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https://github.com/gnss-sdr/gnss-sdr
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Add Doppler prediction in almanacs
This commit is contained in:
Carles Fernandez
parent
08782a2085
commit
9a91fb3192
@ -19,6 +19,7 @@
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#include "gnss_sdr_supl_client.h"
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#include "GPS_L1_CA.h"
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#include "MATH_CONSTANTS.h"
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#include <boost/archive/xml_iarchive.hpp>
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#include <boost/archive/xml_oarchive.hpp>
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#include <boost/serialization/map.hpp>
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@ -858,6 +859,7 @@ bool Gnss_Sdr_Supl_Client::read_gal_almanac_from_gsa(const std::string& file_nam
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Galileo_Almanac gal_alm;
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try
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{
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const double sqrtAnominal = 5440.588203494; // square root of Galileo nominal orbit semi-major axis
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uint32_t prn = static_cast<uint32_t>(std::stoi(almanac.child_value("SVID")));
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gal_alm.PRN = prn;
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gal_alm.toa = std::stoi(almanac.child("almanac").child_value("t0a"));
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@ -866,7 +868,7 @@ bool Gnss_Sdr_Supl_Client::read_gal_almanac_from_gsa(const std::string& file_nam
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gal_alm.delta_i = std::stod(almanac.child("almanac").child_value("deltai"));
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gal_alm.M_0 = std::stod(almanac.child("almanac").child_value("m0"));
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gal_alm.ecc = std::stod(almanac.child("almanac").child_value("ecc"));
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gal_alm.sqrtA = std::stod(almanac.child("almanac").child_value("aSqRoot"));
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gal_alm.sqrtA = std::stod(almanac.child("almanac").child_value("aSqRoot")) + sqrtAnominal;
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gal_alm.OMEGA_0 = std::stod(almanac.child("almanac").child_value("omega0"));
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gal_alm.omega = std::stod(almanac.child("almanac").child_value("w"));
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gal_alm.OMEGAdot = std::stod(almanac.child("almanac").child_value("omegaDot"));
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@ -6,6 +6,7 @@
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set(SYSTEM_PARAMETERS_SOURCES
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gnss_almanac.cc
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gnss_ephemeris.cc
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gnss_satellite.cc
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gnss_signal.cc
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@ -36,7 +36,10 @@ public:
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/*!
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* Default constructor
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*/
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Beidou_Dnav_Almanac() = default;
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Beidou_Dnav_Almanac()
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{
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this->System = 'B';
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};
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int SV_health{}; //!< SV Health
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@ -36,7 +36,10 @@ public:
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/*!
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* Default constructor
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*/
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Galileo_Almanac() = default;
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Galileo_Almanac()
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{
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this->System = 'E';
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};
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int32_t IODa{};
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int32_t E5b_HS{};
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275
src/core/system_parameters/gnss_almanac.cc
Normal file
275
src/core/system_parameters/gnss_almanac.cc
Normal file
@ -0,0 +1,275 @@
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/*!
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* \file gnss_almanac.cc
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* \brief Base class for GNSS almanac storage
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* \author Carles Fernandez, 2022. cfernandez(at)cttc.es
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*
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* -----------------------------------------------------------------------------
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*
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* GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
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* This file is part of GNSS-SDR.
