gps_ephemeris.h

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/*!
 * \file gps_ephemeris.h
 * \brief  Interface of a GPS EPHEMERIS storage
 * \author Javier Arribas, 2013. jarribas(at)cttc.es
 *
 * -----------------------------------------------------------------------------
 *
 * Copyright (C) 2010-2020  (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.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * -----------------------------------------------------------------------------
 */


#ifndef GNSS_SDR_GPS_EPHEMERIS_H
#define GNSS_SDR_GPS_EPHEMERIS_H


#include <boost/serialization/nvp.hpp>
#include <cstdint>
#include <map>
#include <string>


/*!
 * \brief This class is a storage and orbital model functions for the GPS SV ephemeris data as described in IS-GPS-200K
 *
 * See https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf Appendix II
 */
class Gps_Ephemeris
{
public:
    /*!
     * Default constructor
     */
    Gps_Ephemeris();

    /*!
     * \brief Compute the ECEF SV coordinates and ECEF velocity
     * Implementation of Table 20-IV (IS-GPS-200K)
     * and compute the clock bias term including relativistic effect (return value)
     */
    double satellitePosition(double transmitTime);

    /*!
     * \brief Sets (\a d_satClkDrift)and returns the clock drift in seconds according to the User Algorithm for SV Clock Correction
     *  (IS-GPS-200K,  20.3.3.3.3.1)
     */
    double sv_clock_drift(double transmitTime);

    /*!
     * \brief Sets (\a d_dtr) and returns the clock relativistic correction term in seconds according to the User Algorithm for SV Clock Correction
     *  (IS-GPS-200K,  20.3.3.3.3.1)
     */
    double sv_clock_relativistic_term(double transmitTime);

    uint32_t i_satellite_PRN{};  // SV PRN NUMBER
    int32_t d_TOW{};             //!< Time of GPS Week of the ephemeris set (taken from subframes TOW) [s]
    double d_Crs{};              //!< Amplitude of the Sine Harmonic Correction Term to the Orbit Radius [m]
    double d_Delta_n{};          //!< Mean Motion Difference From Computed Value [semi-circles/s]
    double d_M_0{};              //!< Mean Anomaly at Reference Time [semi-circles]
    double d_Cuc{};              //!< Amplitude of the Cosine Harmonic Correction Term to the Argument of Latitude [rad]
    double d_e_eccentricity{};   //!< Eccentricity [dimensionless]
    double d_Cus{};              //!< Amplitude of the Sine Harmonic Correction Term to the Argument of Latitude [rad]
    double d_sqrt_A{};           //!< Square Root of the Semi-Major Axis [sqrt(m)]
    int32_t d_Toe{};             //!< Ephemeris data reference time of week (Ref. 20.3.3.4.3 IS-GPS-200K) [s]
    int32_t d_Toc{};             //!< clock data reference time (Ref. 20.3.3.3.3.1 IS-GPS-200K) [s]
    double d_Cic{};              //!< Amplitude of the Cosine Harmonic Correction Term to the Angle of Inclination [rad]
    double d_OMEGA0{};           //!< Longitude of Ascending Node of Orbit Plane at Weekly Epoch [semi-circles]
    double d_Cis{};              //!< Amplitude of the Sine Harmonic Correction Term to the Angle of Inclination [rad]
    double d_i_0{};              //!< Inclination Angle at Reference Time [semi-circles]
    double d_Crc{};              //!< Amplitude of the Cosine Harmonic Correction Term to the Orbit Radius [m]
    double d_OMEGA{};            //!< Argument of Perigee [semi-cicles]
    double d_OMEGA_DOT{};        //!< Rate of Right Ascension [semi-circles/s]
    double d_IDOT{};             //!< Rate of Inclination Angle [semi-circles/s]
    int32_t i_code_on_L2{};      //!< If 1, P code ON in L2;  if 2, C/A code ON in L2;
    int32_t i_GPS_week{};        //!< GPS week number, aka WN [week]
    bool b_L2_P_data_flag{};     //!< When true, indicates that the NAV data stream was commanded OFF on the P-code of the L2 channel
    int32_t i_SV_accuracy{};     //!< User Range Accuracy (URA) index of the SV (reference paragraph 6.2.1) for the standard positioning service user (Ref 20.3.3.3.1.3 IS-GPS-200K)
    int32_t i_SV_health{};
    double d_TGD{};        //!< Estimated Group Delay Differential: L1-L2 correction term only for the benefit of "L1 P(Y)" or "L2 P(Y)" s users [s]
    int32_t d_IODC{};      //!< Issue of Data, Clock
    int32_t d_IODE_SF2{};  //!< Issue of Data, Ephemeris (IODE), subframe 2
    int32_t d_IODE_SF3{};  //!< Issue of Data, Ephemeris(IODE), subframe 3
    int32_t i_AODO{};      //!< Age of Data Offset (AODO) term for the navigation message correction table (NMCT) contained in subframe 4 (reference paragraph 20.3.3.5.1.9) [s]

