RangeRateTroposphericDelayModifier.java

  1. /* Copyright 2002-2024 CS GROUP
  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.modifiers;

  18. import org.hipparchus.CalculusFieldElement;
  19. import org.orekit.attitudes.FrameAlignedProvider;
  20. import org.orekit.estimation.measurements.EstimatedMeasurement;
  21. import org.orekit.estimation.measurements.EstimatedMeasurementBase;
  22. import org.orekit.estimation.measurements.EstimationModifier;
  23. import org.orekit.estimation.measurements.GroundStation;
  24. import org.orekit.estimation.measurements.RangeRate;
  25. import org.orekit.models.earth.troposphere.DiscreteTroposphericModel;
  26. import org.orekit.propagation.FieldSpacecraftState;
  27. import org.orekit.propagation.SpacecraftState;

  28. /** Class modifying theoretical range-rate measurements with tropospheric delay.
  29.  * The effect of tropospheric correction on the range-rate is directly computed
  30.  * through the computation of the tropospheric delay difference with respect to
  31.  * time.
  32.  *
  33.  * In general, for GNSS, VLBI, ... there is hardly any frequency dependence in the delay.
  34.  * For SLR techniques however, the frequency dependence is sensitive.
  35.  *
  36.  * @author Joris Olympio
  37.  * @since 8.0
  38.  */
  39. public class RangeRateTroposphericDelayModifier extends BaseRangeRateTroposphericDelayModifier implements EstimationModifier<RangeRate> {

  40.     /** Two-way measurement factor. */
  41.     private final double fTwoWay;

  42.     /** Constructor.
  43.      *
  44.      * @param model  Tropospheric delay model appropriate for the current range-rate measurement method.
  45.      * @param tw     Flag indicating whether the measurement is two-way.
  46.      */
  47.     public RangeRateTroposphericDelayModifier(final DiscreteTroposphericModel model, final boolean tw) {
  48.         super(model);
  49.         if (tw) {
  50.             fTwoWay = 2.;
  51.         } else {
  52.             fTwoWay = 1.;
  53.         }
  54.     }

  55.     /** Compute the measurement error due to Troposphere.
  56.      * @param station station
  57.      * @param state spacecraft state
  58.      * @return the measurement error due to Troposphere
  59.      */
  60.     @Override
  61.     public double rangeRateErrorTroposphericModel(final GroundStation station,
  62.                                                   final SpacecraftState state) {
  63.         return fTwoWay * super.rangeRateErrorTroposphericModel(station, state);
  64.     }


  65.     /** Compute the measurement error due to Troposphere.
  66.      * @param <T> type of the element
  67.      * @param station station
  68.      * @param state spacecraft state
  69.      * @param parameters tropospheric model parameters
  70.      * @return the measurement error due to Troposphere
  71.      */
  72.     @Override
  73.     public <T extends CalculusFieldElement<T>> T rangeRateErrorTroposphericModel(final GroundStation station,
  74.                                                                                  final FieldSpacecraftState<T> state,
  75.                                                                                  final T[] parameters) {
  76.         return super.rangeRateErrorTroposphericModel(station, state, parameters).multiply(fTwoWay);
  77.     }

  78.     /** {@inheritDoc} */
  79.     @Override
  80.     public void modifyWithoutDerivatives(final EstimatedMeasurementBase<RangeRate> estimated) {

  81.         final RangeRate       measurement = estimated.getObservedMeasurement();
  82.         final GroundStation   station     = measurement.getStation();

  83.         RangeRateModifierUtil.modifyWithoutDerivatives(estimated,  station, this::rangeRateErrorTroposphericModel);


  84.     }

  85.     /** {@inheritDoc} */
  86.     @Override
  87.     public void modify(final EstimatedMeasurement<RangeRate> estimated) {

  88.         final RangeRate       measurement = estimated.getObservedMeasurement();
  89.         final GroundStation   station     = measurement.getStation();
  90.         final SpacecraftState state       = estimated.getStates()[0];

  91.         RangeRateModifierUtil.modify(estimated, getTropoModel(),
  92.                                      new ModifierGradientConverter(state, 6, new FrameAlignedProvider(state.getFrame())),
  93.                                      station,
  94.                                      this::rangeRateErrorTroposphericModel,
  95.                                      this::rangeRateErrorTroposphericModel);


  96.     }

  97. }