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sgp4
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Removed tle struct at t = 0.0;

feature/19
Daniel Warner 2011-03-26 19:17:12 +00:00
parent 30bcc6900d
commit 896548d782
3 changed files with 106 additions and 116 deletions
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175
SGDP4.cpp
View File

@ -27,27 +27,39 @@ void SGDP4::SetTle(const Tle& tle) {
/* /*
* generate julian date for tle epoch * generate julian date for tle epoch
*/ */
int year = static_cast<int> (tle.GetField(Tle::FLD_EPOCHYEAR)); epoch_ = tle.GetEpoch();
if (year < 57)
year += 2000;
else
year += 1900;
double day = tle.GetField(Tle::FLD_EPOCHDAY);
Julian jul(year, day);
epoch_ = jul;
/*
* recover original mean motion (xnodp) and semimajor axis (aodp)
* from input elements
*/
double a1 = pow(Globals::XKE() / MeanMotion(), Globals::TOTHRD());
cosio_ = cos(Inclination());
double theta2 = cosio_ * cosio_;
x3thm1_ = 3.0 * theta2 - 1.0;
double eosq = Eccentricity() * Eccentricity();
double betao2 = 1.0 - eosq;
double betao = sqrt(betao2);
double del1 = 1.5 * Globals::CK2() * x3thm1_ / (a1 * a1 * betao * betao2);
double ao = a1 * (1.0 - del1 * (0.5 * Globals::TOTHRD() + del1 * (1.0 + 134.0 / 81.0 * del1)));
double delo = 1.5 * Globals::CK2() * x3thm1_ / (ao * ao * betao * betao2);
recovered_semi_major_axis = 0.0; recovered_mean_motion_ = MeanMotion() / (1.0 + delo);
recovered_mean_motion_ = 0.0; recovered_semi_major_axis_ = ao / (1.0 - delo);
Initialize(); /*
* find perigee and period
*/
perigee_ = (RecoveredSemiMajorAxis() * (1.0 - Eccentricity()) - Globals::AE()) * Globals::XKMPER();
period_ = Globals::TWOPI() / RecoveredMeanMotion();
Initialize(theta2, betao2, betao);
} }
void SGDP4::Initialize() { void SGDP4::Initialize(const double& theta2, const double& betao2, const double& betao) {
cosio_ = 0.0; cosio_ = 0.0;
sinio_ = 0.0; sinio_ = 0.0;
aodp_ = 0.0;
eta_ = 0.0; eta_ = 0.0;
coef1_ = 0.0; coef1_ = 0.0;
@ -79,55 +91,22 @@ void SGDP4::Initialize() {
gsto_ = 0.0; gsto_ = 0.0;
use_simple_model_ = false; if (Period() >= 225.0) {
use_deep_space_ = true;
} else {
use_deep_space_ = false; use_deep_space_ = false;
use_simple_model_ = false;
/*
* recover original mean motion and semimajor axis (aodp)
* from input elements
*/
cosio_ = cos(tle_data_0_.xincl);
sinio_ = sin(tle_data_0_.xincl);
double theta2 = cosio_ * cosio_;
x3thm1_ = 3.0 * theta2 - 1.0;
double eosq = tle_data_0_.eo * tle_data_0_.eo;
double betao2 = 1.0 - eosq;
double betao = sqrt(betao2);
{
double a1 = pow(Globals::XKE() / tle_data_0_.xno, Globals::TOTHRD());
double del1 = 1.5 * Globals::CK2() * x3thm1_ / (a1 * a1 * betao * betao2);
double ao = a1 * (1.0 - del1 * (0.5 * Globals::TOTHRD() + del1 * (1.0 + 134.0 / 81.0 * del1)));
double delo = 1.5 * Globals::CK2() * x3thm1_ / (ao * ao * betao * betao2);
/*
* recovered mean motion
*/
tle_data_0_.xno = tle_data_0_.xno / (1.0 + delo);
/*
* recovered semimajor axis
*/
aodp_ = ao / (1.0 - delo);
}
