OneWayGNSSPhaseBuilder.java

  1. /* Copyright 2002-2024 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.estimation.measurements.generation;

  19. import java.util.Map;
  20. import java.util.function.Function;
  21. import java.util.function.ToDoubleFunction;

  23. import org.hipparchus.random.CorrelatedRandomVectorGenerator;
  24. import org.orekit.estimation.measurements.EstimationModifier;
  25. import org.orekit.estimation.measurements.ObservableSatellite;
  26. import org.orekit.estimation.measurements.QuadraticClockModel;
  27. import org.orekit.estimation.measurements.gnss.AmbiguityCache;
  28. import org.orekit.estimation.measurements.gnss.OneWayGNSSPhase;
  29. import org.orekit.propagation.SpacecraftState;
  30. import org.orekit.propagation.sampling.OrekitStepInterpolator;
  31. import org.orekit.time.AbsoluteDate;
  32. import org.orekit.utils.ParameterDriver;


  35. /** Builder for {@link OneWayGNSSPhase} measurements.
  36.  * @author Luc Maisonobe
  37.  * @since 12.0
  38.  */
  39. public class OneWayGNSSPhaseBuilder extends AbstractMeasurementBuilder<OneWayGNSSPhase> {

  41.     /** Cache for ambiguities.
  42.      * @since 12.1
  43.      */
  44.     private final AmbiguityCache cache;

  46.     /** Wavelength of the phase observed value [m]. */
  47.     private final double wavelength;

  49.     /** Satellite which receives the signal and performs the measurement. */
  50.     private final ObservableSatellite local;

  52.     /** Satellite which simply emits the signal. */
  53.     private final ObservableSatellite remote;

  55.     /** Clock model of the remote satellite that provides clock offset. */
  56.     private final QuadraticClockModel remoteClockModel;

  58.     /** Temporary builder for clock models.
  59.      * @deprecated this is a temporary field, it will be removed in Orekit 13.0
  60.      */
  61.     @Deprecated
  62.     private Function<AbsoluteDate, QuadraticClockModel> clockBuilder;

  64.     /** Simple constructor.
  65.      * @param noiseSource noise source, may be null for generating perfect measurements
  66.      * @param local satellite which receives the signal and performs the measurement
  67.      * @param remote satellite which simply emits the signal
  68.      * @param remoteClockModel clock model of the remote satellite that provides clock offset
  69.      * @param wavelength phase observed value wavelength (m)
  70.      * @param sigma theoretical standard deviation
  71.      * @param baseWeight base weight
  72.      * @deprecated as of 12.1, replaced by {@link #OneWayGNSSPhaseBuilder(CorrelatedRandomVectorGenerator,
  73.      * ObservableSatellite, ObservableSatellite, QuadraticClockModel,
  74.      * double, double, double, AmbiguityCache)}
  75.      */
  76.     @Deprecated
  77.     public OneWayGNSSPhaseBuilder(final CorrelatedRandomVectorGenerator noiseSource,
  78.                                   final ObservableSatellite local, final ObservableSatellite remote,
  79.                                   final ToDoubleFunction<AbsoluteDate> remoteClockModel,
  80.                                   final double wavelength, final double sigma, final double baseWeight) {
  81.         this(noiseSource, local, remote, null, wavelength, sigma, baseWeight,
  82.              AmbiguityCache.DEFAULT_CACHE);
  83.         this.clockBuilder = date -> {
  84.             final double cM = remoteClockModel.applyAsDouble(date.shiftedBy(-1));
  85.             final double c0 = remoteClockModel.applyAsDouble(date);
  86.             final double cP = remoteClockModel.applyAsDouble(date.shiftedBy(1));
  87.             return new QuadraticClockModel(date, c0, 0.5 * (cP - cM), 0.5 * (cP + cM) - c0);
  88.         };
  89.     }

  91.     /** Simple constructor.
  92.      * @param noiseSource noise source, may be null for generating perfect measurements
  93.      * @param local satellite which receives the signal and performs the measurement
  94.      * @param remote satellite which simply emits the signal
  95.      * @param remoteClockModel clock model of the remote satellite that provides clock offset
  96.      * @param wavelength phase observed value wavelength (m)
  97.      * @param sigma theoretical standard deviation
  98.      * @param baseWeight base weight
  99.      * @param cache from which ambiguity drive should come
  100.      * @since 12.1
  101.      */
  102.     public OneWayGNSSPhaseBuilder(final CorrelatedRandomVectorGenerator noiseSource,
  103.                                   final ObservableSatellite local, final ObservableSatellite remote,
  104.                                   final QuadraticClockModel remoteClockModel,
  105.                                   final double wavelength, final double sigma, final double baseWeight,
  106.                                   final AmbiguityCache cache) {
  107.         super(noiseSource, sigma, baseWeight, local, remote);
  108.         this.wavelength       = wavelength;
  109.         this.local            = local;
  110.         this.remote           = remote;
  111.         this.remoteClockModel = remoteClockModel;
  112.         this.cache            = cache;
  113.     }

  115.     /** {@inheritDoc} */
  116.     @Override
  117.     public OneWayGNSSPhase build(final AbsoluteDate date,
  118.                                  final Map<ObservableSatellite, OrekitStepInterpolator> interpolators) {

  120.         final double sigma               = getTheoreticalStandardDeviation()[0];
  121.         final double baseWeight          = getBaseWeight()[0];
  122.         final SpacecraftState[] relevant = new SpacecraftState[] {
  123.             interpolators.get(local).getInterpolatedState(date),
  124.             interpolators.get(remote).getInterpolatedState(date)
  125.         };

  127.         // temporary hack to build QuadraticClockModel from ToDoubleFunction<AbsoluteDate>
  128.         // for compatibility purposes
  129.         final QuadraticClockModel clockModel = remoteClockModel != null ?
  130.                                                remoteClockModel :
  131.                                                clockBuilder.apply(date);

  133.         // create a dummy measurement
  134.         final OneWayGNSSPhase dummy = new OneWayGNSSPhase(interpolators.get(remote),
  135.                                                           remote.getName(),
  136.                                                           clockModel, date,
  137.                                                           Double.NaN, wavelength,
  138.                                                           sigma, baseWeight, local,
  139.                                                           cache);
  140.         for (final EstimationModifier<OneWayGNSSPhase> modifier : getModifiers()) {
  141.             dummy.addModifier(modifier);
  142.         }

  144.         // set a reference date for parameters missing one
  145.         for (final ParameterDriver driver : dummy.getParametersDrivers()) {
  146.             if (driver.getReferenceDate() == null) {
  147.                 final AbsoluteDate start = getStart();
  148.                 final AbsoluteDate end   = getEnd();
  149.                 driver.setReferenceDate(start.durationFrom(end) <= 0 ? start : end);
  150.             }
  151.         }

  153.         // estimate the perfect value of the measurement
  154.         double phase = dummy.estimateWithoutDerivatives(relevant).getEstimatedValue()[0];

  156.         // add the noise
  157.         final double[] noise = getNoise();
  158.         if (noise != null) {
  159.             phase += noise[0];
  160.         }

  162.         // generate measurement
  163.         final OneWayGNSSPhase measurement = new OneWayGNSSPhase(interpolators.get(remote),
  164.                                                                 remote.getName(),
  165.                                                                 clockModel, date,
  166.                                                                 phase, wavelength, sigma, baseWeight, local,
  167.                                                                 cache);
  168.         for (final EstimationModifier<OneWayGNSSPhase> modifier : getModifiers()) {
  169.             measurement.addModifier(modifier);
  170.         }
  171.         return measurement;

  173.     }

  175. }
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