/// <summary>
/// Returns the position of Sun ECEF coordinates (meters) at the indicated time.
/// </summary>
/// <param name="t">the time to look up</param>
/// <returns>the position of the Sun at time (as a Triple)</returns>
/// @throw InvalidRequest If the request can not be completed for any
/// reason, this is thrown. The text may have additional
/// information as to why the request failed.
/// @warning This method yields an approximate result, given that pole movement
/// is not taken into account, neither precession nor nutation.
public void GetPosition(Time time, ErpItem erpv)
{
//gpst2utc
Time tutc = time.GpstToUtc();
// Test if the time interval is correct
if ((tutc < initialTime) || (tutc > finalTime))
{
throw new Exception("Provided epoch is out of bounds!");
}
//utc -> ut1
Time tut = tutc + erpv.Ut12Utc;
//sun and moon position in eci
XYZ rs = new XYZ(0, 0, 0);
XYZ rm = new XYZ(0, 0, 0);
sunmoonpos_eci(tut, ref rs, ref rm);
//eci to ecef transformation matrix
double[] U = new double[9];//3*3 transformation matrix
double gmst_ = 0.0;
eci2ecef(tutc, erpv, ref U, ref gmst_);
//sun and moon postion in ecef
char[] tr = new char[2]; tr[0] = 'N'; tr[1] = 'N';
double[] rsn = new double[3]; rsn[0] = rs.X; rsn[1] = rs.Y; rsn[2] = rs.Z;
double[] rmn = new double[3]; rmn[0] = rm.X; rmn[1] = rm.Y; rmn[2] = rm.Z;
double[] rsun = new double[3]; double[] rmoon = new double[3];
matmul(tr, 3, 1, 3, 1.0, U, rsn, 0.0, ref rsun);
matmul(tr, 3, 1, 3, 1.0, U, rmn, 0.0, ref rmoon);
this.rSun = new XYZ(rsun);
this.rMoon = new XYZ(rmoon);
this.gmst = gmst_;
}
/// <summary>
/// 根据太阳计算卫星偏差
/// </summary>
/// <param name="prn"></param>
/// <param name="eph"></param>
/// <param name="emissionTime"></param>
/// <returns></returns>
private XYZ GetSatAntOff(SatelliteNumber prn, IEphemeris eph, Time emissionTime)
{
ErpItem erpv = null;
if (DataSouceProvider.ErpDataService != null)
{
erpv = DataSouceProvider.ErpDataService.Get(emissionTime);
}
if (erpv == null)
{
erpv = ErpItem.Zero;
}
XYZ rsun = new XYZ();
//sun position in ecef
// rsun = EpochSat.EpochInfo.DataSouceProvider.UniverseObjectProvider.GetSunPosition(emissionTime);
this.DataSouceProvider.UniverseObjectProvider.GetSunPosition(emissionTime, erpv, ref rsun);
//unit vetcors of satellite fixed coordinates
XYZ ez = -1 * eph.XYZ.UnitVector();
XYZ es = (rsun - eph.XYZ).UnitVector();
//outer product of 3D vectors
XYZ r = new XYZ();
r.X = ez.Y * es.Z - ez.Z * es.Y;
r.Y = ez.Z * es.X - ez.X * es.Z;
r.Z = ez.X * es.Y - ez.Y * es.X;
XYZ r0 = new XYZ();
r0.X = r.Y * ez.Z - r.Z * ez.Y;
r0.Y = r.Z * ez.X - r.X * ez.Z;
r0.Z = r.X * ez.Y - r.Y * ez.X;
XYZ ex = r0.UnitVector();
XYZ ey = r.UnitVector();
//XYZ ex = new XYZ();
//ex.X = ey.Y * ez.Z - ey.Z * ez.Y;
//ex.Y = ey.Z * ez.X - ey.X * ez.Z;
//ex.Z = ey.X * ez.Y - ey.Y * ez.X;
//use L1 value
if (DataSouceProvider.AntennaDataSource == null)
{
return(new XYZ());
}
IAntenna antenna = DataSouceProvider.AntennaDataSource.Get(prn.ToString(), emissionTime);
//如果为空，则返回 0 坐标
if (antenna == null)
{
return(new XYZ());
}
// Get antenna eccentricity for frequency "G01" (L1), in
// satellite reference system.
// NOTE: It is NOT in ECEF, it is in UEN!!!
