OnBoardAntennaOneWayGNSSRangeModifier.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.attitudes.AttitudeProvider;
- import org.orekit.estimation.measurements.EstimatedMeasurement;
- import org.orekit.estimation.measurements.EstimationModifier;
- import org.orekit.estimation.measurements.gnss.OneWayGNSSRange;
- import org.orekit.frames.Transform;
- import org.orekit.orbits.CartesianOrbit;
- import org.orekit.orbits.Orbit;
- 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 one-way GNSS range measurements.
- * @author Bryan Cazabonne
- * @since 10.3
- */
- public class OnBoardAntennaOneWayGNSSRangeModifier implements EstimationModifier<OneWayGNSSRange> {
- /** Position of the Antenna Phase Center in satellite 1 frame. */
- private final Vector3D antennaPhaseCenter1;
- /** Position of the Antenna Phase Center in satellite 2 frame. */
- private final Vector3D antennaPhaseCenter2;
- /** Attitude provider of the emitting satellite. */
- private final AttitudeProvider attitude;
- /** Simple constructor.
- * @param antennaPhaseCenter1 position of the Antenna Phase Center in satellite 1 frame
- * (i.e. the satellite which receives the signal and performs the measurement)
- * @param antennaPhaseCenter2 position of the Antenna Phase Center in satellite 2 frame
- * (i.e. the satellite which simply emits the signal)
- * @param attitude attitude provider of the emitting satellite
- */
- public OnBoardAntennaOneWayGNSSRangeModifier(final Vector3D antennaPhaseCenter1,
- final Vector3D antennaPhaseCenter2,
- final AttitudeProvider attitude) {
- this.antennaPhaseCenter1 = antennaPhaseCenter1;
- this.antennaPhaseCenter2 = antennaPhaseCenter2;
- this.attitude = attitude;
- }
- /** {@inheritDoc} */
- @Override
- public List<ParameterDriver> getParametersDrivers() {
- return Collections.emptyList();
- }
- /** {@inheritDoc} */
- @Override
- public void modify(final EstimatedMeasurement<OneWayGNSSRange> estimated) {
- // The participants are remote satellite at emission, local satellite at reception
- final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
- final AbsoluteDate emissionDate = participants[0].getDate();
- final AbsoluteDate receptionDate = participants[1].getDate();
- // Transforms from spacecraft to inertial frame at reception date
- final SpacecraftState refStateLocal = estimated.getStates()[0];
- final SpacecraftState receptionState = refStateLocal.shiftedBy(receptionDate.durationFrom(refStateLocal.getDate()));
- final Transform receptionSpacecraftToInert = receptionState.toTransform().getInverse();
- // Orbit of the remote satellite
- final Orbit orbitRemote = new CartesianOrbit(participants[0], refStateLocal.getFrame(), receptionState.getMu());
- // Transforms from spacecraft to inertial frame at emission date
- final SpacecraftState refStateRemote = new SpacecraftState(orbitRemote,
- attitude.getAttitude(orbitRemote,
- orbitRemote.getDate(),
- orbitRemote.getFrame()));
- final SpacecraftState emissionState = refStateRemote.shiftedBy(emissionDate.durationFrom(refStateRemote.getDate()));
- final Transform emissionSpacecraftToInert = emissionState.toTransform().getInverse();
- // Compute the geometrical value of the one-way GNSS 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 pSpacecraftReception = receptionSpacecraftToInert.transformPosition(Vector3D.ZERO);
- final Vector3D pSpacecraftEmission = emissionSpacecraftToInert.transformPosition(Vector3D.ZERO);
- final double oneWayGNSSRangeUsingSpacecraftCenter = Vector3D.distance(pSpacecraftEmission, pSpacecraftReception);
- // Compute the geometrical value of the range replacing
- // the spacecraft positions with antenna phase center positions
- final Vector3D pAPCReception = receptionSpacecraftToInert.transformPosition(antennaPhaseCenter1);
- final Vector3D pAPCEmission = emissionSpacecraftToInert.transformPosition(antennaPhaseCenter2);
- final double oneWayGNSSRangeUsingAntennaPhaseCenter = Vector3D.distance(pAPCEmission, pAPCReception);
- // Get the estimated value before this modifier is applied
- final double[] value = estimated.getEstimatedValue();
- // Modify the value
- value[0] += oneWayGNSSRangeUsingAntennaPhaseCenter - oneWayGNSSRangeUsingSpacecraftCenter;
- estimated.setEstimatedValue(value);
- }
- }