org.orekit.propagation.analytical.tle
Class AbstractTLEFitter

java.lang.Object
  org.orekit.propagation.analytical.tle.AbstractTLEFitter

Direct Known Subclasses:

DifferentialOrbitConverter, LevenbergMarquardtOrbitConverter

public abstract class AbstractTLEFitter
extends Object

Abstract class for TLE/Orbit fitting.

Two-Line Elements are tightly linked to the SGP4/SDP4 propagation models. They cannot be used with other models and do not represent osculating orbits. When conversion is needed, the model must be considered and conversion must be done by some fitting method on a sufficient time range.

This base class factor the common code for such conversions. Different implementations correspond to different fitting algorithms.

Since:

6.0

Author:

Rocca

Constructor Summary

protected

AbstractTLEFitter(int satelliteNumber, char classification, int launchYear, int launchNumber, String launchPiece, int elementNumber, int revolutionNumberAtEpoch) Simple constructor.

Method Summary

protected abstract double[]	fit(double[] initial) Find the TLE elements that minimize the mean square error for a sample of states.
protected double	getPositionTolerance() Get the desired position tolerance.
protected DifferentiableMultivariateVectorFunction	getPVFunction() Get the function computing position/velocity at sample points.
protected double[]	getResiduals(double[] parameters) Get the residuals for a given position/velocity/B* parameters set.
double	getRMS() Get Root Mean Square of the fitting.
protected double	getRMS(double[] parameters) Get the RMS for a given position/velocity/B* parameters set.
protected double[]	getTarget() Get the position/velocity target at sample points.
TLE	getTLE() Get the fitted Two-Lines Elements.
protected TLE	getTLE(double[] parameters) Get the TLE for a given position/velocity/B* parameters set.
protected double[]	getWeight() Get the weights for residuals.
TLE	toTLE(List<SpacecraftState> states, double positionTolerance, boolean positionOnly, boolean withBStar) Find the TLE elements that minimize the mean square error for a sample of states.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractTLEFitter

protected AbstractTLEFitter(int satelliteNumber,
                            char classification,
                            int launchYear,
                            int launchNumber,
                            String launchPiece,
                            int elementNumber,
                            int revolutionNumberAtEpoch)

Simple constructor.

Parameters:

satelliteNumber - satellite number

classification - classification (U for unclassified)

launchYear - launch year (all digits)

launchNumber - launch number

launchPiece - launch piece

elementNumber - element number

revolutionNumberAtEpoch - revolution number at epoch

Method Detail

toTLE

public TLE toTLE(List<SpacecraftState> states,
                 double positionTolerance,
                 boolean positionOnly,
                 boolean withBStar)
          throws OrekitException,
                 MaxCountExceededException

Find the TLE elements that minimize the mean square error for a sample of states.

Parameters:

states - spacecraft states sample to fit

positionTolerance - desired position tolerance

positionOnly - if true, consider only position data otherwise both position and velocity are used

withBStar - if true, the B* coefficient must be evaluated too, otherwise it will be forced to 0

Returns:

fitted TLE

Throws:

OrekitException - if TLE cannot be computed

MaxCountExceededException - if maximal number of iterations is exceeded

See Also:

getTLE(), getRMS()

getTLE

public TLE getTLE()

Get the fitted Two-Lines Elements.

Returns:

fitted Two-Lines Elements

See Also:

toTLE(List, double, boolean, boolean)

getRMS

public double getRMS()

Get Root Mean Square of the fitting.

Returns:

rms

See Also:

toTLE(List, double, boolean, boolean)

fit

protected abstract double[] fit(double[] initial)
                         throws OrekitException,
                                MaxCountExceededException

Find the TLE elements that minimize the mean square error for a sample of states.

Parameters:

initial - initial estimation parameters (position, velocity and B* if estimated)

Returns:

fitted parameters

Throws:

OrekitException - if TLE cannot be computed

MaxCountExceededException - if maximal number of iterations is exceeded

getTLE

protected TLE getTLE(double[] parameters)

Get the TLE for a given position/velocity/B* parameters set.

Parameters:

parameters - position/velocity/B* parameters set

Returns:

TLE

getTarget

protected double[] getTarget()

Get the position/velocity target at sample points.

Returns:

position/velocity target at sample points

getWeight

protected double[] getWeight()

Get the weights for residuals.

Returns:

weights for residuals

getResiduals

protected double[] getResiduals(double[] parameters)
                         throws OrekitException

Get the residuals for a given position/velocity/B* parameters set.

Parameters:

parameters - position/velocity/B* parameters set

Returns:

residuals

Throws:

OrekitException - if position/velocity cannot be computed at some date

See Also:

getRMS(double[])

getRMS

protected double getRMS(double[] parameters)
                 throws OrekitException

Get the RMS for a given position/velocity/B* parameters set.

Parameters:

parameters - position/velocity/B* parameters set

Returns:

RMS

Throws:

OrekitException - if position/velocity cannot be computed at some date

See Also:

getResiduals(double[])

getPVFunction

protected DifferentiableMultivariateVectorFunction getPVFunction()

Get the function computing position/velocity at sample points.

Returns:

function computing position/velocity at sample points

getPositionTolerance

protected double getPositionTolerance()

Get the desired position tolerance.

Returns:

position tolerance