double rp = aodp_ * (1.0 - tle_data_0_.eo);
double perigee = (rp - Globals::AE()) * Globals::XKMPER();
double period = Globals::TWOPI() / tle_data_0_.xno;
/* /*
* for perigee less than 220 kilometers, the simple_model flag is set and * for perigee less than 220 kilometers, the simple_model flag is set and
* the equations are truncated to linear variation in sqrt a and * the equations are truncated to linear variation in sqrt a and
* quadratic variation in mean anomly. also, the c3 term, the * quadratic variation in mean anomly. also, the c3 term, the
* delta omega term and the delta m term are dropped * delta omega term and the delta m term are dropped
*/ */
use_deep_space_ = false; if (Perigee() < 220.0) {
use_simple_model_ = false;
if (period >= 225.0) {
use_deep_space_ = true;
} else {
if (rp < (220.0 / Globals::XKMPER() + Globals::AE()))
use_simple_model_ = true; use_simple_model_ = true;
} }
}
double s4_ = Globals::S(); double s4_ = Globals::S();
double qoms24_ = Globals::QOMS2T(); double qoms24_ = Globals::QOMS2T();
@ -135,42 +114,42 @@ void SGDP4::Initialize() {
* for perigee below 156km, the values of * for perigee below 156km, the values of
* s4 and qoms2t are altered * s4 and qoms2t are altered
*/ */
if (perigee < 156.0) { if (Perigee() < 156.0) {
s4_ = perigee - 78.0; s4_ = Perigee() - 78.0;
if (perigee <= 98.0) { if (Perigee() <= 98.0) {
s4_ = 20.0; s4_ = 20.0;
} }
qoms24_ = pow((120.0 - s4_) * Globals::AE() / Globals::XKMPER(), 4.0); qoms24_ = pow((120.0 - s4_) * Globals::AE() / Globals::XKMPER(), 4.0);
s4_ = s4_ / Globals::XKMPER() + Globals::AE(); s4_ = s4_ / Globals::XKMPER() + Globals::AE();
} }
double pinvsq = 1.0 / (aodp_ * aodp_ * betao2 * betao2); double pinvsq = 1.0 / (RecoveredSemiMajorAxis() * RecoveredSemiMajorAxis() * betao2 * betao2);
double tsi = 1.0 / (aodp_ - s4_); double tsi = 1.0 / (RecoveredSemiMajorAxis() - s4_);
eta_ = aodp_ * tle_data_0_.eo * tsi; eta_ = RecoveredSemiMajorAxis() * Eccentricity() * tsi;
double etasq = eta_ * eta_; double etasq = eta_ * eta_;
double eeta = tle_data_0_.eo * eta_; double eeta = Eccentricity() * eta_;
double psisq = fabs(1.0 - etasq); double psisq = fabs(1.0 - etasq);
double coef = qoms24_ * pow(tsi, 4.0); double coef = qoms24_ * pow(tsi, 4.0);
coef1_ = coef / pow(psisq, 3.5); coef1_ = coef / pow(psisq, 3.5);
double c2 = coef1_ * tle_data_0_.xno * (aodp_ * (1.0 + 1.5 * etasq + eeta * double c2 = coef1_ * RecoveredMeanMotion() * (RecoveredSemiMajorAxis() * (1.0 + 1.5 * etasq + eeta *
(4.0 + etasq)) + 0.75 * Globals::CK2() * tsi / psisq * (4.0 + etasq)) + 0.75 * Globals::CK2() * tsi / psisq *
x3thm1_ * (8.0 + 3.0 * etasq * (8.0 + etasq))); x3thm1_ * (8.0 + 3.0 * etasq * (8.0 + etasq)));
c1_ = tle_data_0_.bstar * c2; c1_ = BStar() * c2;
a3ovk2_ = -Globals::XJ3() / Globals::CK2() * pow(Globals::AE(), 3.0); a3ovk2_ = -Globals::XJ3() / Globals::CK2() * pow(Globals::AE(), 3.0);
x1mth2_ = 1.0 - theta2; x1mth2_ = 1.0 - theta2;
