ShapiroOneWayGNSSPhaseModifier.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.OneWayGNSSPhase;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TimeStampedPVCoordinates;

/** Class modifying theoretical one-way GNSS phase measurement with Shapiro time delay.
 * <p>
 * Shapiro time delay is a relativistic effect due to gravity.
 * </p>
 * @author Bryan Cazabonne
 * @since 10.3
 */
public class ShapiroOneWayGNSSPhaseModifier extends AbstractShapiroBaseModifier implements EstimationModifier<OneWayGNSSPhase> {

    /** Simple constructor.
     * @param gm gravitational constant for main body in signal path vicinity.
     */
    public ShapiroOneWayGNSSPhaseModifier(final double gm) {
        super(gm);
    }

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

    /** {@inheritDoc} */
    @Override
    public void modifyWithoutDerivatives(final EstimatedMeasurementBase<OneWayGNSSPhase> estimated) {
        // Compute correction
        final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
        final double phaseCorrection = shapiroCorrection(participants[0], participants[1]);
        // Update estimated value taking into account the Shapiro time delay.
        final double wavelength = estimated.getObservedMeasurement().getWavelength();
        final double[] newValue = estimated.getEstimatedValue().clone();
        newValue[0] = newValue[0] + (phaseCorrection / wavelength);
        estimated.modifyEstimatedValue(this, newValue);
    }

}