Package org.orekit.propagation.analytical.tle.generation

Class TleGenerationAlgorithm

java.lang.Object

org.orekit.orbits.AbstractOrbitalParameterFactory<TLE>

org.orekit.propagation.analytical.tle.generation.TleGenerationAlgorithm

All Implemented Interfaces:

Cloneable, OrbitalParameterFactory<TLE>

Direct Known Subclasses:

FixedPointTleGenerationAlgorithm, LeastSquaresTleGenerationAlgorithm

public abstract class TleGenerationAlgorithm
extends AbstractOrbitalParameterFactory<TLE>

Base class for generating a TLE.

Since:

12.0

Author:

Bryan Cazabonne

Field Summary

Fields

Modifier and Type	Field	Description
static final String	B_STAR	Parameter name for B* coefficient.
static final double	B_STAR_SCALE	B* scaling factor.
static final String	ECCENTRICITY	Name for eccentricity.
static final String	INCLINATION	Name for inclination.
static final String	MEAN_ANOM	Name for mean anomaly.
static final String	MEAN_MOTION	Name for mean motion.
static final String	PERIAPSIS_ARGUMENT	Name for periapsis argument.
static final String	RAAN	Name for right ascension of ascending node.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	TleGenerationAlgorithm(TLE templateTLE, Frame teme, OsculatingToMeanConverter converter)	Default constructor.

Method Summary

Modifier and Type	Method	Description
TleGenerationAlgorithm	clone()
TLE	createFromDrivers()	Create orbital parameters from current drivers values.
<T extends CalculusFieldElement<T>> FieldTLE<T>	generate(FieldSpacecraftState<T> state, FieldTLE<T> newTemplateTLE)	Generate a TLE from a given spacecraft state and a template TLE.
TLE	generate(SpacecraftState state, TLE newTemplateTLE)	Generate a TLE from a given spacecraft state and a template TLE.
protected double	getBStar()	Get the current B-star value.
OsculatingToMeanConverter	getConverter()	Get the osculating to mean orbit converter.
RealMatrix	getJacobianWrtParameters()	Get the Jacobian of the Cartesian coordinates with respect to the orbital parameters.
RealMatrix	getJacobianWrtParameters(TLE tle)	Get the Jacobian of the Cartesian coordinates with respect to the orbital elements of a TLE.
ParameterDriversList	getNonKeplerianParametersDrivers()	Get the drivers for additional drivers for non-Keplerian motion.
TLE	getTemplateTLE()	Get the template TLE.
protected double[]	toArray(Orbit orbit)	Convert an input into an array suitable to feed orbital parameters drivers.

Methods inherited from class org.orekit.orbits.AbstractOrbitalParameterFactory

getDate, getFrame, getJacobianWrtCartesian, getMu, getOrbitalParametersDrivers, getOrbitType, getPositionAngleType, reset, setDate, setFrame, setMu, setPositionAngleType

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

MEAN_MOTION

public static final String MEAN_MOTION

Name for mean motion.

See Also:

• Constant Field Values

ECCENTRICITY

public static final String ECCENTRICITY

Name for eccentricity.

See Also:

• Constant Field Values

INCLINATION

public static final String INCLINATION

Name for inclination.

See Also:

• Constant Field Values

PERIAPSIS_ARGUMENT

public static final String PERIAPSIS_ARGUMENT

Name for periapsis argument.

See Also:

• Constant Field Values

RAAN

public static final String RAAN

Name for right ascension of ascending node.

See Also:

• Constant Field Values

MEAN_ANOM

public static final String MEAN_ANOM

Name for mean anomaly.

See Also:

• Constant Field Values

B_STAR

public static final String B_STAR

Parameter name for B* coefficient.

See Also:

• Constant Field Values

B_STAR_SCALE

public static final double B_STAR_SCALE

B* scaling factor.

We use a power of 2 to avoid numeric noise introduction in the multiplications/divisions sequences.

