org.orekit.estimation.measurements

Class AbstractMeasurement<T extends ObservedMeasurement<T>>

java.lang.Object

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

Type Parameters:

T - the type of the measurement

All Implemented Interfaces:

ObservedMeasurement<T>, TimeStamped

Direct Known Subclasses:

AngularAzEl, AngularRaDec, InterSatellitesRange, PV, Range, RangeRate, TurnAroundRange

public abstract class AbstractMeasurement<T extends ObservedMeasurement<T>>
extends Object
implements ObservedMeasurement<T>

Abstract class handling measurements boilerplate.

Since:

8.0

Author:

Luc Maisonobe

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMeasurement(AbsoluteDate date, double[] observed, double[] sigma, double[] baseWeight, List<Integer> propagatorsIndices, ParameterDriver... supportedParameters) Simple constructor, for multi-dimensional measurements.
protected	AbstractMeasurement(AbsoluteDate date, double observed, double sigma, double baseWeight, List<Integer> propagatorsIndices, ParameterDriver... supportedParameters) Simple constructor for mono-dimensional measurements.

Method Summary

Modifier and Type	Method and Description
void	addModifier(EstimationModifier<T> modifier) Add a modifier.
EstimatedMeasurement<T>	estimate(int iteration, int evaluation, SpacecraftState[] states) Estimate the theoretical value of the measurement.
double[]	getBaseWeight() Get the base weight associated with the measurement
static TimeStampedFieldPVCoordinates<DerivativeStructure>	getCoordinates(SpacecraftState state, int firstDerivative, DSFactory factory) Get Cartesian coordinates as derivatives.
AbsoluteDate	getDate() Get the date.
int	getDimension() Get the dimension of the measurement.
List<EstimationModifier<T>>	getModifiers() Get the modifiers that apply to a measurement.
double[]	getObservedValue() Get the observed value.
List<ParameterDriver>	getParametersDrivers() Get the drivers for this measurement parameters, including its modifiers parameters.
List<Integer>	getPropagatorsIndices() Get the indices of the propagators related to this measurement.
double[]	getTheoreticalStandardDeviation() Get the theoretical standard deviation.
boolean	isEnabled() Check if a measurement is enabled.
void	setEnabled(boolean enabled) Enable or disable a measurement.
static <T extends RealFieldElement<T>> T	signalTimeOfFlight(TimeStampedFieldPVCoordinates<T> adjustableEmitterPV, FieldVector3D<T> receiverPosition, FieldAbsoluteDate<T> signalArrivalDate) Compute propagation delay on a link leg (typically downlink or uplink).
static double	signalTimeOfFlight(TimeStampedPVCoordinates adjustableEmitterPV, Vector3D receiverPosition, AbsoluteDate signalArrivalDate) Compute propagation delay on a link leg (typically downlink or uplink).
protected abstract EstimatedMeasurement<T>	theoreticalEvaluation(int iteration, int evaluation, SpacecraftState[] states) Estimate the theoretical value.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractMeasurement

protected AbstractMeasurement(AbsoluteDate date,
                              double observed,
                              double sigma,
                              double baseWeight,
                              List<Integer> propagatorsIndices,
                              ParameterDriver... supportedParameters)

Simple constructor for mono-dimensional measurements.

At construction, a measurement is enabled.

Parameters:

date - date of the measurement

observed - observed value

sigma - theoretical standard deviation

baseWeight - base weight

propagatorsIndices - indices of the propagators related to this measurement

supportedParameters - supported parameters

AbstractMeasurement

protected AbstractMeasurement(AbsoluteDate date,
                              double[] observed,
                              double[] sigma,
                              double[] baseWeight,
                              List<Integer> propagatorsIndices,
                              ParameterDriver... supportedParameters)

Simple constructor, for multi-dimensional measurements.

At construction, a measurement is enabled.

Parameters:

date - date of the measurement

observed - observed value

sigma - theoretical standard deviation

baseWeight - base weight

propagatorsIndices - indices of the propagators related to this measurement

supportedParameters - supported parameters

Method Detail

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the drivers for this measurement parameters, including its modifiers parameters.

Specified by:

getParametersDrivers in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

drivers for this measurement parameters, including its modifiers parameters

setEnabled

public void setEnabled(boolean enabled)

Enable or disable a measurement.

Disabling a measurement allow to not consider it at one stage of the orbit determination (for example when it appears to be an outlier as per current estimated covariance).

Specified by:

setEnabled in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Parameters:

enabled - if true the measurement will be enabled, otherwise it will be disabled

isEnabled

public boolean isEnabled()

Check if a measurement is enabled.

Specified by:

isEnabled in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

true if the measurement is enabled

getDimension

public int getDimension()

Get the dimension of the measurement.

Dimension is the size of the array containing the value. It will be one for a scalar measurement like a range or range-rate, but 6 for a position-velocity measurement.

Specified by:

getDimension in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

dimension of the measurement

getTheoreticalStandardDeviation

public double[] getTheoreticalStandardDeviation()

Get the theoretical standard deviation.

