GroundReceiverMeasurement.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;

  19. import java.util.Collections;
  20. import java.util.HashMap;
  21. import java.util.Map;

  23. import org.hipparchus.analysis.differentiation.Gradient;
  24. import org.hipparchus.analysis.differentiation.GradientField;
  25. import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
  26. import org.hipparchus.geometry.euclidean.threed.Vector3D;
  27. import org.orekit.frames.FieldTransform;
  28. import org.orekit.frames.Frame;
  29. import org.orekit.frames.Transform;
  30. import org.orekit.propagation.SpacecraftState;
  31. import org.orekit.time.AbsoluteDate;
  32. import org.orekit.time.FieldAbsoluteDate;
  33. import org.orekit.utils.PVCoordinates;
  34. import org.orekit.utils.ParameterDriver;
  35. import org.orekit.utils.TimeSpanMap.Span;
  36. import org.orekit.utils.TimeStampedFieldPVCoordinates;
  37. import org.orekit.utils.TimeStampedPVCoordinates;

  39. /** Base class modeling a measurement where receiver is a ground station.
  40.  * @author Thierry Ceolin
  41.  * @author Luc Maisonobe
  42.  * @author Maxime Journot
  43.  * @since 12.0
  44.  * @param <T> type of the measurement
  45.  */
  46. public abstract class GroundReceiverMeasurement<T extends GroundReceiverMeasurement<T>> extends AbstractMeasurement<T> {

  48.     /** Ground station from which measurement is performed. */
  49.     private final GroundStation station;

  51.     /** Flag indicating whether it is a two-way measurement. */
  52.     private final boolean twoway;

  54.     /** Simple constructor.
  55.      * @param station ground station from which measurement is performed
  56.      * @param twoWay flag indicating whether it is a two-way measurement
  57.      * @param date date of the measurement
  58.      * @param observed observed value
  59.      * @param sigma theoretical standard deviation
  60.      * @param baseWeight base weight
  61.      * @param satellite satellite related to this measurement
  62.      */
  63.     public GroundReceiverMeasurement(final GroundStation station, final boolean twoWay, final AbsoluteDate date,
  64.                                      final double observed, final double sigma, final double baseWeight,
  65.                                      final ObservableSatellite satellite) {
  66.         super(date, observed, sigma, baseWeight, Collections.singletonList(satellite));
  67.         addParameterDriver(station.getClockOffsetDriver());
  68.         addParameterDriver(station.getClockDriftDriver());
  69.         addParameterDriver(station.getEastOffsetDriver());
  70.         addParameterDriver(station.getNorthOffsetDriver());
  71.         addParameterDriver(station.getZenithOffsetDriver());
  72.         addParameterDriver(station.getPrimeMeridianOffsetDriver());
  73.         addParameterDriver(station.getPrimeMeridianDriftDriver());
  74.         addParameterDriver(station.getPolarOffsetXDriver());
  75.         addParameterDriver(station.getPolarDriftXDriver());
  76.         addParameterDriver(station.getPolarOffsetYDriver());
  77.         addParameterDriver(station.getPolarDriftYDriver());
  78.         if (!twoWay) {
  79.             // for one way measurements, the satellite clock offset affects the measurement
  80.             addParameterDriver(satellite.getClockOffsetDriver());
  81.             addParameterDriver(satellite.getClockDriftDriver());
  82.         }
  83.         this.station = station;
  84.         this.twoway  = twoWay;
  85.     }

  87.     /** Simple constructor.
  88.      * @param station ground station from which measurement is performed
  89.      * @param twoWay flag indicating whether it is a two-way measurement
  90.      * @param date date of the measurement
  91.      * @param observed observed value
  92.      * @param sigma theoretical standard deviation
  93.      * @param baseWeight base weight
  94.      * @param satellite satellite related to this measurement
  95.      */
  96.     public GroundReceiverMeasurement(final GroundStation station, final boolean twoWay, final AbsoluteDate date,
  97.                                      final double[] observed, final double[] sigma, final double[] baseWeight,
  98.                                      final ObservableSatellite satellite) {
  99.         super(date, observed, sigma, baseWeight, Collections.singletonList(satellite));
  100.         addParameterDriver(station.getClockOffsetDriver());
  101.         addParameterDriver(station.getClockDriftDriver());
  102.         addParameterDriver(station.getEastOffsetDriver());
  103.         addParameterDriver(station.getNorthOffsetDriver());
  104.         addParameterDriver(station.getZenithOffsetDriver());
  105.         addParameterDriver(station.getPrimeMeridianOffsetDriver());
  106.         addParameterDriver(station.getPrimeMeridianDriftDriver());
  107.         addParameterDriver(station.getPolarOffsetXDriver());
  108.         addParameterDriver(station.getPolarDriftXDriver());
  109.         addParameterDriver(station.getPolarOffsetYDriver());
  110.         addParameterDriver(station.getPolarDriftYDriver());
  111.         if (!twoWay) {
  112.             // for one way measurements, the satellite clock offset affects the measurement
  113.             addParameterDriver(satellite.getClockOffsetDriver());
  114.             addParameterDriver(satellite.getClockDriftDriver());
  115.         }
  116.         this.station = station;
  117.         this.twoway  = twoWay;
  118.     }

  120.     /** Get the ground station from which measurement is performed.
  121.      * @return ground station from which measurement is performed
  122.      */
  123.     public GroundStation getStation() {
  124.         return station;
  125.     }

  127.     /** Check if the instance represents a two-way measurement.
  128.      * @return true if the instance represents a two-way measurement
  129.      */
  130.     public boolean isTwoWay() {
  131.         return twoway;
  132.     }