    bool b_fit_interval_flag{};  //!< indicates the curve-fit interval used by the CS (Block II/IIA/IIR/IIR-M/IIF) and SS (Block IIIA) in determining the ephemeris parameters, as follows: 0 = 4 hours, 1 = greater than 4 hours.
    double d_spare1{};
    double d_spare2{};

    double d_A_f0{};  //!< Coefficient 0 of code phase offset model [s]
    double d_A_f1{};  //!< Coefficient 1 of code phase offset model [s/s]
    double d_A_f2{};  //!< Coefficient 2 of code phase offset model [s/s^2]

    // Flags

    /*! \brief If true, enhanced level of integrity assurance.
     *
     *  If false, indicates that the conveying signal is provided with the legacy level of integrity assurance.
     *  That is, the probability that the instantaneous URE of the conveying signal exceeds 4.42 times the upper bound
     *  value of the current broadcast URA index, for more than 5.2 seconds, without an accompanying alert, is less
     *  than 1E-5 per hour. If true, indicates that the conveying signal is provided with an enhanced level of
     *  integrity assurance. That is, the probability that the instantaneous URE of the conveying signal exceeds 5.73
     *  times the upper bound value of the current broadcast URA index, for more than 5.2 seconds, without an
     *  accompanying alert, is less than 1E-8 per hour.
     */
    bool b_integrity_status_flag{};
    bool b_alert_flag{};         //!< If true, indicates  that the SV URA may be worse than indicated in d_SV_accuracy, use that SV at our own risk.
    bool b_antispoofing_flag{};  //!< If true, the AntiSpoofing mode is ON in that SV

    // clock terms derived from ephemeris data
    double d_satClkDrift{};  //!< GPS clock error
    double d_dtr{};          //!< relativistic clock correction term

    // satellite positions
    double d_satpos_X{};  //!< Earth-fixed coordinate x of the satellite [m]. Intersection of the IERS Reference Meridian (IRM) and the plane passing through the origin and normal to the Z-axis.
    double d_satpos_Y{};  //!< Earth-fixed coordinate y of the satellite [m]. Completes a right-handed, Earth-Centered, Earth-Fixed orthogonal coordinate system.
    double d_satpos_Z{};  //!< Earth-fixed coordinate z of the satellite [m]. The direction of the IERS (International Earth Rotation and Reference Systems Service) Reference Pole (IRP).

    // Satellite velocity
    double d_satvel_X{};  //!< Earth-fixed velocity coordinate x of the satellite [m]
    double d_satvel_Y{};  //!< Earth-fixed velocity coordinate y of the satellite [m]
    double d_satvel_Z{};  //!< Earth-fixed velocity coordinate z of the satellite [m]

    std::map<int, std::string> satelliteBlock;  //!< Map that stores to which block the PRN belongs https://www.navcen.uscg.gov/?Do=constellationStatus

    template <class Archive>

    /*!
     * \brief Serialize is a boost standard method to be called by the boost XML serialization. Here is used to save the ephemeris data on disk file.
     */
    inline void serialize(Archive& archive, const uint32_t version)
    {
        using boost::serialization::make_nvp;
        if (version)
            {
            };

