org.orekit.propagation.events

Class InterSatDirectViewDetector

java.lang.Object

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

org.orekit.propagation.events.InterSatDirectViewDetector

All Implemented Interfaces:

EventDetector

public class InterSatDirectViewDetector
extends AbstractDetector<InterSatDirectViewDetector>

Detector for inter-satellites direct view (i.e. no masking by central body limb).

As this detector needs two satellites, it embeds one coordinates provider for the slave satellite and is registered as an event detector in the propagator of the master satellite. The slave satellite provider will therefore be driven by this detector (and hence by the propagator in which this detector is registered).

In order to avoid infinite recursion, care must be taken to have the slave satellite provider being completely independent from anything else. In particular, if the provider is a propagator, it should not be run together in a propagators parallelizer with the propagator this detector is registered in. It is fine however to configure two separate propagators PsA and PsB with similar settings for the slave satellite and one propagator Pm for the master satellite and then use Psa in this detector registered within Pm while Pm and Psb are run in the context of a propagators parallelizer.

For efficiency reason during the event search loop, it is recommended to have the slave provider be an analytical propagator or an ephemeris. A numerical propagator as a slave propagator works but is expected to be computationally costly.

The g function of this detector is positive when satellites can see each other directly and negative when the central body limb is in between and blocks the direct view.

This detector only checks masking by central body limb, it does not take into account satellites antenna patterns. If these patterns must be considered, then this detector can be and combined with the logical not of field of view detectors.

Since:

9.3

Author:

Luc Maisonobe

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
InterSatDirectViewDetector(OneAxisEllipsoid body, PVCoordinatesProvider slave) simple constructor.

Method Summary

Modifier and Type	Method and Description
protected InterSatDirectViewDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super InterSatDirectViewDetector> newHandler) Build a new instance.
double	g(SpacecraftState state) Compute the value of the switching function.
OneAxisEllipsoid	getCentralBody() Get the central body.
PVCoordinatesProvider	getSlave() Get the provider for the slave satellite.

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

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, init, isForward, resetState, withHandler, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

InterSatDirectViewDetector

public InterSatDirectViewDetector(OneAxisEllipsoid body,
                                  PVCoordinatesProvider slave)

simple constructor.

Parameters:

body - central body

slave - provider for the slave satellite

Method Detail

getCentralBody

public OneAxisEllipsoid getCentralBody()

Get the central body.

Returns:

central body

getSlave

public PVCoordinatesProvider getSlave()

Get the provider for the slave satellite.

Returns:

provider for the slave satellite

create

protected InterSatDirectViewDetector create(double newMaxCheck,
                                            double newThreshold,
                                            int newMaxIter,
                                            EventHandler<? super InterSatDirectViewDetector> newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<InterSatDirectViewDetector>

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

g

public double g(SpacecraftState state)

Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

The g function of this detector is positive when satellites can see each other directly and negative when the central body limb is in between and blocks the direct view.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<InterSatDirectViewDetector>

Parameters:

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

Returns:

value of the switching function