RelativisticClockInterSatellitesPhaseModifier.java

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package org.orekit.estimation.measurements.modifiers;

import java.util.Collections;
import java.util.List;

import org.orekit.estimation.measurements.EstimatedMeasurementBase;
import org.orekit.estimation.measurements.EstimationModifier;
import org.orekit.estimation.measurements.gnss.InterSatellitesPhase;
import org.orekit.utils.Constants;
import org.orekit.utils.ParameterDriver;

/** Class modifying theoretical inter-satellites phase measurement with relativistic clock correction.
 * <p>
 * Relativistic clock correction is caused by the motion of the satellite as well as
 * the change in the gravitational potential
 * </p>
 * @author Bryan Cazabonne
 * @since 10.3
 *
 * @see "Teunissen, Peter, and Oliver Montenbruck, eds. Springer handbook of global navigation
 * satellite systems. Chapter 19.2. Springer, 2017."
 */
public class RelativisticClockInterSatellitesPhaseModifier extends AbstractRelativisticClockModifier implements EstimationModifier<InterSatellitesPhase> {

    /** Simple constructor. */
    public RelativisticClockInterSatellitesPhaseModifier() {
        super();
    }

    /** {@inheritDoc} */
    @Override
    public List<ParameterDriver> getParametersDrivers() {
        return Collections.emptyList();
    }

    /** {@inheritDoc} */
    @Override
    public void modifyWithoutDerivatives(final EstimatedMeasurementBase<InterSatellitesPhase> estimated) {
        // Relativistic clock correction
        final double dtRel = relativisticCorrection(estimated);

        // Wavelength
        final double wavelength  = estimated.getObservedMeasurement().getWavelength();
        final double cOverLambda = Constants.SPEED_OF_LIGHT / wavelength;

        // Update estimated value taking into account the relativistic effect.
        final double[] newValue = estimated.getEstimatedValue().clone();
        newValue[0] = newValue[0] - dtRel * cOverLambda;
        estimated.modifyEstimatedValue(this, newValue);
    }

}