FieldGnssOrbitalElements.java

  1. /* Copyright 2022-2025 Luc Maisonobe
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.propagation.analytical.gnss.data;

  19. import org.hipparchus.CalculusFieldElement;
  20. import org.hipparchus.Field;
  21. import org.hipparchus.util.FastMath;
  22. import org.orekit.gnss.SatelliteSystem;
  23. import org.orekit.time.FieldAbsoluteDate;
  24. import org.orekit.time.FieldTimeStamped;
  25. import org.orekit.time.GNSSDate;
  26. import org.orekit.time.TimeScales;

  28. import java.util.function.Function;

  30. /** This class provides the minimal set of orbital elements needed by the {@link
  31.  * org.orekit.propagation.analytical.gnss.FieldGnssPropagator}.
  32.  * @param <T> type of the field elements
  33.  * @param <O> type of the orbital elements (non-field version)
  34.  * @since 13.0
  35.  * @author Luc Maisonobe
  36. */
  37. public abstract class FieldGnssOrbitalElements<T extends CalculusFieldElement<T>, O extends GNSSOrbitalElements<O>>
  38.     extends GNSSOrbitalElementsDriversProvider
  39.     implements FieldTimeStamped<T> {

  41.     /** Earth's universal gravitational parameter. */
  42.     private final T mu;

  44.     /** Reference epoch. */
  45.     private FieldAbsoluteDate<T> date;

  47.     /** Semi-Major Axis (m). */
  48.     private T sma;

  50.     /** Eccentricity. */
  51.     private T ecc;

  53.     /** Inclination angle at reference time (rad). */
  54.     private T i0;

  56.     /** Argument of perigee (rad). */
  57.     private T aop;

  59.     /** Longitude of ascending node of orbit plane at weekly epoch (rad). */
  60.     private T om0;

  62.     /** Mean anomaly at reference time (rad). */
  63.     private T anom;

  65.     /** Simple constructor.
  66.      * @param mu              Earth's universal gravitational parameter
  67.      * @param angularVelocity mean angular velocity of the Earth for the GNSS model
  68.      * @param weeksInCycle    number of weeks in the GNSS cycle
  69.      * @param timeScales      known time scales
  70.      * @param system          satellite system to consider for interpreting week number
  71.      *                        (may be different from real system, for example in Rinex nav, weeks
  72.      *                        are always according to GPS)
  73.      */
  74.     protected FieldGnssOrbitalElements(final T mu, final double angularVelocity, final int weeksInCycle,
  75.                                        final TimeScales timeScales, final SatelliteSystem system) {

  77.         super(angularVelocity, weeksInCycle, timeScales, system);

  79.         // immutable field
  80.         this.mu   = mu;

  82.         // Keplerian orbital elements
  83.         this.sma  = mu.newInstance(Double.NaN);
  84.         this.ecc  = mu.newInstance(Double.NaN);
  85.         this.i0   = mu.newInstance(Double.NaN);
  86.         this.aop  = mu.newInstance(Double.NaN);
  87.         this.om0  = mu.newInstance(Double.NaN);
  88.         this.anom = mu.newInstance(Double.NaN);

  90.     }

  92.     /** Constructor from non-field instance.
  93.      * @param field    field to which elements belong
  94.      * @param original regular non-field instance
  95.      */
  96.     protected FieldGnssOrbitalElements(final Field<T> field, final O original) {

  98.         super(original.getAngularVelocity(), original.getWeeksInCycle(),
  99.               original.getTimeScales(), original.getSystem());
  100.         mu = field.getZero().newInstance(original.getMu());

  102.         // non-Keplerian parameters
  103.         setPRN(original.getPRN());
  104.         setWeek(original.getWeek());
  105.         setTime(original.getTime());
  106.         setIDot(original.getIDot());
  107.         setOmegaDot(original.getOmegaDot());
  108.         setCuc(original.getCuc());
  109.         setCus(original.getCus());
  110.         setCrc(original.getCrc());
  111.         setCrs(original.getCrs());
  112.         setCic(original.getCic());
  113.         setCis(original.getCis());

  115.         // Keplerian orbital elements
  116.         setGnssDate(new GNSSDate(original.getWeek(), original.getTime(), original.getSystem(), original.getTimeScales()));
  117.         setSma(field.getZero().newInstance(original.getSma()));
  118.         setE(field.getZero().newInstance(original.getE()));
  119.         setI0(field.getZero().newInstance(original.getI0()));
  120.         setPa(field.getZero().newInstance(original.getPa()));
  121.         setOmega0(field.getZero().newInstance(original.getOmega0()));
  122.         setM0(field.getZero().newInstance(original.getM0()));

  124.         // copy selection settings
  125.         copySelectionSettings(original);

  127.     }

  129.     /** Constructor from different field instance.
  130.      * @param <V> type of the old field elements
  131.      * @param original regular non-field instance
  132.      * @param converter for field elements
  133.      */
  134.     protected <V extends CalculusFieldElement<V>> FieldGnssOrbitalElements(final Function<V, T> converter,
  135.                                                                            final FieldGnssOrbitalElements<V, O> original) {
  136.         super(original.getAngularVelocity(), original.getWeeksInCycle(),
  137.               original.getTimeScales(), original.getSystem());
  138.         mu = converter.apply(original.getMu());

  140.         // non-Keplerian parameters
  141.         setPRN(original.getPRN());
  142.         setWeek(original.getWeek());
  143.         setTime(original.getTime());
  144.         setIDot(original.getIDot());
  145.         setOmegaDot(original.getOmegaDot());
  146.         setCuc(original.getCuc());
  147.         setCus(original.getCus());
  148.         setCrc(original.getCrc());
  149.         setCrs(original.getCrs());
  150.         setCic(original.getCic());
  151.         setCis(original.getCis());

