org.orekit.propagation.events
Class ElevationDetector

java.lang.Object
  org.orekit.propagation.events.AbstractDetector
      org.orekit.propagation.events.ElevationDetector

All Implemented Interfaces:

java.io.Serializable, EventDetector

public class ElevationDetector
extends AbstractDetector

Finder for satellite raising/setting events.

This class finds elevation events (i.e. satellite raising and setting).

The default implementation behavior is to continue propagation at raising and to stop propagation at setting. This can be changed by overriding the eventOccurred method in a derived class.

Version:

$Revision: 3027 $ $Date: 2010-01-19 11:36:25 +0100 (mar. 19 janv. 2010) $

Author:

Luc Maisonobe

See Also:

Propagator.addEventDetector(EventDetector), Serialized Form

Field Summary

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

DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Fields inherited from interface org.orekit.propagation.events.EventDetector

CONTINUE, RESET_DERIVATIVES, RESET_STATE, STOP

Constructor Summary

ElevationDetector(double maxCheck, double threshold, double elevation, TopocentricFrame topo)
Build a new elevation detector.

ElevationDetector(double maxCheck, double elevation, TopocentricFrame topo)
Build a new elevation detector.

ElevationDetector(double elevation, TopocentricFrame topo)
Build a new elevation detector.

Method Summary

int	eventOccurred(SpacecraftState s, boolean increasing) Handle an elevation event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
double	getElevation() Get the threshold elevation value (°).
TopocentricFrame	getTopocentricFrame() Get the topocentric frame.

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

getMaxCheckInterval, getMaxIterationCount, getThreshold, resetState

Methods inherited from class java.lang.Object

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

Constructor Detail

ElevationDetector

public ElevationDetector(double elevation,
                         TopocentricFrame topo)

Build a new elevation detector.

This simple constructor takes default values for maximal checking interval (AbstractDetector.DEFAULT_MAXCHECK) and convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

Parameters:

elevation - threshold elevation value (°)

topo - topocentric frame in which elevation should be evaluated

ElevationDetector

public ElevationDetector(double maxCheck,
                         double elevation,
                         TopocentricFrame topo)

Build a new elevation detector.

This constructor takes default value for convergence threshold (AbstractDetector.DEFAULT_THRESHOLD).

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

Parameters:

maxCheck - maximal checking interval (s)

elevation - threshold elevation value (°)

topo - topocentric frame in which elevation should be evaluated

ElevationDetector

public ElevationDetector(double maxCheck,
                         double threshold,
                         double elevation,
                         TopocentricFrame topo)

Build a new elevation detector.

The maximal interval between elevation checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

Parameters:

maxCheck - maximal checking interval (s)

threshold - convergence threshold (s)

elevation - threshold elevation value (°)

topo - topocentric frame in which elevation should be evaluated

Method Detail

getElevation

public double getElevation()

Get the threshold elevation value (°).

Returns:

the threshold elevation value

getTopocentricFrame

public TopocentricFrame getTopocentricFrame()

Get the topocentric frame.

Returns:

the topocentric frame

eventOccurred

public int eventOccurred(SpacecraftState s,
                         boolean increasing)
                  throws OrekitException

Handle an elevation event and choose what to do next.

The default implementation behavior is to continue propagation at raising and to stop propagation at setting.

Specified by:

eventOccurred in interface EventDetector

Specified by:

eventOccurred in class AbstractDetector

Parameters:

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

increasing - if true, the value of the switching function increases when times increases around event.

Returns:

EventDetector.STOP or EventDetector.CONTINUE

Throws:

OrekitException - if some specific error occurs

g

public double g(SpacecraftState s)
         throws OrekitException

Compute the value of the switching function. This function measures the difference between the current elevation and the threshold elevation.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector

Parameters:

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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs