Package org.orekit.propagation.events

Class FieldAngularSeparationDetector<T extends CalculusFieldElement<T>>

java.lang.Object

org.orekit.propagation.events.FieldAbstractDetector<FieldAngularSeparationDetector<T>,T>

org.orekit.propagation.events.FieldAngularSeparationDetector<T>

Type Parameters:

T - type of the field elements

All Implemented Interfaces:

FieldEventDetector<T>

public class FieldAngularSeparationDetector<T extends CalculusFieldElement<T>>
extends FieldAbstractDetector<FieldAngularSeparationDetector<T>,T>

Detects when spacecraft comes close to a moving beacon, as seen from a moving observer.

The main use case for this detector is when the observer is in fact a ground station, modeled as a TopocentricFrame and when the beacon is the Sun, for computing interferences for the telemetry link. Another similar case is when the beacon is another spacecraft, for interferences computation.

The default handler behavior is to stop propagation when spacecraft enters the proximity zone. This can be changed by calling #withHandler(EventHandler) after construction.

Since:

13.1

Author:

Luc Maisonobe, Romain Serra

See Also:

• Propagator.addEventDetector(EventDetector)
• AngularSeparationDetector

Field Summary

Fields inherited from class org.orekit.propagation.events.FieldAbstractDetector

DEFAULT_MAX_CHECK, DEFAULT_MAX_ITER, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FieldAngularSeparationDetector(FieldEventDetectionSettings<T> detectionSettings, FieldEventHandler<T> handler, ExtendedPositionProvider beacon, ExtendedPositionProvider observer, T proximityAngle)	Protected constructor with full parameters.
	FieldAngularSeparationDetector(ExtendedPositionProvider beacon, ExtendedPositionProvider observer, T proximityAngle)	Build a new angular separation detector.

Method Summary

Modifier and Type	Method	Description
protected FieldAngularSeparationDetector<T>	create(FieldEventDetectionSettings<T> detectionSettings, FieldEventHandler<T> newHandler)	Build a new instance.
T	g(FieldSpacecraftState<T> s)	Compute the value of the switching function.
ExtendedPositionProvider	getBeacon()	Get the beacon at the center of the proximity zone.
ExtendedPositionProvider	getObserver()	Get the observer for the spacecraft.
T	getProximityAngle()	Get the proximity angle (rad).
AngularSeparationDetector	toEventDetector(EventHandler eventHandler)	Build non-Field instance.

Methods inherited from class org.orekit.propagation.events.FieldAbstractDetector

checkIfForward, getDetectionSettings, getEventFunction, getHandler, init, isForward, withDetectionSettings, withHandler, withMaxCheck, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.propagation.events.FieldEventDetector

finish, getMaxCheckInterval, getMaxIterationCount, getThreshold, reset

Constructor Details

FieldAngularSeparationDetector

public FieldAngularSeparationDetector(ExtendedPositionProvider beacon,
 ExtendedPositionProvider observer,
 T proximityAngle)

Build a new angular separation detector.

Parameters:

beacon - beacon at the center of the proximity zone

observer - observer for the spacecraft, that may also see the beacon at the same time if they are too close to each other

proximityAngle - proximity angle as seen from observer, at which events are triggered (rad)

FieldAngularSeparationDetector

protected FieldAngularSeparationDetector(FieldEventDetectionSettings<T> detectionSettings,
 FieldEventHandler<T> handler,
 ExtendedPositionProvider beacon,
 ExtendedPositionProvider observer,
 T proximityAngle)

Protected constructor with full parameters.

This constructor is not public as users are expected to use the builder API with the various withXxx() methods to set up the instance in a readable manner without using a huge amount of parameters.

Parameters:

detectionSettings - detection settings

handler - event handler to call at event occurrences

beacon - beacon at the center of the proximity zone

observer - observer for the spacecraft, that may also see the beacon at the same time if they are too close to each other

proximityAngle - proximity angle as seen from observer, at which events are triggered (rad)

Since:

13.0

Method Details

create

protected FieldAngularSeparationDetector<T> create(FieldEventDetectionSettings<T> detectionSettings,
 FieldEventHandler<T> newHandler)

Build a new instance.

Specified by:

create in class FieldAbstractDetector<FieldAngularSeparationDetector<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Parameters:

detectionSettings - detection settings

newHandler - event handler to call at event occurrences

Returns:

a new instance of the appropriate sub-type

getBeacon

public ExtendedPositionProvider getBeacon()

Get the beacon at the center of the proximity zone.

Returns:

beacon at the center of the proximity zone

getObserver

public ExtendedPositionProvider getObserver()

Get the observer for the spacecraft.

Returns:

observer for the spacecraft

getProximityAngle

public T getProximityAngle()

Get the proximity angle (rad).

Returns:

the proximity angle

g

public T g(FieldSpacecraftState<T> s)

Compute the value of the switching function.

This function measures the angular separation between beacon and spacecraft as seen from the observer minus the proximity angle. It therefore triggers decreasing events when the spacecraft enters the proximity zone and increasing events when it leaves the proximity zone.

No shadowing effect is taken into account, so this method is computed and may trigger events even when the spacecraft is below horizon for an observer which is a ground station. If such effects must be taken into account the detector must be associated with a predicate filter where the predicate function is based on elevation.

Parameters:

s - the current state information: date, kinematics, attitude

Returns:

value of the switching function

toEventDetector

public AngularSeparationDetector toEventDetector(EventHandler eventHandler)

Build non-Field instance.

Overrides:

toEventDetector in class FieldAbstractDetector<FieldAngularSeparationDetector<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Parameters:

eventHandler - event handler

Returns:

event detector