OneWayGNSSPhaseBuilder.java
/* Copyright 2002-2024 Luc Maisonobe
* 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.generation;
import java.util.Map;
import java.util.function.Function;
import java.util.function.ToDoubleFunction;
import org.hipparchus.random.CorrelatedRandomVectorGenerator;
import org.orekit.estimation.measurements.EstimationModifier;
import org.orekit.estimation.measurements.ObservableSatellite;
import org.orekit.estimation.measurements.QuadraticClockModel;
import org.orekit.estimation.measurements.gnss.AmbiguityCache;
import org.orekit.estimation.measurements.gnss.OneWayGNSSPhase;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.sampling.OrekitStepInterpolator;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.ParameterDriver;
/** Builder for {@link OneWayGNSSPhase} measurements.
* @author Luc Maisonobe
* @since 12.0
*/
public class OneWayGNSSPhaseBuilder extends AbstractMeasurementBuilder<OneWayGNSSPhase> {
/** Cache for ambiguities.
* @since 12.1
*/
private final AmbiguityCache cache;
/** Wavelength of the phase observed value [m]. */
private final double wavelength;
/** Satellite which receives the signal and performs the measurement. */
private final ObservableSatellite local;
/** Satellite which simply emits the signal. */
private final ObservableSatellite remote;
/** Clock model of the remote satellite that provides clock offset. */
private final QuadraticClockModel remoteClockModel;
/** Temporary builder for clock models.
* @deprecated this is a temporary field, it will be removed in Orekit 13.0
*/
@Deprecated
private Function<AbsoluteDate, QuadraticClockModel> clockBuilder;
/** Simple constructor.
* @param noiseSource noise source, may be null for generating perfect measurements
* @param local satellite which receives the signal and performs the measurement
* @param remote satellite which simply emits the signal
* @param remoteClockModel clock model of the remote satellite that provides clock offset
* @param wavelength phase observed value wavelength (m)
* @param sigma theoretical standard deviation
* @param baseWeight base weight
* @deprecated as of 12.1, replaced by {@link #OneWayGNSSPhaseBuilder(CorrelatedRandomVectorGenerator,
* ObservableSatellite, ObservableSatellite, QuadraticClockModel,
* double, double, double, AmbiguityCache)}
*/
@Deprecated
public OneWayGNSSPhaseBuilder(final CorrelatedRandomVectorGenerator noiseSource,
final ObservableSatellite local, final ObservableSatellite remote,
final ToDoubleFunction<AbsoluteDate> remoteClockModel,
final double wavelength, final double sigma, final double baseWeight) {
this(noiseSource, local, remote, null, wavelength, sigma, baseWeight,
AmbiguityCache.DEFAULT_CACHE);
this.clockBuilder = date -> {
final double cM = remoteClockModel.applyAsDouble(date.shiftedBy(-1));
final double c0 = remoteClockModel.applyAsDouble(date);
final double cP = remoteClockModel.applyAsDouble(date.shiftedBy(1));
return new QuadraticClockModel(date, c0, 0.5 * (cP - cM), 0.5 * (cP + cM) - c0);
};
}
/** Simple constructor.
* @param noiseSource noise source, may be null for generating perfect measurements
* @param local satellite which receives the signal and performs the measurement
* @param remote satellite which simply emits the signal
* @param remoteClockModel clock model of the remote satellite that provides clock offset
* @param wavelength phase observed value wavelength (m)
* @param sigma theoretical standard deviation
* @param baseWeight base weight
* @param cache from which ambiguity drive should come
* @since 12.1
*/
public OneWayGNSSPhaseBuilder(final CorrelatedRandomVectorGenerator noiseSource,
final ObservableSatellite local, final ObservableSatellite remote,
final QuadraticClockModel remoteClockModel,
final double wavelength, final double sigma, final double baseWeight,
final AmbiguityCache cache) {
super(noiseSource, sigma, baseWeight, local, remote);
this.wavelength = wavelength;
this.local = local;
this.remote = remote;
this.remoteClockModel = remoteClockModel;
this.cache = cache;
}
/** {@inheritDoc} */
@Override
public OneWayGNSSPhase build(final AbsoluteDate date,
final Map<ObservableSatellite, OrekitStepInterpolator> interpolators) {
final double sigma = getTheoreticalStandardDeviation()[0];
final double baseWeight = getBaseWeight()[0];
final SpacecraftState[] relevant = new SpacecraftState[] {
interpolators.get(local).getInterpolatedState(date),
interpolators.get(remote).getInterpolatedState(date)
};
// temporary hack to build QuadraticClockModel from ToDoubleFunction<AbsoluteDate>
// for compatibility purposes
final QuadraticClockModel clockModel = remoteClockModel != null ?
remoteClockModel :
clockBuilder.apply(date);
// create a dummy measurement
final OneWayGNSSPhase dummy = new OneWayGNSSPhase(interpolators.get(remote),
remote.getName(),
clockModel, date,
Double.NaN, wavelength,
sigma, baseWeight, local,
cache);
for (final EstimationModifier<OneWayGNSSPhase> modifier : getModifiers()) {
dummy.addModifier(modifier);
}
// set a reference date for parameters missing one
for (final ParameterDriver driver : dummy.getParametersDrivers()) {
if (driver.getReferenceDate() == null) {
final AbsoluteDate start = getStart();
final AbsoluteDate end = getEnd();
driver.setReferenceDate(start.durationFrom(end) <= 0 ? start : end);
}
}
// estimate the perfect value of the measurement
double phase = dummy.estimateWithoutDerivatives(relevant).getEstimatedValue()[0];
// add the noise
final double[] noise = getNoise();
if (noise != null) {
phase += noise[0];
}
// generate measurement
final OneWayGNSSPhase measurement = new OneWayGNSSPhase(interpolators.get(remote),
remote.getName(),
clockModel, date,
phase, wavelength, sigma, baseWeight, local,
cache);
for (final EstimationModifier<OneWayGNSSPhase> modifier : getModifiers()) {
measurement.addModifier(modifier);
}
return measurement;
}
}