RelativisticJ2ClockOneWayGNSSRangeModifier.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.OneWayGNSSRange;
import org.orekit.utils.Constants;
import org.orekit.utils.ParameterDriver;
/**
* Class modifying one-way GNSS range theoretical measurements with relativistic J2 clock correction.
* <p>
* Relativistic clock correction of the effects caused by the oblateness of Earth on
* the gravity potential.
* </p>
* <p>
* The time delay caused by this effect is computed based on the orbital parameters of the
* emitter's orbit.
* </p>
*
* @author Louis Aucouturier
* @since 11.2
*
* @see "Teunissen, Peter, and Oliver Montenbruck, eds. Springer handbook of global navigation
* satellite systems. Chapter 19.2. Equation 19.18 Springer, 2017."
*/
public class RelativisticJ2ClockOneWayGNSSRangeModifier extends AbstractRelativisticJ2ClockModifier implements EstimationModifier<OneWayGNSSRange> {
/**
* Modifier constructor.
* @param gm Earth gravitational constant (mu) in m³/s².
* @param c20 Earth un-normalized second zonal coefficient (Signed J2 constant, is negative) (Typical value -1.0826e-3).
* @param equatorialRadius Earth equatorial radius in m.
*/
public RelativisticJ2ClockOneWayGNSSRangeModifier(final double gm,
final double c20,
final double equatorialRadius) {
super(gm, c20, equatorialRadius);
}
/** {@inheritDoc} */
@Override
public List<ParameterDriver> getParametersDrivers() {
return Collections.emptyList();
}
/** {@inheritDoc} */
@Override
public void modifyWithoutDerivatives(final EstimatedMeasurementBase<OneWayGNSSRange> estimated) {
// Relativistic effect
final double dtJ2 = relativisticJ2Correction(estimated);
// Update estimated value taking into account the relativistic effect.
final double[] newValue = estimated.getEstimatedValue().clone();
newValue[0] = newValue[0] - dtJ2 * Constants.SPEED_OF_LIGHT;
estimated.modifyEstimatedValue(this, newValue);
}
}