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*
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* Copyright (C) 2010-2022 (see AUTHORS file for a list of contributors)
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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* -----------------------------------------------------------------------------
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*/
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#include "gnss_almanac.h"
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#include "MATH_CONSTANTS.h"
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#include "gnss_frequencies.h"
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#include <algorithm>
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#include <cmath>
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#include <functional>
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#include <numeric>
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#include <vector>
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double Gnss_Almanac::check_t(double time) const
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{
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const double half_week = 302400.0; // seconds
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double corrTime = time;
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if (time > half_week)
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{
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corrTime = time - 2.0 * half_week;
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}
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else if (time < -half_week)
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{
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corrTime = time + 2.0 * half_week;
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}
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return corrTime;
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}
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double Gnss_Almanac::predicted_doppler(double rx_time_s,
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double lat,
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double lon,
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double h,
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double ve,
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double vn,
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double vu,
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int band) const
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{
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const double RE_WGS84 = 6378137.0; //!< earth semimajor axis (WGS84) (m)
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const double FE_WGS84 = (1.0 / 298.257223563); //!< earth flattening (WGS84)
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const double lat_rad = lat * D2R;
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const double lon_rad = lon * D2R;
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const double sinp = sin(lat_rad);
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const double cosp = cos(lat_rad);
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const double sinl = sin(lon_rad);
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const double cosl = cos(lon_rad);
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const double e2 = FE_WGS84 * (2.0 - FE_WGS84);
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const double v = RE_WGS84 / std::sqrt(1.0 - e2 * sinp * sinp);
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// Position in EFEF
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const std::vector<double> pos_rx = {(v + h) * cosp * cosl, (v + h) * cosp * sinl, (v * (1.0 - e2) + h) * sinp};
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// Velovity in EFEF
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const double t = cosp * vu - sinp * vn;
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const std::vector<double> vel_rx = {cosl * t - sinl * ve, sinl * t + cosl * ve, sinp * vu + cosp * vn};
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std::array<double, 7> sat_pos_vel = {0};
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satellitePosVelComputation(rx_time_s, sat_pos_vel);
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const std::vector<double> pos_sat = {sat_pos_vel[0], sat_pos_vel[1], sat_pos_vel[2]};
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const std::vector<double> vel_sat = {sat_pos_vel[3], sat_pos_vel[4], sat_pos_vel[5]};
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std::vector<double> x_sr = pos_sat;
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std::transform(x_sr.begin(), x_sr.end(), pos_rx.begin(), x_sr.begin(), std::minus<double>()); // pos_sat - pos_rx
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const double norm_x_sr = std::sqrt(std::inner_product(x_sr.begin(), x_sr.end(), x_sr.begin(), 0.0)); // Euclidean norm
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std::vector<double> v_sr = vel_sat;
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std::transform(v_sr.begin(), v_sr.end(), vel_rx.begin(), v_sr.begin(), std::minus<double>()); // vel_sat - vel_rx
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const double radial_vel = std::inner_product(v_sr.begin(), v_sr.end(), x_sr.begin(), 0.0) / norm_x_sr;
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const double predicted_doppler_normalized = -(radial_vel / SPEED_OF_LIGHT_M_S);
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double predicted_doppler = 0.0;
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if (this->System == 'E') // Galileo
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{
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if (band == 1)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ1;
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}
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else if (band == 5)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ5;
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}
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else if (band == 6)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ6;
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}
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else if (band == 7)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ7;
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}
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else if (band == 8)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ8;
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}
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else
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{
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predicted_doppler = 0.0;
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}
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}
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else if (this->System == 'G') // GPS
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{
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if (band == 1)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ1;
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}
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else if (band == 2)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ2;
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}
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else if (band == 5)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ5;
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}
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else
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{
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predicted_doppler = 0.0;
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}
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}
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else if (this->System == 'B') // Beidou
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{
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if (band == 1)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ1_BDS;
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}
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else if (band == 2)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ2_BDS;
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}
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else if (band == 3)
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{
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predicted_doppler = predicted_doppler_normalized * FREQ3_BDS;
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}
