OnBoardAntennaRangeModifier.java
- /* Copyright 2002-2022 CS GROUP
- * Licensed to CS GROUP (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.Range;
- 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 range measurements.
- * @author Luc Maisonobe
- * @since 9.0
- */
- public class OnBoardAntennaRangeModifier implements EstimationModifier<Range> {
- /** 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 OnBoardAntennaRangeModifier(final Vector3D antennaPhaseCenter) {
- this.antennaPhaseCenter = antennaPhaseCenter;
- }
- /** {@inheritDoc} */
- @Override
- public List<ParameterDriver> getParametersDrivers() {
- return Collections.emptyList();
- }
- /** {@inheritDoc} */
- @Override
- public void modify(final EstimatedMeasurement<Range> estimated) {
- if (estimated.getObservedMeasurement().isTwoWay()) {
- modifyTwoWay(estimated);
- } else {
- modifyOneWay(estimated);
- }
- }
- /** Apply a modifier to a one-way range measurement.
- * @param estimated estimated measurement to modify
- */
- private void modifyOneWay(final EstimatedMeasurement<Range> estimated) {
- // the participants are spacecraft at emission, ground station at reception
- final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
- final AbsoluteDate emissionDate = participants[0].getDate();
- final Vector3D pReception = participants[1].getPosition();
- // transform from spacecraft to inertial frame at emission date
- final SpacecraftState refState = estimated.getStates()[0];
- final SpacecraftState emissionState = refState.shiftedBy(emissionDate.durationFrom(refState.getDate()));
- final Transform spacecraftToInert = emissionState.toTransform().getInverse();
- // compute the geometrical value of the 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 pSpacecraft = spacecraftToInert.transformPosition(Vector3D.ZERO);
- final double rangeUsingSpacecraftCenter = Vector3D.distance(pSpacecraft, pReception);
- // compute the geometrical value of the range replacing
- // the spacecraft position with antenna phase center position
- final Vector3D pAPC = spacecraftToInert.transformPosition(antennaPhaseCenter);
- final double rangeUsingAntennaPhaseCenter = Vector3D.distance(pAPC, pReception);
- // get the estimated value before this modifier is applied
- final double[] value = estimated.getEstimatedValue();
- // modify the value
- value[0] += rangeUsingAntennaPhaseCenter - rangeUsingSpacecraftCenter;
- estimated.setEstimatedValue(value);
- }
- /** Apply a modifier to a two-way range measurement.
- * @param estimated estimated measurement to modify
- */
- private void modifyTwoWay(final EstimatedMeasurement<Range> estimated) {
- // the participants are ground station at emission, spacecraft, ground station at reception
- // or spacecraft, ground station at reception if oneWay
- final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
- final Vector3D pEmission = participants[0].getPosition();
- final AbsoluteDate transitDate = participants[1].getDate();
- final Vector3D pReception = participants[2].getPosition();
- // transform from spacecraft to inertial frame at transit date
- final SpacecraftState refState = estimated.getStates()[0];
- final SpacecraftState transitState = refState.shiftedBy(transitDate.durationFrom(refState.getDate()));
- final Transform spacecraftToInert = transitState.toTransform().getInverse();
- // compute the geometrical value of the 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 pSpacecraft = spacecraftToInert.transformPosition(Vector3D.ZERO);
- final double rangeUsingSpacecraftCenter =
- 0.5 * (Vector3D.distance(pEmission, pSpacecraft) + Vector3D.distance(pSpacecraft, pReception));
- // compute the geometrical value of the range replacing
- // the spacecraft position with antenna phase center position
- final Vector3D pAPC = spacecraftToInert.transformPosition(antennaPhaseCenter);
- final double rangeUsingAntennaPhaseCenter =
- 0.5 * (Vector3D.distance(pEmission, pAPC) + Vector3D.distance(pAPC, pReception));
- // get the estimated value before this modifier is applied
- final double[] value = estimated.getEstimatedValue();
- // modify the value
- value[0] += rangeUsingAntennaPhaseCenter - rangeUsingSpacecraftCenter;
- estimated.setEstimatedValue(value);
- }
- }