code Delay error [Chips]");
            g4.cmd("set cbrange[0:1]");
            g4.plot_xyz(doppler_error_mesh,
                code_delay_error_mesh,
                pull_in_result_mesh);
            g4.set_legend();
#if USE_GLOG_AND_GFLAGS
            if (!FLAGS_enable_external_signal_file)
#else
            if (!absl::GetFlag(FLAGS_enable_external_signal_file))
#endif
                {
                    g4.savetops("trk_pull_in_grid_" + std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))));
                    g4.savetopdf("trk_pull_in_grid_" + std::to_string(static_cast<int>(round(generator_CN0_values.at(current_cn0_idx)))), 12);
                }
            else
                {
                    g4.savetops("trk_pull_in_grid_external_file");
                    g4.savetopdf("trk_pull_in_grid_external_file", 12);
                }
        }
}