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else
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{
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predicted_doppler = 0.0;
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}
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}
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else
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{
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predicted_doppler = 0.0;
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}
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return predicted_doppler;
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}
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void Gnss_Almanac::satellitePosVelComputation(double transmitTime, std::array<double, 7>& pos_vel_dtr) const
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{
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// Restore semi-major axis
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const double a = this->sqrtA * this->sqrtA;
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// Computed mean motion
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double n;
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if (this->System == 'E')
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{
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n = sqrt(GALILEO_GM / (a * a * a));
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}
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else if (this->System == 'B')
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{
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n = sqrt(BEIDOU_GM / (a * a * a));
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}
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else
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{
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n = sqrt(GPS_GM / (a * a * a));
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}
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// Time from ephemeris reference epoch
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const double tk = check_t(transmitTime - static_cast<double>(this->toa));
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// Mean anomaly
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const double M = this->M_0 * GNSS_PI + n * tk;
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// Initial guess of eccentric anomaly
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double E = M;
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double E_old;
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double dE;
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// --- Iteratively compute eccentric anomaly -------------------------------
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for (int32_t ii = 1; ii < 20; ii++)
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{
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E_old = E;
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E = M + this->ecc * sin(E);
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dE = fmod(E - E_old, 2.0 * GNSS_PI);
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if (fabs(dE) < 1e-12)
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{
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// Necessary precision is reached, exit from the loop
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break;
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}
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}
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const double sek = sin(E);
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const double cek = cos(E);
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const double OneMinusecosE = 1.0 - this->ecc * cek;
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const double sq1e2 = sqrt(1.0 - this->ecc * this->ecc);
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const double ekdot = n / OneMinusecosE;
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// Compute the true anomaly
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const double tmp_Y = sq1e2 * sek;
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const double tmp_X = cek - this->ecc;
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const double nu = atan2(tmp_Y, tmp_X);
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// Compute angle phi (argument of Latitude)
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const double phi = nu + this->omega * GNSS_PI;
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const double pkdot = sq1e2 * ekdot / OneMinusecosE;
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// Correct argument of latitude
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const double suk = sin(phi);
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const double cuk = cos(phi);
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// Correct radius
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const double r = a * OneMinusecosE;
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const double rkdot = a * this->ecc * sek * ekdot;
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// Correct inclination
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double i;
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if (this->System == 'E')
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{
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i = ((56.0 / 180.0) + this->delta_i) * GNSS_PI;
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}
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else
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{
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i = (0.3 + this->delta_i) * GNSS_PI;
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}
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const double sik = sin(i);
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const double cik = cos(i);
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// Compute the angle between the ascending node and the Greenwich meridian
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double Omega;
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double Omega_dot;
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if (this->System == 'B')
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{
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Omega_dot = this->OMEGAdot * GNSS_PI - BEIDOU_OMEGA_EARTH_DOT;
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Omega = this->OMEGA_0 * GNSS_PI + Omega_dot * tk - BEIDOU_OMEGA_EARTH_DOT * static_cast<double>(this->toa);
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}
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else
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{
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Omega_dot = this->OMEGAdot * GNSS_PI - GNSS_OMEGA_EARTH_DOT;
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Omega = this->OMEGA_0 * GNSS_PI + Omega_dot * tk - GNSS_OMEGA_EARTH_DOT * static_cast<double>(this->toa);
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}
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const double sok = sin(Omega);
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const double cok = cos(Omega);
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// --- Compute satellite coordinates in Earth-fixed coordinates
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const double xprime = r * cuk;
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const double yprime = r * suk;
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pos_vel_dtr[0] = xprime * cok - yprime * cik * sok;
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pos_vel_dtr[1] = xprime * sok + yprime * cik * cok;
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pos_vel_dtr[2] = yprime * sik;
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// Satellite's velocity
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const double xpkdot = rkdot * cuk - yprime * pkdot;
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const double ypkdot = rkdot * suk + xprime * pkdot;
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const double tmp = ypkdot * cik;
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pos_vel_dtr[3] = -Omega_dot * pos_vel_dtr[1] + xpkdot * cok - tmp * sok;
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pos_vel_dtr[4] = Omega_dot * pos_vel_dtr[0] + xpkdot * sok + tmp * cok;
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pos_vel_dtr[5] = ypkdot * sik;
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pos_vel_dtr[6] = 0;
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}