c4_ = 2.0 * tle_data_0_.xno * coef1_ * aodp_ * betao2 * c4_ = 2.0 * RecoveredMeanMotion() * coef1_ * RecoveredSemiMajorAxis() * betao2 *
(eta_ * (2.0 + 0.5 * etasq) + tle_data_0_.eo * (0.5 + 2.0 * etasq) - (eta_ * (2.0 + 0.5 * etasq) + Eccentricity() * (0.5 + 2.0 * etasq) -
2.0 * Globals::CK2() * tsi / (aodp_ * psisq) * 2.0 * Globals::CK2() * tsi / (RecoveredSemiMajorAxis() * psisq) *
(-3.0 * x3thm1_ * (1.0 - 2.0 * eeta + etasq * (-3.0 * x3thm1_ * (1.0 - 2.0 * eeta + etasq *
(1.5 - 0.5 * eeta)) + 0.75 * x1mth2_ * (2.0 * etasq - eeta * (1.5 - 0.5 * eeta)) + 0.75 * x1mth2_ * (2.0 * etasq - eeta *
(1.0 + etasq)) * cos(2.0 * tle_data_0_.omega))); (1.0 + etasq)) * cos(2.0 * ArgumentPerigee())));
double theta4 = theta2 * theta2; double theta4 = theta2 * theta2;
double temp1 = 3.0 * Globals::CK2() * pinvsq * tle_data_0_.xno; double temp1 = 3.0 * Globals::CK2() * pinvsq * RecoveredMeanMotion();
double temp2 = temp1 * Globals::CK2() * pinvsq; double temp2 = temp1 * Globals::CK2() * pinvsq;
double temp3 = 1.25 * Globals::CK4() * pinvsq * pinvsq * tle_data_0_.xno; double temp3 = 1.25 * Globals::CK4() * pinvsq * pinvsq * RecoveredMeanMotion();
xmdot_ = tle_data_0_.xno + 0.5 * temp1 * betao * x3thm1_ + 0.0625 * temp2 * betao * xmdot_ = RecoveredMeanMotion() + 0.5 * temp1 * betao * x3thm1_ + 0.0625 * temp2 * betao *
(13.0 - 78.0 * theta2 + 137.0 * theta4); (13.0 - 78.0 * theta2 + 137.0 * theta4);
double x1m5th = 1.0 - 5.0 * theta2; double x1m5th = 1.0 - 5.0 * theta2;
omgdot_ = -0.5 * temp1 * x1m5th + 0.0625 * temp2 * (7.0 - 114.0 * theta2 + omgdot_ = -0.5 * temp1 * x1m5th + 0.0625 * temp2 * (7.0 - 114.0 * theta2 +
@ -192,34 +171,36 @@ void SGDP4::Initialize() {
if (!use_deep_space_) { if (!use_deep_space_) {
double c3 = 0.0; double c3 = 0.0;
if (tle_data_0_.eo > 1.0e-4) { if (Eccentricity() > 1.0e-4) {
c3 = coef * tsi * a3ovk2_ * tle_data_0_.xno * Globals::AE() * c3 = coef * tsi * a3ovk2_ * RecoveredMeanMotion() * Globals::AE() *
sinio_ / tle_data_0_.eo; sinio_ / Eccentricity();
} }
c5_ = 2.0 * coef1_ * aodp_ * betao2 * (1.0 + 2.75 * (etasq + eeta) + eeta * etasq); c5_ = 2.0 * coef1_ * RecoveredSemiMajorAxis() * betao2 * (1.0 + 2.75 * (etasq + eeta) + eeta * etasq);
omgcof_ = tle_data_0_.bstar * c3 * cos(tle_data_0_.omega); omgcof_ = BStar() * c3 * cos(ArgumentPerigee());
xmcof_ = 0.0; xmcof_ = 0.0;
if (tle_data_0_.eo > 1.0e-4) if (Eccentricity() > 1.0e-4)
xmcof_ = -Globals::TOTHRD() * coef * tle_data_0_.bstar * Globals::AE() / eeta; xmcof_ = -Globals::TOTHRD() * coef * BStar() * Globals::AE() / eeta;
delmo_ = pow(1.0 + eta_ * (cos(tle_data_0_.xmo)), 3.0); delmo_ = pow(1.0 + eta_ * (cos(MeanAnomoly())), 3.0);
sinmo_ = sin(tle_data_0_.xmo); sinmo_ = sin(MeanAnomoly());
} }
if (!use_simple_model_) { if (!use_simple_model_) {
double c1sq = c1_ * c1_; double c1sq = c1_ * c1_;
d2_ = 4.0 * aodp_ * tsi * c1sq; d2_ = 4.0 * RecoveredSemiMajorAxis() * tsi * c1sq;
double temp = d2_ * tsi * c1_ / 3.0; double temp = d2_ * tsi * c1_ / 3.0;
d3_ = (17.0 * aodp_ + s4_) * temp; d3_ = (17.0 * RecoveredSemiMajorAxis() + s4_) * temp;
