OneWayGNSSRangeRate.java

  1. /* Copyright 2022-2025 Thales Alenia Space
  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.estimation.measurements.gnss;

  19. import java.util.Arrays;

  21. import org.hipparchus.analysis.differentiation.Gradient;
  22. import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
  23. import org.hipparchus.geometry.euclidean.threed.Vector3D;
  24. import org.orekit.estimation.measurements.EstimatedMeasurement;
  25. import org.orekit.estimation.measurements.EstimatedMeasurementBase;
  26. import org.orekit.estimation.measurements.ObservableSatellite;
  27. import org.orekit.estimation.measurements.QuadraticClockModel;
  28. import org.orekit.propagation.SpacecraftState;
  29. import org.orekit.time.AbsoluteDate;
  30. import org.orekit.utils.Constants;
  31. import org.orekit.utils.FieldPVCoordinates;
  32. import org.orekit.utils.PVCoordinates;
  33. import org.orekit.utils.PVCoordinatesProvider;
  34. import org.orekit.utils.ParameterDriver;
  35. import org.orekit.utils.TimeSpanMap.Span;
  36. import org.orekit.utils.TimeStampedPVCoordinates;

  38. /** One-way GNSS range rate measurement.
  39.  * <p>
  40.  * This class can be used in precise orbit determination applications
  41.  * for modeling a range rate measurement between a GNSS satellite (emitter)
  42.  * and a LEO satellite (receiver).
  43.  * <p>
  44.  * The one-way GNSS range rate measurement assumes knowledge of the orbit and
  45.  * the clock offset of the emitting GNSS satellite. For instance, it is
  46.  * possible to use a SP3 file or a GNSS navigation message to recover
  47.  * the satellite's orbit and clock.
  48.  * <p>
  49.  * This class is very similar to {@link InterSatellitesOneWayRangeRate} measurement
  50.  * class. However, using the one-way GNSS range measurement, the orbit and clock
  51.  * of the emitting GNSS satellite are <b>NOT</b> estimated simultaneously with
  52.  * LEO satellite coordinates.
  53.  *
  54.  * @author Luc Maisonobe
  55.  * @since 12.1
  56.  */
  57. public class OneWayGNSSRangeRate extends AbstractOneWayGNSSMeasurement<OneWayGNSSRangeRate> {

  59.     /** Type of the measurement. */
  60.     public static final String MEASUREMENT_TYPE = "OneWayGNSSRangeRate";

  62.     /** Simple constructor.
  63.      * @param remote provider for GNSS satellite which simply emits the signal
  64.      * @param dtRemote clock offset of the GNSS satellite, in seconds
  65.      * @param date date of the measurement
  66.      * @param rangeRate observed value
  67.      * @param sigma theoretical standard deviation
  68.      * @param baseWeight base weight
  69.      * @param local satellite which receives the signal and perform the measurement
  70.      */
  71.     public OneWayGNSSRangeRate(final PVCoordinatesProvider remote,
  72.                                final double dtRemote,
  73.                                final AbsoluteDate date,
  74.                                final double rangeRate, final double sigma,
  75.                                final double baseWeight, final ObservableSatellite local) {
  76.         this(remote, new QuadraticClockModel(date, dtRemote, 0.0, 0.0), date, rangeRate, sigma, baseWeight, local);
  77.     }

  79.     /** Simple constructor.
  80.      * @param remote provider for GNSS satellite which simply emits the signal
  81.      * @param remoteClock clock offset of the GNSS satellite
  82.      * @param date date of the measurement
  83.      * @param rangeRate observed value
  84.      * @param sigma theoretical standard deviation
  85.      * @param baseWeight base weight
  86.      * @param local satellite which receives the signal and perform the measurement
  87.      * @since 12.1
  88.      */
  89.     public OneWayGNSSRangeRate(final PVCoordinatesProvider remote,
  90.                                final QuadraticClockModel remoteClock,
  91.                                final AbsoluteDate date,
  92.                                final double rangeRate, final double sigma,
  93.                                final double baseWeight, final ObservableSatellite local) {
  94.         // Call super constructor
  95.         super(remote, remoteClock, date, rangeRate, sigma, baseWeight, local);
  96.     }

