BeidouPropagator.java
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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package org.orekit.propagation.analytical.gnss;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.attitudes.AttitudeProvider;
import org.orekit.data.DataContext;
import org.orekit.frames.Frame;
import org.orekit.frames.Frames;
import org.orekit.propagation.Propagator;
import org.orekit.utils.IERSConventions;
/**
* This class aims at propagating a Beidou orbit from {@link BeidouOrbitalElements}.
*
* @see <a href="http://www2.unb.ca/gge/Resources/beidou_icd_english_ver2.0.pdf">Beidou Interface Control Document</a>
*
* @author Bryan Cazabonne
* @since 10.0
*
*/
public class BeidouPropagator extends AbstractGNSSPropagator {
// Constants
/** Value of the earth's rotation rate in rad/s. */
private static final double BEIDOU_AV = 7.2921150e-5;
/** Duration of the Beidou cycle in seconds. */
private static final double BEIDOU_CYCLE_DURATION = BeidouOrbitalElements.BEIDOU_WEEK_IN_SECONDS *
BeidouOrbitalElements.BEIDOU_WEEK_NB;
// Fields
/** The Beidou orbital elements used. */
private final BeidouOrbitalElements bdsOrbit;
/**
* This nested class aims at building a BeidouPropagator.
* <p>It implements the classical builder pattern.</p>
*
*/
public static class Builder {
// Required parameter
/** The Beidou orbital elements. */
private final BeidouOrbitalElements orbit;
// Optional parameters
/** The attitude provider. */
private AttitudeProvider attitudeProvider;
/** The mass. */
private double mass = DEFAULT_MASS;
/** The ECI frame. */
private Frame eci = null;
/** The ECEF frame. */
private Frame ecef = null;
/** Initializes the builder.
* <p>The Beidou orbital elements is the only requested parameter to build a BeidouPropagator.</p>
* <p>The attitude provider is set by default to the
* {@link org.orekit.propagation.Propagator#DEFAULT_LAW DEFAULT_LAW} in the
* default data context.<br>
* The mass is set by default to the
* {@link org.orekit.propagation.Propagator#DEFAULT_MASS DEFAULT_MASS}.<br>
* The ECI frame is set by default to the
* {@link org.orekit.frames.Predefined#EME2000 EME2000 frame} in the default data
* context.<br>
* The ECEF frame is set by default to the
* {@link org.orekit.frames.Predefined#ITRF_CIO_CONV_2010_SIMPLE_EOP
* CIO/2010-based ITRF simple EOP} in the default data context.
* </p>
*
* <p>This constructor uses the {@link DataContext#getDefault() default data context}.
* Another data context can be set using
* {@code Builder(final BeidouOrbitalElements gpsOrbElt, final Frames frames)}</p>
*
* @param bdsOrbElt the Beidou orbital elements to be used by the Beidou propagator.
* @see #attitudeProvider(AttitudeProvider provider)
* @see #mass(double mass)
* @see #eci(Frame inertial)
* @see #ecef(Frame bodyFixed)
*/
@DefaultDataContext
public Builder(final BeidouOrbitalElements bdsOrbElt) {
this(bdsOrbElt, DataContext.getDefault().getFrames());
}
/** Initializes the builder.
* <p>The Beidou orbital elements is the only requested parameter to build a BeidouPropagator.</p>
* <p>The attitude provider is set by default to the
* {@link org.orekit.propagation.Propagator#getDefaultLaw(Frames)
* DEFAULT_LAW}.<br>
* The mass is set by default to the
* {@link org.orekit.propagation.Propagator#DEFAULT_MASS DEFAULT_MASS}.<br>
* The ECI frame is set by default to the
* {@link org.orekit.frames.Predefined#EME2000 EME2000 frame}.<br>
* The ECEF frame is set by default to the
* {@link org.orekit.frames.Predefined#ITRF_CIO_CONV_2010_SIMPLE_EOP
* CIO/2010-based ITRF simple EOP}.
* </p>
*
* @param bdsOrbElt the Beidou orbital elements to be used by the Beidou propagator.
* @param frames set of frames to use building the propagator.
* @see #attitudeProvider(AttitudeProvider provider)
* @see #mass(double mass)
* @see #eci(Frame inertial)
* @see #ecef(Frame bodyFixed)
* @since 10.1
*/
public Builder(final BeidouOrbitalElements bdsOrbElt, final Frames frames) {
this.orbit = bdsOrbElt;
this.eci = frames.getEME2000();
this.ecef = frames.getITRF(IERSConventions.IERS_2010, true);
attitudeProvider = Propagator.getDefaultLaw(frames);
}
/** Sets the attitude provider.
*
* @param userProvider the attitude provider
* @return the updated builder
*/
public Builder attitudeProvider(final AttitudeProvider userProvider) {
this.attitudeProvider = userProvider;
return this;
}
/** Sets the mass.
*
* @param userMass the mass (in kg)
* @return the updated builder
*/
public Builder mass(final double userMass) {
this.mass = userMass;
return this;
}
/** Sets the Earth Centered Inertial frame used for propagation.
*
* @param inertial the ECI frame
* @return the updated builder
*/
public Builder eci(final Frame inertial) {
this.eci = inertial;
return this;
}
/** Sets the Earth Centered Earth Fixed frame.
*
* @param bodyFixed the ECEF frame
* @return the updated builder
*/
public Builder ecef(final Frame bodyFixed) {
this.ecef = bodyFixed;
return this;
}
/** Finalizes the build.
*
* @return the built BeidouPropagator
*/
public BeidouPropagator build() {
return new BeidouPropagator(this);
}
}
/**
* Private constructor.
*
* @param builder the builder
*/
private BeidouPropagator(final Builder builder) {
super(builder.orbit, builder.attitudeProvider,
builder.eci, builder.ecef, builder.mass,
BEIDOU_AV, BEIDOU_CYCLE_DURATION, BeidouOrbitalElements.BEIDOU_MU);
// Stores the Beidou orbital elements
this.bdsOrbit = builder.orbit;
}
/**
* Get the underlying Beidou orbital elements.
*
* @return the underlying Beidou orbital elements
*/
public BeidouOrbitalElements getBeidouOrbitalElements() {
return bdsOrbit;
}
}