Package org.orekit.propagation.events

Class MagneticFieldDetector

java.lang.Object

org.orekit.propagation.events.AbstractDetector<MagneticFieldDetector>

org.orekit.propagation.events.MagneticFieldDetector

All Implemented Interfaces:

EventDetector

public class MagneticFieldDetector
extends AbstractDetector<MagneticFieldDetector>

Detector for Earth magnetic field strength.

The detector is based on the field intensity calculated at the satellite's latitude and longitude, either at sea level or at satellite altitude, depending on the value chosen for the atSeaLevel indicator.
It can detect flyovers of the South-Atlantic anomaly with a classically accepted limit value of 32,000 nT at sea level.

Author:

Romaric Her

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Modifier	Constructor	Description
	MagneticFieldDetector(double maxCheck, double threshold, double limit, GeoMagneticFieldFactory.FieldModel model, OneAxisEllipsoid body, boolean atSeaLevel)	Build a detector.
	MagneticFieldDetector(double maxCheck, double threshold, double limit, GeoMagneticFieldFactory.FieldModel model, OneAxisEllipsoid body, boolean atSeaLevel, DataContext dataContext)	Build a detector.
	MagneticFieldDetector(double limit, GeoMagneticFieldFactory.FieldModel model, OneAxisEllipsoid body)	Build a new detector.
	MagneticFieldDetector(double limit, GeoMagneticFieldFactory.FieldModel model, OneAxisEllipsoid body, boolean atSeaLevel)	Build a new detector.
protected	MagneticFieldDetector(AdaptableInterval maxCheck, double threshold, int maxIter, EventHandler handler, double limit, GeoMagneticFieldFactory.FieldModel model, OneAxisEllipsoid body, boolean atSeaLevel, DataContext dataContext)	Protected constructor with full parameters.

Method Summary

Modifier and Type	Method	Description
protected MagneticFieldDetector	create(AdaptableInterval newMaxCheck, double newThreshold, int newMaxIter, EventHandler newHandler)	Build a new instance.
double	g(SpacecraftState s)	Compute the value of the detection function.
void	init(SpacecraftState s0, AbsoluteDate t)	Initialize event handler at the start of a propagation.

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

getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, isForward, withHandler, withMaxCheck, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

MagneticFieldDetector

@DefaultDataContext
public MagneticFieldDetector(double limit,
                             GeoMagneticFieldFactory.FieldModel model,
                             OneAxisEllipsoid body)

Build a new detector.

This constructor uses:

• the default data context
• the default value for maximal checking interval
• the default value for convergence threshold
• the atSeaLevel switch set to false

Parameters:

limit - threshold value for magnetic field detection, in Teslas

model - magnetic field model

body - Earth body shape

See Also:

MagneticFieldDetector(double, double, double, GeoMagneticFieldFactory.FieldModel, OneAxisEllipsoid, boolean, DataContext)

MagneticFieldDetector

@DefaultDataContext
public MagneticFieldDetector(double limit,
                             GeoMagneticFieldFactory.FieldModel model,
                             OneAxisEllipsoid body,
                             boolean atSeaLevel)

Build a new detector.

This constructor uses:

• the default data context
• the default value for maximal checking interval
• the default value for convergence threshold

Parameters:

limit - threshold value for magnetic field detection, in Teslas

model - magnetic field model

body - Earth body shape

atSeaLevel - switch for calculating field intensity at sea level (true) or satellite altitude (false)

See Also:

MagneticFieldDetector(double, double, double, GeoMagneticFieldFactory.FieldModel, OneAxisEllipsoid, boolean, DataContext)

MagneticFieldDetector

@DefaultDataContext
public MagneticFieldDetector(double maxCheck,
                             double threshold,
                             double limit,
                             GeoMagneticFieldFactory.FieldModel model,
                             OneAxisEllipsoid body,
                             boolean atSeaLevel)

Build a detector.

This method uses the default data context.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

limit - threshold value for magnetic field detection, in Teslas

model - magnetic field model

body - Earth body shape

atSeaLevel - switch for calculating field intensity at sea level (true) or satellite altitude (false)

See Also:

MagneticFieldDetector(double, double, double, GeoMagneticFieldFactory.FieldModel, OneAxisEllipsoid, boolean, DataContext)

MagneticFieldDetector

public MagneticFieldDetector(double maxCheck,
                             double threshold,
                             double limit,
                             GeoMagneticFieldFactory.FieldModel model,
                             OneAxisEllipsoid body,
                             boolean atSeaLevel,
                             DataContext dataContext)

Build a detector.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

limit - threshold value for magnetic field detection, in Teslas

model - magnetic field model

body - Earth body shape

atSeaLevel - switch for calculating field intensity at sea level (true) or satellite altitude (false)

dataContext - used to look up the magnetic field model.

Since:

10.1

MagneticFieldDetector

protected MagneticFieldDetector(AdaptableInterval maxCheck,
                                double threshold,
                                int maxIter,
                                EventHandler handler,
                                double limit,
                                GeoMagneticFieldFactory.FieldModel model,
                                OneAxisEllipsoid body,
                                boolean atSeaLevel,
                                DataContext dataContext)

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:

maxCheck - maximal checking interval

threshold - convergence threshold (s)

maxIter - maximum number of iterations in the event time search

handler - event handler to call at event occurrences

limit - threshold value for magnetic field detection, in Teslas

model - magnetic field model

body - Earth body shape

atSeaLevel - switch for calculating field intensity at sea level (true) or satellite altitude (false)

dataContext - used to look up the magnetic field model.

Method Detail

create

protected MagneticFieldDetector create(AdaptableInterval newMaxCheck,
                                       double newThreshold,
                                       int newMaxIter,
                                       EventHandler newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<MagneticFieldDetector>

Parameters:

newMaxCheck - maximum checking interval (s)

newThreshold - convergence threshold (s)

newMaxIter - maximum number of iterations in the event time search

newHandler - event handler to call at event occurrences

Returns:

a new instance of the appropriate sub-type

init

public void init(SpacecraftState s0,
                 AbsoluteDate t)

Initialize event handler at the start of a propagation.

This method is called once at the start of the propagation. It may be used by the event handler to initialize some internal data if needed.

The default implementation does nothing

This implementation sets the direction of propagation and initializes the event handler. If a subclass overrides this method it should call super.init(s0, t).

Specified by:

init in interface EventDetector

Overrides:

init in class AbstractDetector<MagneticFieldDetector>

Parameters:

s0 - initial state

t - target time for the integration

g

public double g(SpacecraftState s)

Compute the value of the detection function.

The returned value is the difference between the field intensity at spacecraft location, taking atSeaLevel switch into account, and the fixed threshold value.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<MagneticFieldDetector>

Parameters:

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

Returns:

difference between the field intensity at spacecraft location and the fixed threshold value