        archive& make_nvp("i_satellite_PRN", i_satellite_PRN);  // SV PRN NUMBER
        archive& make_nvp("d_TOW", d_TOW);                      //!< Time of GPS Week of the ephemeris set (taken from subframes TOW) [s]
        archive& make_nvp("d_IODE_SF2", d_IODE_SF2);
        archive& make_nvp("d_IODE_SF3", d_IODE_SF3);
        archive& make_nvp("d_Crs", d_Crs);                        //!< Amplitude of the Sine Harmonic Correction Term to the Orbit Radius [m]
        archive& make_nvp("d_Delta_n", d_Delta_n);                //!< Mean Motion Difference From Computed Value [semi-circles/s]
        archive& make_nvp("d_M_0", d_M_0);                        //!< Mean Anomaly at Reference Time [semi-circles]
        archive& make_nvp("d_Cuc", d_Cuc);                        //!< Amplitude of the Cosine Harmonic Correction Term to the Argument of Latitude [rad]
        archive& make_nvp("d_e_eccentricity", d_e_eccentricity);  //!< Eccentricity [dimensionless]
        archive& make_nvp("d_Cus", d_Cus);                        //!< Amplitude of the Sine Harmonic Correction Term to the Argument of Latitude [rad]
        archive& make_nvp("d_sqrt_A", d_sqrt_A);                  //!< Square Root of the Semi-Major Axis [sqrt(m)]
        archive& make_nvp("d_Toe", d_Toe);                        //!< Ephemeris data reference time of week (Ref. 20.3.3.4.3 IS-GPS-200K) [s]
        archive& make_nvp("d_Toc", d_Toc);                        //!< clock data reference time (Ref. 20.3.3.3.3.1 IS-GPS-200K) [s]
        archive& make_nvp("d_Cic", d_Cic);                        //!< Amplitude of the Cosine Harmonic Correction Term to the Angle of Inclination [rad]
        archive& make_nvp("d_OMEGA0", d_OMEGA0);                  //!< Longitude of Ascending Node of Orbit Plane at Weekly Epoch [semi-circles]
        archive& make_nvp("d_Cis", d_Cis);                        //!< Amplitude of the Sine Harmonic Correction Term to the Angle of Inclination [rad]
        archive& make_nvp("d_i_0", d_i_0);                        //!< Inclination Angle at Reference Time [semi-circles]
        archive& make_nvp("d_Crc", d_Crc);                        //!< Amplitude of the Cosine Harmonic Correction Term to the Orbit Radius [m]
        archive& make_nvp("d_OMEGA", d_OMEGA);                    //!< Argument of Perigee [semi-cicles]
        archive& make_nvp("d_OMEGA_DOT", d_OMEGA_DOT);            //!< Rate of Right Ascension [semi-circles/s]
        archive& make_nvp("d_IDOT", d_IDOT);                      //!< Rate of Inclination Angle [semi-circles/s]
        archive& make_nvp("i_code_on_L2", i_code_on_L2);          //!< If 1, P code ON in L2;  if 2, C/A code ON in L2;
        archive& make_nvp("i_GPS_week", i_GPS_week);              //!< GPS week number, aka WN [week]
        archive& make_nvp("b_L2_P_data_flag", b_L2_P_data_flag);  //!< When true, indicates that the NAV data stream was commanded OFF on the P-code of the L2 channel
        archive& make_nvp("i_SV_accuracy", i_SV_accuracy);        //!< User Range Accuracy (URA) index of the SV (reference paragraph 6.2.1) for the standard positioning service user (Ref 20.3.3.3.1.3 IS-GPS-200K)
        archive& make_nvp("i_SV_health", i_SV_health);
        archive& make_nvp("d_TGD", d_TGD);    //!< Estimated Group Delay Differential: L1-L2 correction term only for the benefit of "L1 P(Y)" or "L2 P(Y)" s users [s]
        archive& make_nvp("d_IODC", d_IODC);  //!< Issue of Data, Clock
        archive& make_nvp("i_AODO", i_AODO);  //!< Age of Data Offset (AODO) term for the navigation message correction table (NMCT) contained in subframe 4 (reference paragraph 20.3.3.5.1.9) [s]

        archive& make_nvp("b_fit_interval_flag", b_fit_interval_flag);  //!< Indicates the curve-fit interval used by the CS (Block II/IIA/IIR/IIR-M/IIF) and SS (Block IIIA) in determining the ephemeris parameters, as follows: 0 = 4 hours, 1 = greater than 4 hours.
        archive& make_nvp("d_spare1", d_spare1);
        archive& make_nvp("d_spare2", d_spare2);

        archive& make_nvp("d_A_f0", d_A_f0);  //!< Coefficient 0 of code phase offset model [s]
        archive& make_nvp("d_A_f1", d_A_f1);  //!< Coefficient 1 of code phase offset model [s/s]
        archive& make_nvp("d_A_f2", d_A_f2);  //!< Coefficient 2 of code phase offset model [s/s^2]

        archive& make_nvp("b_integrity_status_flag", b_integrity_status_flag);
        archive& make_nvp("b_alert_flag", b_alert_flag);                //!< If true, indicates that the SV URA may be worse than indicated in d_SV_accuracy, use that SV at our own risk.
        archive& make_nvp("b_antispoofing_flag", b_antispoofing_flag);  //!< If true, the AntiSpoofing mode is ON in that SV
    }

private:
    /*
     * Accounts for the beginning or end of week crossover
     *
     * See paragraph 20.3.3.3.3.1 (IS-GPS-200K)
     * \param[in]  -  time in seconds
     * \param[out] -  corrected time, in seconds
     */
    double check_t(double time);
};

#endif