Constructor Details

TleGenerationAlgorithm

protected TleGenerationAlgorithm(TLE templateTLE,
 Frame teme,
 OsculatingToMeanConverter converter)

Default constructor.

Parameters:

templateTLE - template TLE

teme - teme frame

converter - osculating to mean orbit converter

Method Details

getTemplateTLE

public TLE getTemplateTLE()

Get the template TLE.

Returns:

template TLE

getConverter

public OsculatingToMeanConverter getConverter()

Get the osculating to mean orbit converter.

Returns:

osculating to mean orbit converter

Since:

14.0

getNonKeplerianParametersDrivers

public ParameterDriversList getNonKeplerianParametersDrivers()

Get the drivers for additional drivers for non-Keplerian motion.

Specified by:

getNonKeplerianParametersDrivers in interface OrbitalParameterFactory<TLE>

Overrides:

getNonKeplerianParametersDrivers in class AbstractOrbitalParameterFactory<TLE>

Returns:

drivers for non-Keplerian motion

toArray

protected double[] toArray(Orbit orbit)

Convert an input into an array suitable to feed orbital parameters drivers.

Specified by:

toArray in class AbstractOrbitalParameterFactory<TLE>

Parameters:

orbit - orbit to convert

Returns:

arrays corresponding to orbit

createFromDrivers

public TLE createFromDrivers()

Create orbital parameters from current drivers values.

Returns:

created orbital parameters

getJacobianWrtParameters

public RealMatrix getJacobianWrtParameters()

Get the Jacobian of the Cartesian coordinates with respect to the orbital parameters.

The Jacobian is evaluated at the current drivers values, at the factory date and in the factory frame.

The TLE orbital elements are related to the Cartesian coordinates by the SGP4/SDP4 model itself, which has no closed-form derivatives, so the Jacobian is obtained by automatic differentiation: the six elements of the TLE built from the current drivers are turned into Gradient variables, and the resulting TLE is evaluated at its own epoch.

Returns:

jacobian matrix dC/dB, where C are the Cartesian coordinates and B the orbital parameters this factory is built upon

getJacobianWrtParameters

public RealMatrix getJacobianWrtParameters(TLE tle)

Get the Jacobian of the Cartesian coordinates with respect to the orbital elements of a TLE.

The TLE orbital elements are related to the Cartesian coordinates by the SGP4/SDP4 model itself, which has no closed-form derivatives, so the Jacobian is obtained by automatic differentiation: the six orbital elements are turned into Gradient variables and the TLE is evaluated at its own epoch. All the remaining data (identification, mean motion derivatives, B*) are held constant.

Parameters:

tle - TLE holding the orbital elements the Jacobian is computed with respect to

Returns:

jacobian matrix dC/dB, at the TLE epoch and in the TEME frame

getBStar

protected double getBStar()

Get the current B-star value.

Returns:

current B-star value

generate

public TLE generate(SpacecraftState state,
 TLE newTemplateTLE)

Generate a TLE from a given spacecraft state and a template TLE.

The template TLE is only used to get identifiers like satellite number, launch year, etc. In other words, the keplerian elements contained in the generated TLE are based on the provided state and not the template TLE.

Parameters:

state - spacecraft state

newTemplateTLE - template TLE

Returns:

a TLE corresponding to the given state

generate

public <T extends CalculusFieldElement<T>>
FieldTLE<T> generate(FieldSpacecraftState<T> state,
 FieldTLE<T> newTemplateTLE)

Generate a TLE from a given spacecraft state and a template TLE.

The template TLE is only used to get identifiers like satellite number, launch year, etc. In other words, the keplerian elements contained in the generated TLE are based on the provided state and not the template TLE.

Type Parameters:

T - type of the elements

Parameters:

state - spacecraft state

newTemplateTLE - template TLE

Returns:

a TLE corresponding to the given state

clone

public TleGenerationAlgorithm clone()

Overrides:

clone in class AbstractOrbitalParameterFactory<TLE>