d4_ = 0.5 * temp * aodp_ * tsi * (221.0 * aodp_ + 31.0 * s4_) * c1_; d4_ = 0.5 * temp * RecoveredSemiMajorAxis() * tsi * (221.0 * RecoveredSemiMajorAxis() + 31.0 * s4_) * c1_;
t3cof_ = d2_ + 2.0 * c1sq; t3cof_ = d2_ + 2.0 * c1sq;
t4cof_ = 0.25 * (3.0 * d3_ + c1_ * (12.0 * d2_ + 10.0 * c1sq)); t4cof_ = 0.25 * (3.0 * d3_ + c1_ * (12.0 * d2_ + 10.0 * c1sq));
t5cof_ = 0.2 * (3.0 * d4_ + 12.0 * c1_ * d3_ + 6.0 * d2_ * d2_ + 15.0 * t5cof_ = 0.2 * (3.0 * d4_ + 12.0 * c1_ * d3_ + 6.0 * d2_ * d2_ + 15.0 *
c1sq * (2.0 * d2_ + c1sq)); c1sq * (2.0 * d2_ + c1sq));
} else if (use_deep_space_) { } else if (use_deep_space_) {
gsto_ = tle_data_0_.epoch.ToGMST(); gsto_ = Epoch().ToGMST();
double sing = sin(ArgumentPerigee());
double cosg = cos(ArgumentPerigee());
//CALL DPINIT(EOSQ,SINIO,COSIO,BETAO,AODP,THETA2, //CALL DPINIT(EOSQ,SINIO,COSIO,BETAO,AODP,THETA2,
// SING,COSG,BETAO2,XMDOT,OMGDOT,XNODOT,XNODP) // SING,COSG,BETAO2,XMDOT,OMGDOT,XNODOT,XNODP)
} }
@ -232,14 +213,14 @@ void SGDP4::FindPosition(double tsince) {
struct TleData tle_data_tsince_; struct TleData tle_data_tsince_;
memset(&tle_data_tsince_, 0, sizeof (tle_data_tsince_)); memset(&tle_data_tsince_, 0, sizeof (tle_data_tsince_));
tle_data_tsince_.bstar = tle_data_0_.bstar; tle_data_tsince_.bstar = BStar();
tle_data_tsince_.eo = tle_data_0_.eo; tle_data_tsince_.eo = Eccentricity();
tle_data_tsince_.omega = tle_data_0_.omega; tle_data_tsince_.omega = ArgumentPerigee();
tle_data_tsince_.xincl = tle_data_0_.xincl; tle_data_tsince_.xincl = Inclination();
tle_data_tsince_.xmo = tle_data_0_.xmo; tle_data_tsince_.xmo = MeanAnomoly();
tle_data_tsince_.xno = tle_data_0_.xno; tle_data_tsince_.xno = RecoveredMeanMotion();
tle_data_tsince_.xnodeo = tle_data_0_.xnodeo; tle_data_tsince_.xnodeo = AscendingNode();
tle_data_tsince_.epoch = tle_data_0_.epoch; tle_data_tsince_.epoch = Epoch();
double xl = 0.0; double xl = 0.0;
double a = 0.0; double a = 0.0;
@ -247,8 +228,8 @@ void SGDP4::FindPosition(double tsince) {
/* /*
* update for secular gravity and atmospheric drag * update for secular gravity and atmospheric drag
*/ */
double xmdf = tle_data_0_.xmo + xmdot_ * tsince; double xmdf = MeanAnomoly() + xmdot_ * tsince;
double omgadf = tle_data_0_.omega + omgdot_ * tsince; double omgadf = ArgumentPerigee() + omgdot_ * tsince;
double xnoddf = tle_data_tsince_.xnodeo + xnodot_ * tsince; double xnoddf = tle_data_tsince_.xnodeo + xnodot_ * tsince;
double tsq = tsince * tsince; double tsq = tsince * tsince;
@ -260,13 +241,13 @@ void SGDP4::FindPosition(double tsince) {
tle_data_tsince_.omega = omgadf; tle_data_tsince_.omega = omgadf;
if (use_deep_space_) { if (use_deep_space_) {
double xn = tle_data_0_.xno; double xn = RecoveredMeanMotion();
#if 0 #if 0
CALL DPSEC(xmdf, tle_data_tsince_.omega, XNODE, tle_data_tsince_.eo, tle_data_tsince_.xincl, xn, tsince); CALL DPSEC(xmdf, tle_data_tsince_.omega, XNODE, tle_data_tsince_.eo, tle_data_tsince_.xincl, xn, tsince);
#endif #endif