  153.         // Keplerian orbital elements
  154.         setGnssDate(new GNSSDate(original.getWeek(), original.getTime(), original.getSystem(), original.getTimeScales()));
  155.         setSma(converter.apply(original.getSma()));
  156.         setE(converter.apply(original.getE()));
  157.         setI0(converter.apply(original.getI0()));
  158.         setPa(converter.apply(original.getPa()));
  159.         setOmega0(converter.apply(original.getOmega0()));
  160.         setM0(converter.apply(original.getM0()));

  162.         // copy selection settings
  163.         copySelectionSettings(original);

  165.     }

  167.     /** Create a non-field version of the instance.
  168.      * @return non-field version of the instance
  169.      */
  170.     public abstract O toNonField();

  172.     /**
  173.      * Create another field version of the instance.
  174.      *
  175.      * @param <U>       type of the new field elements
  176.      * @param <G>       type of the orbital elements (field version)
  177.      * @param converter for field elements
  178.      * @return field version of the instance
  179.      */
  180.     public abstract <U extends CalculusFieldElement<U>, G extends FieldGnssOrbitalElements<U, O>>
  181.         G changeField(Function<T, U> converter);

  183.     /** {@inheritDoc} */
  184.     protected void setGnssDate(final GNSSDate gnssDate) {
  185.         this.date = new FieldAbsoluteDate<>(mu.getField(), gnssDate.getDate());
  186.     }

  188.     /** Get date.
  189.      * @return date
  190.      */
  191.     public FieldAbsoluteDate<T> getDate() {
  192.         return date;
  193.     }

  195.     /** Get the Earth's universal gravitational parameter.
  196.      * @return the Earth's universal gravitational parameter
  197.      */
  198.     public T getMu() {
  199.         return mu;
  200.     }

  202.     /** Get semi-major axis.
  203.      * @return semi-major axis (m)
  204.      */
  205.     public T getSma() {
  206.         return sma;
  207.     }

  209.     /** Set semi-major axis.
  210.      * @param sma demi-major axis (m)
  211.      */
  212.     public void setSma(final T sma) {
  213.         this.sma = sma;
  214.     }

  216.     /** Getter for the change rate in semi-major axis.
  217.      * <p>
  218.      * This value is non-zero only in civilian navigation messages
  219.      * </p>
  220.      * @return the change rate in semi-major axis
  221.      * @since 13.0
  222.      */
  223.     public T getADot() {
  224.         return mu.getField().getZero();
  225.     }

  227.     /** Get the computed mean motion n₀.
  228.      * @return the computed mean motion n₀ (rad/s)
  229.      * @since 13.0
  230.      */
  231.     public T getMeanMotion0() {
  232.         final T invA = FastMath.abs(getSma()).reciprocal();
  233.         return FastMath.sqrt(getMu().multiply(invA)).multiply(invA);
  234.     }

  236.     /** Getter for the delta of satellite mean motion.
  237.      * <p>
  238.      * This value is non-zero only in navigation messages
  239.      * </p>
  240.      * @return delta of satellite mean motion
  241.      * @since 13.0
  242.      */
  243.     public T getDeltaN0() {
  244.         return mu.getField().getZero();
  245.     }

  247.     /** Getter for change rate in Δn₀.
  248.      * <p>
  249.      * This value is non-zero only in civilian navigation messages
  250.      * </p>
  251.      * @return change rate in Δn₀
  252.      * @since 13.0
  253.      */
  254.     public T getDeltaN0Dot() {
  255.         return mu.getField().getZero();
  256.     }

  258.     /** Get eccentricity.
  259.      * @return eccentricity
  260.      */
  261.     public T getE() {
  262.         return ecc;
  263.     }

  265.     /** Set eccentricity.
  266.      * @param e eccentricity
  267.      */
  268.     public void setE(final T e) {
  269.         this.ecc = e;
  270.     }

  272.     /** Get the inclination angle at reference time.
  273.      * @return inclination angle at reference time (rad)
  274.      */
  275.     public T getI0() {
  276.         return i0;
  277.     }

  279.     /** Set inclination angle at reference time.
  280.      * @param i0 inclination angle at reference time (rad)
  281.      */
  282.     public void setI0(final T i0) {
  283.         this.i0 = i0;
  284.     }

  286.     /** Get longitude of ascending node of orbit plane at weekly epoch.
  287.      * @return longitude of ascending node of orbit plane at weekly epoch (rad)
  288.      */
  289.     public T getOmega0() {
  290.         return om0;
  291.     }

  293.     /** Set longitude of ascending node of orbit plane at weekly epoch.
  294.      * @param omega0 longitude of ascending node of orbit plane at weekly epoch (rad)
  295.      */
  296.     public void setOmega0(final T omega0) {
  297.         this.om0 = omega0;
  298.     }

  300.     /** Get argument of perigee.
  301.      * @return argument of perigee (rad)
  302.      */
  303.     public T getPa() {
  304.         return aop;
  305.     }

  307.     /** Set argument of perigee.
  308.      * @param pa argument of perigee (rad)
  309.      */
  310.     public void setPa(final T pa) {
  311.         this.aop = pa;
  312.     }

  314.     /** Get mean anomaly at reference time.
  315.      * @return mean anomaly at reference time (rad)
  316.      */
  317.     public T getM0() {
  318.         return anom;
  319.     }

  321.     /** Set mean anomaly at reference time.
  322.      * @param m0 mean anomaly at reference time (rad)
  323.      */
  324.     public void setM0(final T m0) {
  325.         this.anom = m0;
  326.     }

  328. }
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