org.orekit.estimation.measurements

Class Position

java.lang.Object

org.orekit.estimation.measurements.AbstractMeasurement<Position>

org.orekit.estimation.measurements.Position

All Implemented Interfaces:

Comparable<ComparableMeasurement>, ComparableMeasurement, ObservedMeasurement<Position>, TimeStamped

public class Position
extends AbstractMeasurement<Position>

Class modeling a position only measurement.

For position-velocity measurement see PV.

Since:

9.3

Author:

Luc Maisonobe

See Also:

PV

Constructor Summary

Constructors

Constructor and Description
Position(AbsoluteDate date, Vector3D position, double[][] covarianceMatrix, double baseWeight, ObservableSatellite satellite) Constructor with full covariance matrix and all inputs.
Position(AbsoluteDate date, Vector3D position, double[] sigmaPosition, double baseWeight, ObservableSatellite satellite) Constructor with one vector for the standard deviation.
Position(AbsoluteDate date, Vector3D position, double sigmaPosition, double baseWeight, ObservableSatellite satellite) Constructor with one double for the standard deviation.

Method Summary

Modifier and Type	Method and Description
double[][]	getCorrelationCoefficientsMatrix() Get the correlation coefficients matrix.
double[][]	getCovarianceMatrix() Get the covariance matrix.
Vector3D	getPosition() Get the position.
protected EstimatedMeasurement<Position>	theoreticalEvaluation(int iteration, int evaluation, SpacecraftState[] states) Estimate the theoretical value.

Methods inherited from class org.orekit.estimation.measurements.AbstractMeasurement

addModifier, addParameterDriver, estimate, getBaseWeight, getCoordinates, getDate, getDimension, getModifiers, getObservedValue, getParametersDrivers, getSatellites, getTheoreticalStandardDeviation, isEnabled, setEnabled, signalTimeOfFlight, signalTimeOfFlight

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.estimation.measurements.ComparableMeasurement

compareTo

Constructor Detail

Position

public Position(AbsoluteDate date,
                Vector3D position,
                double sigmaPosition,
                double baseWeight,
                ObservableSatellite satellite)

Constructor with one double for the standard deviation.

The double is the position's standard deviation, common to the 3 position's components.

The measurement must be in the orbit propagation frame.

Parameters:

date - date of the measurement

position - position

sigmaPosition - theoretical standard deviation on position components

baseWeight - base weight

satellite - satellite related to this measurement

Since:

9.3

Position

public Position(AbsoluteDate date,
                Vector3D position,
                double[] sigmaPosition,
                double baseWeight,
                ObservableSatellite satellite)

Constructor with one vector for the standard deviation.

The 3-sized vector represents the square root of the diagonal elements of the covariance matrix.

The measurement must be in the orbit propagation frame.

Parameters:

date - date of the measurement

position - position

sigmaPosition - 3-sized vector of the standard deviations of the position

baseWeight - base weight

satellite - satellite related to this measurement

Since:

9.3

Position

public Position(AbsoluteDate date,
                Vector3D position,
                double[][] covarianceMatrix,
                double baseWeight,
                ObservableSatellite satellite)

Constructor with full covariance matrix and all inputs.

The fact that the covariance matrix is symmetric and positive definite is not checked.

The measurement must be in the orbit propagation frame.

Parameters:

date - date of the measurement

position - position

covarianceMatrix - 6x6 covariance matrix of the PV measurement

baseWeight - base weight

satellite - satellite related to this measurement

Since:

9.3

Method Detail

getPosition

public Vector3D getPosition()

Get the position.

Returns:

position

getCovarianceMatrix

public double[][] getCovarianceMatrix()

Get the covariance matrix.

Returns:

the covariance matrix

getCorrelationCoefficientsMatrix

public double[][] getCorrelationCoefficientsMatrix()

Get the correlation coefficients matrix.

This is the 3x3 matrix M such that:

Mij = Pij/(σi.σj)

Where:

• P is the covariance matrix
• σi is the i-th standard deviation (σi² = Pii)

Returns:

the correlation coefficient matrix (3x3)

theoreticalEvaluation

protected EstimatedMeasurement<Position> theoreticalEvaluation(int iteration,
                                                               int evaluation,
                                                               SpacecraftState[] states)

Estimate the theoretical value.

The theoretical value does not have any modifiers applied.

Specified by:

theoreticalEvaluation in class AbstractMeasurement<Position>

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

Returns:

theoretical value

See Also:

AbstractMeasurement.estimate(int, int, SpacecraftState[])