  98.     /** {@inheritDoc} */
  99.     @Override
  100.     protected EstimatedMeasurementBase<OneWayGNSSRangeRate> theoreticalEvaluationWithoutDerivatives(final int iteration,
  101.                                                                                                     final int evaluation,
  102.                                                                                                     final SpacecraftState[] states) {


  105.         final OnBoardCommonParametersWithoutDerivatives common = computeCommonParametersWithout(states, false);

  107.         // Estimated measurement
  108.         final EstimatedMeasurementBase<OneWayGNSSRangeRate> estimatedRangeRate =
  109.                         new EstimatedMeasurementBase<>(this, iteration, evaluation,
  110.                                                        new SpacecraftState[] {
  111.                                                            common.getState()
  112.                                                        }, new TimeStampedPVCoordinates[] {
  113.                                                            common.getRemotePV(),
  114.                                                            common.getTransitPV()
  115.                                                        });

  117.         // Range rate value
  118.         final PVCoordinates delta = new PVCoordinates(common.getRemotePV(), common.getTransitPV());
  119.         final double rangeRate = Vector3D.dotProduct(delta.getVelocity(), delta.getPosition().normalize()) +
  120.                                  Constants.SPEED_OF_LIGHT * (common.getLocalRate() - common.getRemoteRate());

  122.         // Set value of the estimated measurement
  123.         estimatedRangeRate.setEstimatedValue(rangeRate);

  125.         // Return the estimated measurement
  126.         return estimatedRangeRate;

  128.     }

  130.     /** {@inheritDoc} */
  131.     @Override
  132.     protected EstimatedMeasurement<OneWayGNSSRangeRate> theoreticalEvaluation(final int iteration,
  133.                                                                               final int evaluation,
  134.                                                                               final SpacecraftState[] states) {

  136.         final OnBoardCommonParametersWithDerivatives common = computeCommonParametersWith(states, false);

  138.         // Estimated measurement
  139.         final EstimatedMeasurement<OneWayGNSSRangeRate> estimatedRangeRate =
  140.                         new EstimatedMeasurement<>(this, iteration, evaluation,
  141.                                                    new SpacecraftState[] {
  142.                                                        common.getState()
  143.                                                    }, new TimeStampedPVCoordinates[] {
  144.                                                        common.getRemotePV().toTimeStampedPVCoordinates(),
  145.                                                        common.getTransitPV().toTimeStampedPVCoordinates()
  146.                                                    });

  148.         // Range rate value
  149.         final FieldPVCoordinates<Gradient> delta = new FieldPVCoordinates<>(common.getRemotePV(), common.getTransitPV());
  150.         final Gradient rangeRate = FieldVector3D.dotProduct(delta.getVelocity(), delta.getPosition().normalize()).
  151.                                    add(common.getLocalRate().subtract(common.getRemoteRate()).multiply(Constants.SPEED_OF_LIGHT));
  152.         final double[] rangeRateDerivatives = rangeRate.getGradient();

  154.         // Set value and state first order derivatives of the estimated measurement
  155.         estimatedRangeRate.setEstimatedValue(rangeRate.getValue());
  156.         estimatedRangeRate.setStateDerivatives(0, Arrays.copyOfRange(rangeRateDerivatives, 0,  6));

  158.         // Set first order derivatives with respect to parameters
  159.         for (final ParameterDriver measurementDriver : getParametersDrivers()) {
  160.             for (Span<String> span = measurementDriver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {

  162.                 final Integer index = common.getIndices().get(span.getData());
  163.                 if (index != null) {
  164.                     estimatedRangeRate.setParameterDerivatives(measurementDriver, span.getStart(), rangeRateDerivatives[index]);
  165.                 }
  166.             }
  167.         }

  169.         // Return the estimated measurement
  170.         return estimatedRangeRate;

  172.     }

  174. }
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