org.orekit.estimation.measurements

Interface ObservedMeasurement<T extends ObservedMeasurement<T>>

Type Parameters:

T - the type of the measurement

All Superinterfaces:

TimeStamped

All Known Implementing Classes:

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

public interface ObservedMeasurement<T extends ObservedMeasurement<T>>
extends TimeStamped

Interface for measurements used for orbit determination.

The most important methods of this interface allow to:

• get the observed value,
• estimate the theoretical value of a measurement,
• compute the corresponding partial derivatives (with respect to state and parameters)

The estimated theoretical values can be modified by registering one or several EstimationModifier objects. These objects will manage notions like tropospheric delays, biases, ...

Since:

8.0

Author:

Luc Maisonobe

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
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.

Methods inherited from interface org.orekit.time.TimeStamped

getDate

Method Detail

setEnabled

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).

Parameters:

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

isEnabled

boolean isEnabled()

Check if a measurement is enabled.

Returns:

true if the measurement is enabled

getDimension

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.

Returns:

dimension of the measurement

getTheoreticalStandardDeviation

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).

Returns:

expected standard deviation

See Also:

getBaseWeight()

getBaseWeight

double[] getBaseWeight()

Get the base weight associated with the measurement

The base weight is used on residuals already normalized thanks to 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).

Returns:

base weight

See Also:

getTheoreticalStandardDeviation(), EstimatedMeasurement.getCurrentWeight()

getObservedValue

double[] getObservedValue()

Get the observed value.

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

Returns:

observed value (array of size getDimension()

addModifier

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.

Parameters:

modifier - modifier to add

Throws:

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

See Also:

getModifiers()

getModifiers

List<EstimationModifier<T>> getModifiers()

Get the modifiers that apply to a measurement.

Returns:

modifiers that apply to a measurement

See Also:

addModifier(EstimationModifier)

getParametersDrivers

List<ParameterDriver> getParametersDrivers()

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

Returns:

drivers for this measurement parameters, including its modifiers parameters

getPropagatorsIndices

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.

Returns:

indices of the propagators related to this measurement

Since:

9.0

estimate

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.

Parameters:

iteration - iteration number

evaluation - evaluations number

states - orbital states at measurement date

Returns:

estimated measurement

Throws:

OrekitException - if value cannot be computed