The theoretical standard deviation is a theoretical value used for normalizing the residuals. It acts as a weighting factor to mix appropriately measurements with different units and different accuracy. The value has the same dimension as the measurement itself (i.e. when a residual is divided by this value, it becomes dimensionless).

Specified by:

getTheoreticalStandardDeviation in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

expected standard deviation

See Also:

ObservedMeasurement.getBaseWeight()

getBaseWeight

public double[] getBaseWeight()

Get the base weight associated with the measurement

The base weight is used on residuals already normalized thanks to ObservedMeasurement.getTheoreticalStandardDeviation() to increase or decrease relative effect of some measurements with respect to other measurements. It is a dimensionless value, typically between 0 and 1 (but it can really have any non-negative value).

Specified by:

getBaseWeight in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

base weight

See Also:

ObservedMeasurement.getTheoreticalStandardDeviation(), EstimatedMeasurement.getCurrentWeight()

getPropagatorsIndices

public List<Integer> getPropagatorsIndices()

Get the indices of the propagators related to this measurement.

The propagators are indexed starting from 0 and ordered according to the order of the propagators builders in the orbit determination engine used.

Specified by:

getPropagatorsIndices in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

indices of the propagators related to this measurement

theoreticalEvaluation

protected abstract EstimatedMeasurement<T> theoreticalEvaluation(int iteration,
                                                                 int evaluation,
                                                                 SpacecraftState[] states)
                                                          throws OrekitException

Estimate the theoretical value.

The theoretical value does not have any modifiers applied.

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

Returns:

theoretical value

Throws:

OrekitException - if value cannot be computed

See Also:

estimate(int, int, SpacecraftState[])

estimate

public EstimatedMeasurement<T> estimate(int iteration,
                                        int evaluation,
                                        SpacecraftState[] states)
                                 throws OrekitException

Estimate the theoretical value of the measurement.

The estimated value is the combination of the raw estimated value and all the modifiers that apply to the measurement.

Specified by:

estimate in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Parameters:

iteration - iteration number

evaluation - evaluations number

states - orbital states at measurement date

Returns:

estimated measurement

Throws:

OrekitException - if value cannot be computed

getDate

public AbsoluteDate getDate()

Get the date.

Specified by:

getDate in interface TimeStamped

Returns:

date attached to the object

getObservedValue

public double[] getObservedValue()

Get the observed value.

The observed value is the value that was measured by the instrument.

Specified by:

getObservedValue in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

observed value (array of size ObservedMeasurement.getDimension()

addModifier

public void addModifier(EstimationModifier<T> modifier)
                 throws OrekitException

Add a modifier.

The modifiers are applied in the order in which they are added in order to estimate the measurement.

Specified by:

addModifier in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Parameters:

modifier - modifier to add

Throws:

OrekitException - if there is a conflict between measurement and modifiers parameters

See Also:

ObservedMeasurement.getModifiers()

getModifiers

public List<EstimationModifier<T>> getModifiers()

Get the modifiers that apply to a measurement.

Specified by:

getModifiers in interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Returns:

modifiers that apply to a measurement

See Also:

ObservedMeasurement.addModifier(EstimationModifier)

signalTimeOfFlight

public static double signalTimeOfFlight(TimeStampedPVCoordinates adjustableEmitterPV,
                                        Vector3D receiverPosition,
                                        AbsoluteDate signalArrivalDate)

Compute propagation delay on a link leg (typically downlink or uplink).

Parameters:

adjustableEmitterPV - position/velocity of emitter that may be adjusted

receiverPosition - fixed position of receiver at signalArrivalDate, in the same frame as adjustableEmitterPV

signalArrivalDate - date at which the signal arrives to receiver

Returns:

positive delay between signal emission and signal reception dates

signalTimeOfFlight

public static <T extends RealFieldElement<T>> T signalTimeOfFlight(TimeStampedFieldPVCoordinates<T> adjustableEmitterPV,
                                                                   FieldVector3D<T> receiverPosition,
                                                                   FieldAbsoluteDate<T> signalArrivalDate)

Compute propagation delay on a link leg (typically downlink or uplink).

Type Parameters:

T - the type of the components

Parameters:

adjustableEmitterPV - position/velocity of emitter that may be adjusted

receiverPosition - fixed position of receiver at signalArrivalDate, in the same frame as adjustableEmitterPV

signalArrivalDate - date at which the signal arrives to receiver

Returns:

positive delay between signal emission and signal reception dates

getCoordinates

public static TimeStampedFieldPVCoordinates<DerivativeStructure> getCoordinates(SpacecraftState state,
                                                                                int firstDerivative,
                                                                                DSFactory factory)

Get Cartesian coordinates as derivatives.

The position will correspond to variables firstDerivative, firstDerivative + 1 and firstDerivative + 2. The velocity will correspond to variables firstDerivative + 3, firstDerivative + 4 and firstDerivative + 5. The acceleration will corredpon to constants.

Parameters:

state - state of the satellite considered

firstDerivative - index of the first derivative

factory - factory for building the derivatives

Returns:

Cartesian coordinates as derivatives