a = pow(Globals::XKE() / xn, Globals::TOTHRD()) * pow(tempa, 2.0); a = pow(Globals::XKE() / xn, Globals::TOTHRD()) * pow(tempa, 2.0);
tle_data_tsince_.eo -= tempe; tle_data_tsince_.eo -= tempe;
double xmam = xmdf + tle_data_0_.xno * templ; double xmam = xmdf + RecoveredMeanMotion() * templ;
#if 0 #if 0
CALL DPPER(tle_data_tsince_.eo, tle_data_tsince_.xincl, tle_data_tsince_.omega, tle_data_tsince_.xnodeo, xmam); CALL DPPER(tle_data_tsince_.eo, tle_data_tsince_.xincl, tle_data_tsince_.omega, tle_data_tsince_.xnodeo, xmam);
#endif #endif
@ -305,9 +286,9 @@ void SGDP4::FindPosition(double tsince) {
tempe += tle_data_tsince_.bstar * c5_ * (sin(xmp) - sinmo_); tempe += tle_data_tsince_.bstar * c5_ * (sin(xmp) - sinmo_);
templ += t3cof_ * tcube + tfour * (t4cof_ + tsince * t5cof_); templ += t3cof_ * tcube + tfour * (t4cof_ + tsince * t5cof_);
} }
a = aodp_ * pow(tempa, 2.0); a = RecoveredSemiMajorAxis() * pow(tempa, 2.0);
tle_data_tsince_.eo = tle_data_0_.eo - tempe; tle_data_tsince_.eo = Eccentricity() - tempe;
xl = xmp + tle_data_tsince_.omega + xnode + tle_data_0_.xno * templ; xl = xmp + tle_data_tsince_.omega + xnode + RecoveredMeanMotion() * templ;
} }
double beta = sqrt(1.0 - tle_data_tsince_.eo * tle_data_tsince_.eo); double beta = sqrt(1.0 - tle_data_tsince_.eo * tle_data_tsince_.eo);

22
SGDP4.h
View File

@ -24,15 +24,12 @@ public:
}; };
private: private:
void Initialize(); void Initialize(const double& theta2, const double& betao2, const double& betao);
bool first_run_; bool first_run_;
struct TleData tle_data_0_;
double cosio_; double cosio_;
double sinio_; double sinio_;
double aodp_;
double x3thm1_; double x3thm1_;
double eta_; double eta_;
@ -121,7 +118,7 @@ private:
* AODP * AODP
*/ */
double RecoveredSemiMajorAxis() const { double RecoveredSemiMajorAxis() const {
return recovered_semi_major_axis; return recovered_semi_major_axis_;
} }
/* /*
@ -131,6 +128,17 @@ private:
return recovered_mean_motion_; return recovered_mean_motion_;
} }
/*
* PERIGE
*/
double Perigee() const {
return perigee_;
}
double Period() const {
return period_;
}
/* /*
* EPOCH * EPOCH
*/ */
@ -145,8 +153,10 @@ private:
double inclination_; double inclination_;
double mean_motion_; double mean_motion_;
double bstar_; double bstar_;
double recovered_semi_major_axis; double recovered_semi_major_axis_;
double recovered_mean_motion_; double recovered_mean_motion_;
double perigee_;
double period_;
Julian epoch_; Julian epoch_;
}; };

13
Tle.cpp
View File

@ -192,15 +192,14 @@ void Tle::Initialize() {
fields_[fld].second = atof(fields_[fld].first.c_str()); fields_[fld].second = atof(fields_[fld].first.c_str());
} }
int epochYear = (int) GetField(Tle::FLD_EPOCHYEAR); int year = static_cast<int> (GetField(Tle::FLD_EPOCHYEAR));
double epochDay = GetField(Tle::FLD_EPOCHDAY); if (year < 57)
year += 2000;
if (epochYear < 57)
epochYear += 2000;
else else
epochYear += 1900; year += 1900;
double day = GetField(Tle::FLD_EPOCHDAY);
date_ = Julian(epochYear, epochDay); date_ = Julian(year, day);
} }
/* /*