OnBoardAntennaTurnAroundRangeModifier.java
- /* Copyright 2002-2019 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.estimation.measurements.modifiers;
- import java.util.Collections;
- import java.util.List;
- import org.hipparchus.geometry.euclidean.threed.Vector3D;
- import org.orekit.estimation.measurements.EstimatedMeasurement;
- import org.orekit.estimation.measurements.EstimationModifier;
- import org.orekit.estimation.measurements.TurnAroundRange;
- import org.orekit.frames.Transform;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.utils.ParameterDriver;
- import org.orekit.utils.TimeStampedPVCoordinates;
- /** On-board antenna offset effect on turn around range measurements.
- * @author Luc Maisonobe
- * @since 9.0
- */
- public class OnBoardAntennaTurnAroundRangeModifier implements EstimationModifier<TurnAroundRange> {
- /** Position of the Antenna Phase Center in satellite frame. */
- private final Vector3D antennaPhaseCenter;
- /** Simple constructor.
- * @param antennaPhaseCenter position of the Antenna Phase Center in satellite frame
- */
- public OnBoardAntennaTurnAroundRangeModifier(final Vector3D antennaPhaseCenter) {
- this.antennaPhaseCenter = antennaPhaseCenter;
- }
- /** {@inheritDoc} */
- @Override
- public List<ParameterDriver> getParametersDrivers() {
- return Collections.emptyList();
- }
- /** {@inheritDoc} */
- @Override
- public void modify(final EstimatedMeasurement<TurnAroundRange> estimated) {
- // the participants are master station at emission, spacecraft during leg 1,
- // slave station at rebound, spacecraft during leg 2, master station at reception
- final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
- final Vector3D pMasterEmission = participants[0].getPosition();
- final AbsoluteDate transitDateLeg1 = participants[1].getDate();
- final Vector3D pSlaveRebound = participants[2].getPosition();
- final AbsoluteDate transitDateLeg2 = participants[3].getDate();
- final Vector3D pMasterReception = participants[4].getPosition();
- // transforms from spacecraft to inertial frame at transit dates
- final SpacecraftState refState = estimated.getStates()[0];
- final SpacecraftState transitStateLeg1 = refState.shiftedBy(transitDateLeg1.durationFrom(refState.getDate()));
- final Transform spacecraftToInertLeg1 = transitStateLeg1.toTransform().getInverse();
- final SpacecraftState transitStateLeg2 = refState.shiftedBy(transitDateLeg2.durationFrom(refState.getDate()));
- final Transform spacecraftToInertLeg2 = transitStateLeg2.toTransform().getInverse();
- // compute the geometrical value of the turn-around range directly from participants positions.
- // Note that this may be different from the value returned by estimated.getEstimatedValue(),
- // because other modifiers may already have been taken into account
- final Vector3D pSpacecraftLeg1 = spacecraftToInertLeg1.transformPosition(Vector3D.ZERO);
- final Vector3D pSpacecraftLeg2 = spacecraftToInertLeg2.transformPosition(Vector3D.ZERO);
- final double turnAroundRangeUsingSpacecraftCenter =
- 0.5 * (Vector3D.distance(pMasterEmission, pSpacecraftLeg1) +
- Vector3D.distance(pSpacecraftLeg1, pSlaveRebound) +
- Vector3D.distance(pSlaveRebound, pSpacecraftLeg2) +
- Vector3D.distance(pSpacecraftLeg2, pMasterReception));
- // compute the geometrical value of the range replacing
- // the spacecraft positions with antenna phase center positions
- final Vector3D pAPCLeg1 = spacecraftToInertLeg1.transformPosition(antennaPhaseCenter);
- final Vector3D pAPCLeg2 = spacecraftToInertLeg2.transformPosition(antennaPhaseCenter);
- final double turnAroundRangeUsingAntennaPhaseCenter =
- 0.5 * (Vector3D.distance(pMasterEmission, pAPCLeg1) +
- Vector3D.distance(pAPCLeg1, pSlaveRebound) +
- Vector3D.distance(pSlaveRebound, pAPCLeg2) +
- Vector3D.distance(pAPCLeg2, pMasterReception));
- // get the estimated value before this modifier is applied
- final double[] value = estimated.getEstimatedValue();
- // modify the value
- value[0] += turnAroundRangeUsingAntennaPhaseCenter - turnAroundRangeUsingSpacecraftCenter;
- estimated.setEstimatedValue(value);
- }
- }