Package org.orekit.estimation.measurements

Class TDOA

java.lang.Object

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

org.orekit.estimation.measurements.GroundReceiverMeasurement<TDOA>

org.orekit.estimation.measurements.TDOA

All Implemented Interfaces:

Comparable<ComparableMeasurement>, ComparableMeasurement, ObservedMeasurement<TDOA>, TimeStamped, ParameterDriversProvider

public class TDOA
extends GroundReceiverMeasurement<TDOA>

Class modeling a Time Difference of Arrival measurement with a satellite as emitter and two ground stations as receivers.

TDOA measures the difference in signal arrival time between the emitter and receivers, corresponding to a difference in ranges from the two receivers to the emitter.

The date of the measurement corresponds to the reception of the signal by the prime station. The measurement corresponds to the date of the measurement minus the date of reception of the signal by the second station: tdoa = tr1 - tr2

The motion of the stations and the satellite during the signal flight time are taken into account.

Since:

11.2

Author:

Pascal Parraud

Field Summary

Fields

Modifier and Type	Field	Description
static String	MEASUREMENT_TYPE	Type of the measurement.

Constructor Summary

Constructors

Constructor	Description
TDOA(GroundStation primeStation, GroundStation secondStation, AbsoluteDate date, double tdoa, double sigma, double baseWeight, ObservableSatellite satellite)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
static <T extends CalculusFieldElement<T>> T	forwardSignalTimeOfFlight(TimeStampedFieldPVCoordinates<T> adjustableEmitterPV, FieldVector3D<T> receiverPosition, FieldAbsoluteDate<T> signalArrivalDate)	Compute propagation delay on a link leg (typically downlink or uplink).This differs from signalTimeOfFlight through advancing rather than delaying the emitter.
static double	forwardSignalTimeOfFlight(TimeStampedPVCoordinates adjustableEmitterPV, Vector3D receiverPosition, AbsoluteDate signalArrivalDate)	Compute propagation delay on a link leg (typically downlink or uplink).
GroundStation	getPrimeStation()	Get the prime ground station, the one that gives the date of the measurement.
GroundStation	getSecondStation()	Get the second ground station, the one that gives the measurement.
protected EstimatedMeasurement<TDOA>	theoreticalEvaluation(int iteration, int evaluation, SpacecraftState[] states)	Estimate the theoretical value.
protected EstimatedMeasurementBase<TDOA>	theoreticalEvaluationWithoutDerivatives(int iteration, int evaluation, SpacecraftState[] states)	Estimate the theoretical value without derivatives.

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

computeCommonParametersWithDerivatives, computeCommonParametersWithout, getGroundStationCoordinates, getGroundStationPosition, getStation, isTwoWay

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

addModifier, addParameterDriver, estimate, estimateWithoutDerivatives, getBaseWeight, getCoordinates, getDate, getDimension, getModifiers, getObservedValue, getParametersDrivers, getSatellites, getTheoreticalStandardDeviation, isEnabled, setEnabled, setObservedValue, signalTimeOfFlightAdjustableEmitter, signalTimeOfFlightAdjustableEmitter, signalTimeOfFlightAdjustableEmitter, signalTimeOfFlightAdjustableEmitter, signalTimeOfFlightAdjustableReceiver, signalTimeOfFlightAdjustableReceiver, signalTimeOfFlightAdjustableReceiver, signalTimeOfFlightAdjustableReceiver

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

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

estimateWithoutDerivatives, getMeasurementType

Methods inherited from interface org.orekit.utils.ParameterDriversProvider

getNbParametersDriversValue, getParameterDriver, getParameters, getParameters, getParameters, getParameters, getParametersAllValues, getParametersAllValues, isSupported

Methods inherited from interface org.orekit.time.TimeStamped

durationFrom

Field Detail

MEASUREMENT_TYPE

public static final String MEASUREMENT_TYPE

Type of the measurement.

See Also:

Constant Field Values

Constructor Detail

TDOA

public TDOA(GroundStation primeStation,
            GroundStation secondStation,
            AbsoluteDate date,
            double tdoa,
            double sigma,
            double baseWeight,
            ObservableSatellite satellite)

Simple constructor.

Parameters:

primeStation - ground station that gives the date of the measurement

secondStation - ground station that gives the measurement

date - date of the measurement

tdoa - observed value (s)

sigma - theoretical standard deviation

baseWeight - base weight

satellite - satellite related to this measurement

Method Detail

getPrimeStation

public GroundStation getPrimeStation()

Get the prime ground station, the one that gives the date of the measurement.

Returns:

prime ground station

getSecondStation

public GroundStation getSecondStation()

Get the second ground station, the one that gives the measurement.

Returns:

second ground station

theoreticalEvaluationWithoutDerivatives

protected EstimatedMeasurementBase<TDOA> theoreticalEvaluationWithoutDerivatives(int iteration,
                                                                                 int evaluation,
                                                                                 SpacecraftState[] states)

Estimate the theoretical value without derivatives. The default implementation uses the computation with derivatives and ought to be overwritten for performance.

The theoretical value does not have any modifiers applied.

Overrides:

theoreticalEvaluationWithoutDerivatives in class AbstractMeasurement<TDOA>

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

Returns:

theoretical value

See Also:

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

theoreticalEvaluation

protected EstimatedMeasurement<TDOA> 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<TDOA>

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

Returns:

theoretical value

See Also:

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

forwardSignalTimeOfFlight

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

Compute propagation delay on a link leg (typically downlink or uplink). This differs from signalTimeOfFlight through advancing rather than delaying the emitter.

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

forwardSignalTimeOfFlight

public static <T extends CalculusFieldElement<T>> T forwardSignalTimeOfFlight(TimeStampedFieldPVCoordinates<T> adjustableEmitterPV,
                                                                              FieldVector3D<T> receiverPosition,
                                                                              FieldAbsoluteDate<T> signalArrivalDate)

Compute propagation delay on a link leg (typically downlink or uplink).This differs from signalTimeOfFlight through advancing rather than delaying the emitter.

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