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Create function to compute perturbed values.

feature/19
Daniel Warner 2018-08-27 12:29:44 +01:00 committed by Daniel Warner
parent 7b08f419d2
commit adc1c36a5b
2 changed files with 61 additions and 39 deletions
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92
libsgp4/SGP4.cc
View File

@ -61,10 +61,16 @@ void SGP4::Initialise()
throw SatelliteException("Inclination out of range");
}
common_consts_.cosio = cos(elements_.Inclination());
common_consts_.sinio = sin(elements_.Inclination());
RecomputeConstants(elements_.Inclination(),
common_consts_.sinio,
common_consts_.cosio,
common_consts_.x3thm1,
common_consts_.x1mth2,
common_consts_.x7thm1,
common_consts_.xlcof,
common_consts_.aycof);
const double theta2 = common_consts_.cosio * common_consts_.cosio;
common_consts_.x3thm1 = 3.0 * theta2 - 1.0;
const double eosq = elements_.Eccentricity() * elements_.Eccentricity();
const double betao2 = 1.0 - eosq;
const double betao = sqrt(betao2);
@ -127,8 +133,6 @@ void SGP4::Initialise()
+ 0.75 * kCK2 * tsi / psisq * common_consts_.x3thm1
* (8.0 + 3.0 * etasq * (8.0 + etasq)));
common_consts_.c1 = elements_.BStar() * c2;
common_consts_.a3ovk2 = -kXJ3 / kCK2 * kAE * kAE * kAE;
common_consts_.x1mth2 = 1.0 - theta2;
common_consts_.c4 = 2.0 * elements_.RecoveredMeanMotion()
* coef1 * elements_.RecoveredSemiMajorAxis() * betao2
* (common_consts_.eta * (2.0 + 0.5 * etasq) + elements_.Eccentricity()
@ -155,18 +159,6 @@ void SGP4::Initialise()
common_consts_.xnodcf = 3.5 * betao2 * xhdot1 * common_consts_.c1;
common_consts_.t2cof = 1.5 * common_consts_.c1;
if (fabs(common_consts_.cosio + 1.0) > 1.5e-12)
{
common_consts_.xlcof = 0.125 * common_consts_.a3ovk2 * common_consts_.sinio * (3.0 + 5.0 * common_consts_.cosio) / (1.0 + common_consts_.cosio);
}
else
{
common_consts_.xlcof = 0.125 * common_consts_.a3ovk2 * common_consts_.sinio * (3.0 + 5.0 * common_consts_.cosio) / 1.5e-12;
}
common_consts_.aycof = 0.25 * common_consts_.a3ovk2 * common_consts_.sinio;
common_consts_.x7thm1 = 7.0 * theta2 - 1.0;
if (use_deep_space_)
{
deepspace_consts_.gsto = elements_.Epoch().ToGreenwichSiderealTime();
@ -316,29 +308,21 @@ Eci SGP4::FindPositionSDP4(double tsince) const
/*
* re-compute the perturbed values
*/
const double perturbed_sinio = sin(xincl);
const double perturbed_cosio = cos(xincl);
const double perturbed_theta2 = perturbed_cosio * perturbed_cosio;
const double perturbed_x3thm1 = 3.0 * perturbed_theta2 - 1.0;
const double perturbed_x1mth2 = 1.0 - perturbed_theta2;
const double perturbed_x7thm1 = 7.0 * perturbed_theta2 - 1.0;
double perturbed_sinio;
double perturbed_cosio;
double perturbed_x3thm1;
double perturbed_x1mth2;
double perturbed_x7thm1;
double perturbed_xlcof;
if (fabs(perturbed_cosio + 1.0) > 1.5e-12)
{
perturbed_xlcof = 0.125 * common_consts_.a3ovk2 * perturbed_sinio
* (3.0 + 5.0 * perturbed_cosio) / (1.0 + perturbed_cosio);
}
else
{
perturbed_xlcof = 0.125 * common_consts_.a3ovk2 * perturbed_sinio
* (3.0 + 5.0 * perturbed_cosio) / 1.5e-12;
}
const double perturbed_aycof = 0.25 * common_consts_.a3ovk2
* perturbed_sinio;
double perturbed_aycof;
RecomputeConstants(xincl,
perturbed_sinio,
perturbed_cosio,
perturbed_x3thm1,
perturbed_x1mth2,
perturbed_x7thm1,
perturbed_xlcof,
perturbed_aycof);
/*
* using calculated values, find position and velocity
@ -359,6 +343,36 @@ Eci SGP4::FindPositionSDP4(double tsince) const
perturbed_sinio);
}
void SGP4::RecomputeConstants(const double xincl,
double& sinio,
double& cosio,
double& x3thm1,
double& x1mth2,
double& x7thm1,
double& xlcof,
double& aycof)
{
sinio = sin(xincl);
cosio = cos(xincl);
const double theta2 = cosio * cosio;
x3thm1 = 3.0 * theta2 - 1.0;
x1mth2 = 1.0 - theta2;
x7thm1 = 7.0 * theta2 - 1.0;
if (fabs(cosio + 1.0) > 1.5e-12)
{
xlcof = 0.125 * kA3OVK2 * sinio * (3.0 + 5.0 * cosio) / (1.0 + cosio);
}
else
{
xlcof = 0.125 * kA3OVK2 * sinio * (3.0 + 5.0 * cosio) / 1.5e-12;
}
aycof = 0.25 * kA3OVK2 * sinio;
}
Eci SGP4::FindPositionSGP4(double tsince) const
{
/*

8
libsgp4/SGP4.h
View File

@ -189,6 +189,14 @@ private:
};
void Initialise();
static void RecomputeConstants(const double xincl,
double& sinio,
double& cosio,
double& x3thm1,
double& x1mth2,
double& x7thm1,
double& xlcof,
double& aycof);
Eci FindPositionSDP4(const double tsince) const;
Eci FindPositionSGP4(double tsince) const;
Eci CalculateFinalPositionVelocity(