  134.     /** Compute common estimation parameters.
  135.      * @param state orbital state at measurement date
  136.      * @return common parameters
  137.      */
  138.     protected GroundReceiverCommonParametersWithoutDerivatives computeCommonParametersWithout(final SpacecraftState state) {

  140.         // Coordinates of the spacecraft
  141.         final TimeStampedPVCoordinates pva = state.getPVCoordinates();

  143.         // transform between station and inertial frame
  144.         final Transform offsetToInertialDownlink =
  145.                         getStation().getOffsetToInertial(state.getFrame(), getDate(), false);
  146.         final AbsoluteDate downlinkDate = offsetToInertialDownlink.getDate();

  148.         // Station position in inertial frame at end of the downlink leg
  149.         final TimeStampedPVCoordinates origin = new TimeStampedPVCoordinates(downlinkDate,
  150.                                                                              Vector3D.ZERO, Vector3D.ZERO, Vector3D.ZERO);
  151.         final TimeStampedPVCoordinates stationDownlink = offsetToInertialDownlink.transformPVCoordinates(origin);

  153.         // Compute propagation times
  154.         // (if state has already been set up to pre-compensate propagation delay,
  155.         //  we will have delta == tauD and transitState will be the same as state)

  157.         // Downlink delay
  158.         final double tauD = signalTimeOfFlight(pva, stationDownlink.getPosition(), downlinkDate);

  160.         // Transit state & Transit state (re)computed with gradients
  161.         final double          delta        = downlinkDate.durationFrom(state.getDate());
  162.         final double          deltaMTauD   = delta - tauD;
  163.         final SpacecraftState transitState = state.shiftedBy(deltaMTauD);

  165.         return new GroundReceiverCommonParametersWithoutDerivatives(state,
  166.                                                                     offsetToInertialDownlink,
  167.                                                                     stationDownlink,
  168.                                                                     tauD,
  169.                                                                     transitState,
  170.                                                                     transitState.getPVCoordinates());

  172.     }

  174.     /** Compute common estimation parameters.
  175.      * @param state orbital state at measurement date
  176.      * @return common parameters
  177.      */
  178.     protected GroundReceiverCommonParametersWithDerivatives computeCommonParametersWithDerivatives(final SpacecraftState state) {
  179.         int nbParams = 6;
  180.         final Map<String, Integer> indices = new HashMap<>();
  181.         for (ParameterDriver driver : getParametersDrivers()) {
  182.             if (driver.isSelected()) {
  183.                 for (Span<String> span = driver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
  184.                     indices.put(span.getData(), nbParams++);
  185.                 }
  186.             }
  187.         }
  188.         final FieldVector3D<Gradient> zero = FieldVector3D.getZero(GradientField.getField(nbParams));

  190.         // Coordinates of the spacecraft expressed as a gradient
  191.         final TimeStampedFieldPVCoordinates<Gradient> pva = getCoordinates(state, 0, nbParams);

  193.         // transform between station and inertial frame, expressed as a gradient
  194.         // The components of station's position in offset frame are the 3 last derivative parameters
  195.         final FieldTransform<Gradient> offsetToInertialDownlink =
  196.                         getStation().getOffsetToInertial(state.getFrame(), getDate(), nbParams, indices);
  197.         final FieldAbsoluteDate<Gradient> downlinkDate = offsetToInertialDownlink.getFieldDate();

  199.         // Station position in inertial frame at end of the downlink leg
  200.         final TimeStampedFieldPVCoordinates<Gradient> stationDownlink =
  201.                         offsetToInertialDownlink.transformPVCoordinates(new TimeStampedFieldPVCoordinates<>(downlinkDate,
  202.                                                                                                             zero, zero, zero));

  204.         // Compute propagation times
  205.         // (if state has already been set up to pre-compensate propagation delay,
  206.         //  we will have delta == tauD and transitState will be the same as state)

  208.         // Downlink delay
  209.         final Gradient tauD = signalTimeOfFlight(pva, stationDownlink.getPosition(), downlinkDate);

  211.         // Transit state & Transit state (re)computed with gradients
  212.         final Gradient        delta        = downlinkDate.durationFrom(state.getDate());
  213.         final Gradient        deltaMTauD   = tauD.negate().add(delta);
  214.         final SpacecraftState transitState = state.shiftedBy(deltaMTauD.getValue());
  215.         final TimeStampedFieldPVCoordinates<Gradient> transitPV = pva.shiftedBy(deltaMTauD);

  217.         return new GroundReceiverCommonParametersWithDerivatives(state,
  218.                                                                  indices,
  219.                                                                  offsetToInertialDownlink,
  220.                                                                  stationDownlink,
  221.                                                                  tauD,
  222.                                                                  transitState,
  223.                                                                  transitPV);

  225.     }

  227.     /**
  228.      * Get the station position for a given frame.
  229.      * @param frame inertial frame for station position
  230.      * @return the station position in the given inertial frame
  231.      * @since 12.0
  232.      */
  233.     public Vector3D getGroundStationPosition(final Frame frame) {
  234.         return station.getBaseFrame().getPosition(getDate(), frame);
  235.     }

  237.     /**
  238.      * Get the station coordinates for a given frame.
  239.      * @param frame inertial frame for station position
  240.      * @return the station coordinates in the given inertial frame
  241.      * @since 12.0
  242.      */
  243.     public PVCoordinates getGroundStationCoordinates(final Frame frame) {
  244.         return station.getBaseFrame().getPVCoordinates(getDate(), frame);
  245.     }

  247. }
Created with JaCoCo 0.8.11.202310140853