GPSPropagator.java
/* Copyright 2002-2020 CS GROUP
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* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
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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 GPS orbit from {@link GPSOrbitalElements}.
*
* @see <a href="http://www.gps.gov/technical/icwg/IS-GPS-200H.pdf">GPS Interface Specification</a>
* @author Pascal Parraud
* @since 8.0
*/
public class GPSPropagator extends AbstractGNSSPropagator {
// Constants
/** WGS 84 value of the earth's rotation rate in rad/s. */
private static final double GPS_AV = 7.2921151467e-5;
/** Duration of the GPS cycle in seconds. */
private static final double GPS_CYCLE_DURATION = GPSOrbitalElements.GPS_WEEK_IN_SECONDS *
GPSOrbitalElements.GPS_WEEK_NB;
// Fields
/** The GPS orbital elements used. */
private final GPSOrbitalElements gpsOrbit;
/**
* This nested class aims at building a GPSPropagator.
* <p>It implements the classical builder pattern.</p>
*
*/
public static class Builder {
// Required parameter
/** The GPS orbital elements. */
private final GPSOrbitalElements 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 GPS orbital elements is the only requested parameter to build a GPSPropagator.</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 GPSOrbitalElements gpsOrbElt, final Frames frames)}</p>
*
* @param gpsOrbElt the GPS orbital elements to be used by the GPSpropagator.
* @see #attitudeProvider(AttitudeProvider provider)
* @see #mass(double mass)
* @see #eci(Frame inertial)
* @see #ecef(Frame bodyFixed)
*/
@DefaultDataContext
public Builder(final GPSOrbitalElements gpsOrbElt) {
this(gpsOrbElt, DataContext.getDefault().getFrames());
}
/** Initializes the builder.
* <p>The GPS orbital elements is the only requested parameter to build a GPSPropagator.</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 Frames#getEME2000() EME2000 frame}.<br>
* The ECEF frame is set by default to the
* {@link Frames#getITRF(IERSConventions, boolean)} CIO/2010-based ITRF simple EOP}.
* </p>
*
* @param gpsOrbElt the GPS orbital elements to be used by the GPSpropagator.
* @param frames set of frames to use.
* @see #attitudeProvider(AttitudeProvider provider)
* @see #mass(double mass)
* @see #eci(Frame inertial)
* @see #ecef(Frame bodyFixed)
* @since 10.1
*/
public Builder(final GPSOrbitalElements gpsOrbElt, final Frames frames) {
this.orbit = gpsOrbElt;
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 assimilated to the WGS84 ECEF.
*
* @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 GPSPropagator
*/
public GPSPropagator build() {
return new GPSPropagator(this);
}
}
/**
* Private constructor.
*
* @param builder the builder
*/
private GPSPropagator(final Builder builder) {
super(builder.orbit, builder.attitudeProvider,
builder.eci, builder.ecef, builder.mass,
GPS_AV, GPS_CYCLE_DURATION, GPSOrbitalElements.GPS_MU);
// Stores the GPS orbital elements
this.gpsOrbit = builder.orbit;
}
/**
* Gets the underlying GPS orbital elements.
*
* @return the underlying GPS orbital elements
*/
public GPSOrbitalElements getGPSOrbitalElements() {
return gpsOrbit;
}
}