FieldGnssOrbitalElements.java
/* Copyright 2022-2025 Luc Maisonobe
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.propagation.analytical.gnss.data;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.util.FastMath;
import org.orekit.gnss.SatelliteSystem;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.time.FieldTimeStamped;
import org.orekit.time.GNSSDate;
import org.orekit.time.TimeScales;
import java.util.function.Function;
/** This class provides the minimal set of orbital elements needed by the {@link
* org.orekit.propagation.analytical.gnss.FieldGnssPropagator}.
* @param <T> type of the field elements
* @param <O> type of the orbital elements (non-field version)
* @since 13.0
* @author Luc Maisonobe
*/
public abstract class FieldGnssOrbitalElements<T extends CalculusFieldElement<T>, O extends GNSSOrbitalElements<O>>
extends GNSSOrbitalElementsDriversProvider
implements FieldTimeStamped<T> {
/** Earth's universal gravitational parameter. */
private final T mu;
/** Reference epoch. */
private FieldAbsoluteDate<T> date;
/** Semi-Major Axis (m). */
private T sma;
/** Eccentricity. */
private T ecc;
/** Inclination angle at reference time (rad). */
private T i0;
/** Argument of perigee (rad). */
private T aop;
/** Longitude of ascending node of orbit plane at weekly epoch (rad). */
private T om0;
/** Mean anomaly at reference time (rad). */
private T anom;
/** Simple constructor.
* @param mu Earth's universal gravitational parameter
* @param angularVelocity mean angular velocity of the Earth for the GNSS model
* @param weeksInCycle number of weeks in the GNSS cycle
* @param timeScales known time scales
* @param system satellite system to consider for interpreting week number
* (may be different from real system, for example in Rinex nav, weeks
* are always according to GPS)
*/
protected FieldGnssOrbitalElements(final T mu, final double angularVelocity, final int weeksInCycle,
final TimeScales timeScales, final SatelliteSystem system) {
super(angularVelocity, weeksInCycle, timeScales, system);
// immutable field
this.mu = mu;
// Keplerian orbital elements
this.sma = mu.newInstance(Double.NaN);
this.ecc = mu.newInstance(Double.NaN);
this.i0 = mu.newInstance(Double.NaN);
this.aop = mu.newInstance(Double.NaN);
this.om0 = mu.newInstance(Double.NaN);
this.anom = mu.newInstance(Double.NaN);
}
/** Constructor from non-field instance.
* @param field field to which elements belong
* @param original regular non-field instance
*/
protected FieldGnssOrbitalElements(final Field<T> field, final O original) {
super(original.getAngularVelocity(), original.getWeeksInCycle(),
original.getTimeScales(), original.getSystem());
mu = field.getZero().newInstance(original.getMu());
// non-Keplerian parameters
copyNonKeplerian(original);
// Keplerian orbital elements
setGnssDate(new GNSSDate(original.getWeek(), original.getTime(), original.getSystem(), original.getTimeScales()));
setSma(field.getZero().newInstance(original.getSma()));
setE(field.getZero().newInstance(original.getE()));
setI0(field.getZero().newInstance(original.getI0()));
setPa(field.getZero().newInstance(original.getPa()));
setOmega0(field.getZero().newInstance(original.getOmega0()));
setM0(field.getZero().newInstance(original.getM0()));
// copy selection settings
copySelectionSettings(original);
}
/** Constructor from different field instance.
* @param <V> type of the old field elements
* @param original regular non-field instance
* @param converter for field elements
*/
protected <V extends CalculusFieldElement<V>> FieldGnssOrbitalElements(final Function<V, T> converter,
final FieldGnssOrbitalElements<V, O> original) {
super(original.getAngularVelocity(), original.getWeeksInCycle(),
original.getTimeScales(), original.getSystem());
mu = converter.apply(original.getMu());
// non-Keplerian parameters
copyNonKeplerian(original);
// Keplerian orbital elements
setGnssDate(new GNSSDate(original.getWeek(), original.getTime(), original.getSystem(), original.getTimeScales()));
setSma(converter.apply(original.getSma()));
setE(converter.apply(original.getE()));
setI0(converter.apply(original.getI0()));
setPa(converter.apply(original.getPa()));
setOmega0(converter.apply(original.getOmega0()));
setM0(converter.apply(original.getM0()));
// copy selection settings
copySelectionSettings(original);
}
/** Create a non-field version of the instance.
* @return non-field version of the instance
*/
public abstract O toNonField();
/**
* Create another field version of the instance.
*
* @param <U> type of the new field elements
* @param <G> type of the orbital elements (field version)
* @param converter for field elements
* @return field version of the instance
*/
public abstract <U extends CalculusFieldElement<U>, G extends FieldGnssOrbitalElements<U, O>>
G changeField(Function<T, U> converter);
/** {@inheritDoc} */
protected void setGnssDate(final GNSSDate gnssDate) {
this.date = new FieldAbsoluteDate<>(mu.getField(), gnssDate.getDate());
}
/** Get date.
* @return date
*/
public FieldAbsoluteDate<T> getDate() {
return date;
}
/** Get the Earth's universal gravitational parameter.
* @return the Earth's universal gravitational parameter
*/
public T getMu() {
return mu;
}
/** Get semi-major axis.
* @return semi-major axis (m)
*/
public T getSma() {
return sma;
}
/** Set semi-major axis.
* @param sma demi-major axis (m)
*/
public void setSma(final T sma) {
this.sma = sma;
}
/** Get the computed mean motion n₀.
* @return the computed mean motion n₀ (rad/s)
* @since 13.0
*/
public T getMeanMotion0() {
final T invA = FastMath.abs(getSma()).reciprocal();
return FastMath.sqrt(getMu().multiply(invA)).multiply(invA);
}
/** Get eccentricity.
* @return eccentricity
*/
public T getE() {
return ecc;
}
/** Set eccentricity.
* @param e eccentricity
*/
public void setE(final T e) {
this.ecc = e;
}
/** Get the inclination angle at reference time.
* @return inclination angle at reference time (rad)
*/
public T getI0() {
return i0;
}
/** Set inclination angle at reference time.
* @param i0 inclination angle at reference time (rad)
*/
public void setI0(final T i0) {
this.i0 = i0;
}
/** Get longitude of ascending node of orbit plane at weekly epoch.
* @return longitude of ascending node of orbit plane at weekly epoch (rad)
*/
public T getOmega0() {
return om0;
}
/** Set longitude of ascending node of orbit plane at weekly epoch.
* @param omega0 longitude of ascending node of orbit plane at weekly epoch (rad)
*/
public void setOmega0(final T omega0) {
this.om0 = omega0;
}
/** Get argument of perigee.
* @return argument of perigee (rad)
*/
public T getPa() {
return aop;
}
/** Set argument of perigee.
* @param pa argument of perigee (rad)
*/
public void setPa(final T pa) {
this.aop = pa;
}
/** Get mean anomaly at reference time.
* @return mean anomaly at reference time (rad)
*/
public T getM0() {
return anom;
}
/** Set mean anomaly at reference time.
* @param m0 mean anomaly at reference time (rad)
*/
public void setM0(final T m0) {
this.anom = m0;
}
}