Package org.orekit.estimation.measurements

Class FDOA

java.lang.Object

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

org.orekit.estimation.measurements.SignalBasedMeasurement<FDOA>

org.orekit.estimation.measurements.DualReceiverMeasurement<FDOA>

org.orekit.estimation.measurements.FDOA

All Implemented Interfaces:

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

public class FDOA
extends DualReceiverMeasurement<FDOA>

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

FDOA measures the difference in signal arrival frequency between the emitter and receivers, corresponding to a difference in range-rate 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 frequency of the signal received at the prime station at the date of the measurement minus the frequency of the signal received at the second station: fdoa = f1 - f2

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

Since:

12.0

Author:

Mark Rutten

Field Summary

Fields

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

Constructor Summary

Constructors

Constructor	Description
FDOA(Observer primeObserver, Observer secondObserver, double centreFrequency, AbsoluteDate date, double fdoa, double sigma, double baseWeight, ObservableSatellite satellite)	Constructor with default signal travel time model.
FDOA(Observer primeObserver, Observer secondObserver, double centreFrequency, AbsoluteDate date, double fdoa, MeasurementQuality measurementQuality, SignalTravelTimeModel signalTravelTimeModel, ObservableSatellite satellite)	Constructor.

Method Summary

Modifier and Type	Method	Description
double	getCentreFrequency()	Get centre frequency of carrier wave.
protected EstimatedMeasurement<FDOA>	theoreticalEvaluation(int iteration, int evaluation, SpacecraftState[] states)	Estimate the theoretical value.
protected EstimatedMeasurementBase<FDOA>	theoreticalEvaluationWithoutDerivatives(int iteration, int evaluation, SpacecraftState[] states, boolean fillParticipants)	Estimate the theoretical value without derivatives.

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

computeDelays, fillEstimation, getPrimeObserver, getPrimeStation, getSecondObserver, getSecondStation

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

getSignalTravelTimeModel, isTwoWay

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

addModifier, addParameterDriver, addParametersDrivers, estimate, estimateWithoutDerivatives, getCoordinates, getDate, getMeasurementQuality, getModifiers, getObservedValue, getParameterIndices, getParametersDrivers, getSatellites, isEnabled, setEnabled, setObservedValue, theoreticalEvaluationWithoutDerivatives

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, getBaseWeight, getDimension, getMeasurementType, getTheoreticalStandardDeviation

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 Details

MEASUREMENT_TYPE

public static final String MEASUREMENT_TYPE

Type of the measurement.

See Also:

• Constant Field Values

Constructor Details

FDOA

public FDOA(Observer primeObserver,
 Observer secondObserver,
 double centreFrequency,
 AbsoluteDate date,
 double fdoa,
 double sigma,
 double baseWeight,
 ObservableSatellite satellite)

Constructor with default signal travel time model.

Parameters:

primeObserver - observer that gives the date of the measurement

secondObserver - observer that gives the measurement

centreFrequency - satellite emitter frequency (Hz)

date - date of the measurement

fdoa - observed value (Hz)

sigma - theoretical standard deviation

baseWeight - base weight

satellite - satellite related to this measurement

FDOA

public FDOA(Observer primeObserver,
 Observer secondObserver,
 double centreFrequency,
 AbsoluteDate date,
 double fdoa,
 MeasurementQuality measurementQuality,
 SignalTravelTimeModel signalTravelTimeModel,
 ObservableSatellite satellite)

Constructor.

Parameters:

primeObserver - observer that gives the date of the measurement

secondObserver - observer that gives the measurement

centreFrequency - satellite emitter frequency (Hz)

date - date of the measurement

fdoa - observed value (Hz)

measurementQuality - measurement quality data as used in orbit determination

signalTravelTimeModel - signal travel time model

satellite - satellite related to this measurement

Since:

14.0

Method Details

getCentreFrequency

public double getCentreFrequency()

Get centre frequency of carrier wave.

Returns:

frequency value (Hz)

theoreticalEvaluationWithoutDerivatives

protected EstimatedMeasurementBase<FDOA> theoreticalEvaluationWithoutDerivatives(int iteration,
 int evaluation,
 SpacecraftState[] states,
 boolean fillParticipants)

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<FDOA>

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

fillParticipants - flag to compute and store participants dynamical states at measurement date and along signal path if applicable

Returns:

theoretical value

See Also:

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

theoreticalEvaluation

protected EstimatedMeasurement<FDOA> 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<FDOA>

Parameters:

iteration - iteration number

evaluation - evaluation number

states - orbital states at measurement date

Returns:

theoretical value

See Also:

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