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@ -18,6 +18,7 @@
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#ifndef GNSS_SDR_GNSS_ALMANAC_H
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#define GNSS_SDR_GNSS_ALMANAC_H
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#include <array>
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#include <cstdint>
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/** \addtogroup Core
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@ -37,6 +38,42 @@ public:
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*/
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Gnss_Almanac() = default;
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/* \brief Computes prediction of the Doppler shift for a given time and receiver's position and velocity.
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* \f[
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* f_{d} = - \mathbf{v} \frac{\mathbf{x}^{T}}{\left| \mathbf{x} \right| } \frac{f_{L}}{c}
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* \f]
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* where:
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* \f[
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* \mathbf{v} = \mathbf{v}_{sat} - \mathbf{v}_{rx}
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* \f]
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* \f[
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* \mathbf{x} = \mathbf{x}_{sat} - \mathbf{x}_{rx}
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* \f]
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* \f[
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* \left| \mathbf{x} \right| = \sqrt{\mathbf{x}\mathbf{x}^{T}}
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* \f]
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*
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* @param[in] rx_time_s Time of Week in seconds
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* @param[in] lat Receiver's latitude in degrees
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* @param[in] lon Receiver's longitude in degrees
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* @param[in] h Receiver's height in meters
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* @param[in] ve Receiver's velocity in the East direction [m/s]
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* @param[in] vn Receiver's velocity in the North direction [m/s]
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* @param[in] vu Receiver's velocity in the Up direction [m/s]
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* @param[in] band Signal band for which the Doppler will be computed
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* (1: L1 C/A, E1B, BI1; 2: L2C, BI2; 3: BI3; 5: L5/E5a; 6: E6B; 7: E5b; 8: E5a+E5b)
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*/
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double predicted_doppler(double rx_time_s,
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double lat,
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double lon,
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double h,
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double ve,
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double vn,
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double vu,
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int band) const;
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void satellitePosVelComputation(double transmitTime, std::array<double, 7>& pos_vel_dtr) const;
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uint32_t PRN{}; //!< SV PRN NUMBER
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double delta_i{}; //!< Inclination Angle at Reference Time (relative to i_0 = 0.30 semi-circles)
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int32_t toa{}; //!< Almanac data reference time of week [s]
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@ -49,6 +86,11 @@ public:
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double OMEGAdot{}; //!< Rate of Right Ascension [semi-circles/s]
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double af0{}; //!< Coefficient 0 of code phase offset model [s]
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double af1{}; //!< Coefficient 1 of code phase offset model [s/s]
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protected:
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char System{}; //!< Character ID of the GNSS system. 'G': GPS. 'E': Galileo. 'B': BeiDou
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private:
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double check_t(double time) const;
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};
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@ -193,10 +193,7 @@ void Gnss_Ephemeris::satellitePosVelComputation(double transmitTime, std::array<
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const double n = n0 + this->delta_n;
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// Mean anomaly
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double M = this->M_0 + n * tk;
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// Reduce mean anomaly to between 0 and 2pi
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M = fmod((M + 2.0 * GNSS_PI), (2.0 * GNSS_PI));
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const double M = this->M_0 + n * tk;
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// Initial guess of eccentric anomaly
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double E = M;
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@ -228,10 +225,9 @@ void Gnss_Ephemeris::satellitePosVelComputation(double transmitTime, std::array<
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const double nu = atan2(tmp_Y, tmp_X);
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// Compute angle phi (argument of Latitude)
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double phi = nu + this->omega;
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const double phi = nu + this->omega;
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// Reduce phi to between 0 and 2*pi rad
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phi = fmod((phi), (2.0 * GNSS_PI));
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const double s2pk = sin(2.0 * phi);
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const double c2pk = cos(2.0 * phi);
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const double pkdot = sq1e2 * ekdot / OneMinusecosE;
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@ -266,8 +262,6 @@ void Gnss_Ephemeris::satellitePosVelComputation(double transmitTime, std::array<
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Omega = this->OMEGA_0 + Omega_dot * tk - GNSS_OMEGA_EARTH_DOT * static_cast<double>(this->toe);
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}
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// Reduce to between 0 and 2*pi rad
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Omega = fmod((Omega + 2.0 * GNSS_PI), (2.0 * GNSS_PI));
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const double sok = sin(Omega);
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const double cok = cos(Omega);
|
||||
|
||||
@ -352,9 +346,6 @@ double Gnss_Ephemeris::sv_clock_relativistic_term(double transmitTime) const
|
||||
// Mean anomaly
|
||||
const double M = this->M_0 + n * tk;
|
||||
|
||||
// Reduce mean anomaly to between 0 and 2pi
|
||||
// M = fmod((M + 2.0 * GNSS_PI), (2.0 * GNSS_PI));
|
||||
|
||||
// Initial guess of eccentric anomaly
|
||||
double E = M;
|
||||
double E_old;
|
||||
|
||||
@ -39,6 +39,20 @@ public:
|
||||
|
||||
/*!
|
||||
* \brief Computes prediction of the Doppler shift for a given time and receiver's position and velocity.
|
||||
* \f[
|
||||
* f_{d} = - \mathbf{v} \frac{\mathbf{x}^{T}}{\left| \mathbf{x} \right| } \frac{f_{L}}{c}
|
||||
* \f]
|
||||
* where:
|
||||
* \f[
|
||||
* \mathbf{v} = \mathbf{v}_{sat} - \mathbf{v}_{rx}
|
||||
* \f]
|
||||
* \f[
|
||||
* \mathbf{x} = \mathbf{x}_{sat} - \mathbf{x}_{rx}
|
||||
* \f]
|
||||
* \f[
|
||||
* \left| \mathbf{x} \right| = \sqrt{\mathbf{x}\mathbf{x}^{T}}
|
||||
* \f]
|
||||
*
|
||||
* @param[in] rx_time_s Time of Week in seconds
|
||||
* @param[in] lat Receiver's latitude in degrees
|
||||
* @param[in] lon Receiver's longitude in degrees
|
||||
|
||||
@ -38,7 +38,10 @@ public:
|
||||
/*!
|
||||
* Default constructor
|
||||
*/
|
||||
Gps_Almanac() = default;
|
||||
Gps_Almanac()
|
||||
{
|
||||
this->System = 'G';
|
||||
};
|
||||
|
||||
int32_t SV_health{}; //!< SV Health
|
||||
int32_t AS_status{}; //!< Anti-Spoofing Flags and SV Configuration
|
||||
|
||||
Loading…
Reference in New Issue
Block a user