RinexSatFrequency freq = new RinexSatFrequency(prn, 1);
// NEU satAnt = antenna.GetAntennaEccentricity(AntennaFrequency.G01);
NEU satAnt = antenna.GetPcoValue(freq);
XYZ dant = new XYZ();
dant.X = satAnt.E * ex.X + satAnt.N * ey.X + satAnt.U * ez.X;
dant.Y = satAnt.E * ex.Y + satAnt.N * ey.Y + satAnt.U * ez.Y;
dant.Z = satAnt.E * ex.Z + satAnt.N * ey.Z + satAnt.U * ez.Z;
// Unitary vector from satellite to Earth mass center (ECEF)
XYZ satToEarthUnit = (-1.0) * eph.XYZ.UnitVector();
// Unitary vector from Earth mass center to Sun (ECEF)
XYZ earthToSunUnit = rsun.UnitVector();
// rj = rk x ri: Rotation axis of solar panels (ECEF)
XYZ rj = satToEarthUnit.Cross(earthToSunUnit);
// Redefine ri: ri = rj x rk (ECEF)
earthToSunUnit = rj.Cross(satToEarthUnit);
// Let's funcKeyToDouble ri to an unitary vector. (ECEF)
earthToSunUnit = earthToSunUnit.UnitVector();
XYZ dant1 = new XYZ();
dant1.X = satAnt.E * rj.X + satAnt.N * earthToSunUnit.X + satAnt.U * satToEarthUnit.X;
dant1.Y = satAnt.E * rj.Y + satAnt.N * earthToSunUnit.Y + satAnt.U * satToEarthUnit.Y;
dant1.Z = satAnt.E * rj.Z + satAnt.N * earthToSunUnit.Z + satAnt.U * satToEarthUnit.Z;
return(dant1);
}
/// <summary>
/// eci to ecef transformation matrix
/// compute eci to ecef transformation matrix
/// </summary>
/// <param name="tutc">time in UTC</param>
/// <param name="erpv">erp value (xp, yp, ut1_utc, lod) (rad, rad, s, s/d)</param>
/// <param name="U">eci to ecef transformation matrix (3*3)</param>
/// <param name="gmst">greenwich mean sidereal time (rad)</param>
private void eci2ecef(Time tutc, ErpItem erpv, ref double[] U, ref double gmst)
{
Time tutc_ = tutc;
Time gpstime0 = new Time(2000, 1, 1, 12);
//terrestrial time
Time tgps = tutc_.UtcToGpsT();
double t = ((double)(tgps - gpstime0) + 19.0 + 32.184) / 86400.0 / 36525.0;
double t2 = t * t; double t3 = t2 * t;
double[] f = new double[5];
//astronomical arguments
ast_args(t, ref f);
/* iau 1976 precession */
double ze = (2306.2181 * t + 0.30188 * t2 + 0.017998 * t3) * SunMoonPosition.DAS2R;
double th = (2004.3109 * t - 0.42665 * t2 - 0.041833 * t3) * SunMoonPosition.DAS2R;
double z = (2306.2181 * t + 1.09468 * t2 + 0.018203 * t3) * SunMoonPosition.DAS2R;
double eps = (84381.448 - 46.8150 * t - 0.00059 * t2 + 0.001813 * t3) * SunMoonPosition.DAS2R;
double[] R1 = Rz(-z); double[] R2 = Ry(th); double[] R3 = Rz(-ze);
char[] tr = new char[2]; tr[0] = 'N'; tr[1] = 'N';
double[] R = new double[9];
matmul(tr, 3, 3, 3, 1.0, R1, R2, 0.0, ref R);
double[] P = new double[9];
matmul(tr, 3, 3, 3, 1.0, R, R3, 0.0, ref P);/* P=Rz(-z)*Ry(th)*Rz(-ze) */
// iau 1980 nutation
double dpsi = 0.0, deps = 0.0;
nut_iau1980(t, f, ref dpsi, ref deps);
R1 = Rx(-eps - deps); R2 = Rz(-dpsi); R3 = Rx(eps);
R = new double[9];
matmul(tr, 3, 3, 3, 1.0, R1, R2, 0.0, ref R);
double[] N = new double[9];
matmul(tr, 3, 3, 3, 1.0, R, R3, 0.0, ref N); /* N=Rx(-eps)*Rz(-dspi)*Rx(eps) */
//greenwich aparent sidereal time (rad)
double gmst_ = Time.UtcToGmst(tutc_, erpv.Ut12Utc);
double gast = gmst_ + dpsi * Math.Cos(eps);
gast += (0.00264 * Math.Sin(f[4]) + 0.000063 * Math.Sin(2.0 * f[4])) * SunMoonPosition.DAS2R;
/* eci to ecef transformation matrix */
R1 = Ry(-erpv.Xpole * SunMoonPosition.DAS2R); R2 = Rx(-erpv.Ypole * SunMoonPosition.DAS2R); R3 = Rz(gast);
double[] W = new double[9];
matmul(tr, 3, 3, 3, 1.0, R1, R2, 0.0, ref W);
R = new double[9];
matmul(tr, 3, 3, 3, 1.0, W, R3, 0.0, ref R); /* W=Ry(-xp)*Rx(-yp) */
double[] NP = new double[9];
matmul(tr, 3, 3, 3, 1.0, N, P, 0.0, ref NP);
double[] U_ = new double[9];
matmul(tr, 3, 3, 3, 1.0, R, NP, 0.0, ref U_); /* U=W*Rz(gast)*N*P */
for (int i = 0; i < 9; i++)
{
U[i] = U_[i];
}
gmst = gmst_;
}
