Skip to content

GitLab

Commit e2c7ab7e authored by Bryan Cazabonne's avatar Bryan Cazabonne
Browse files
Options

Allowed dynamic station coordinates when calculating tropospheric delay. 

Fixes #624
parent 1d1a03ba
Pipeline #911 passed with stage
    in 23 minutes and 49 seconds
    Hide whitespace changes
    Inline Side-by-side
    Showing with 852 additions and 759 deletions
    src/changes/changes.xml
    View file @ e2c7ab7e
    ......@@ -21,6 +21,9 @@
    </properties>
    <body>
    <release version="11.0" date="TBD" description="TBD">
    <action dev="bryan" type="fix" issue="624">
    Allowed dynamic station coordinates when calculating tropospheric delay.
    </action>
    <action dev="bryan" type="update" issue="755">
    Modified IodGooding constructor to be consistent with other IOD methods.
    </action>
    ......
    src/main/java/org/orekit/estimation/measurements/modifiers/AngularTroposphericDelayModifier.java
    View file @ e2c7ab7e
    ......@@ -56,17 +56,6 @@ public class AngularTroposphericDelayModifier implements EstimationModifier<Angu
    tropoModel = model;
    }
    /** Get the station height above mean sea level.
    *
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private double getStationHeightAMSL(final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final double height = station.getBaseFrame().getPoint().getAltitude();
    return height;
    }
    /** Compute the measurement error due to Troposphere.
    * @param station station
    * @param state spacecraft state
    ......@@ -84,11 +73,8 @@ public class AngularTroposphericDelayModifier implements EstimationModifier<Angu
    // only consider measures above the horizon
    if (elevation > 0.0) {
    // altitude AMSL in meters
    final double height = getStationHeightAMSL(station);
    // delay in meters
    final double delay = tropoModel.pathDelay(elevation, height, tropoModel.getParameters(), state.getDate());
    final double delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state.getDate());
    // one-way measurement.
    return delay;
    ......
    src/main/java/org/orekit/estimation/measurements/modifiers/PhaseTroposphericDelayModifier.java
    View file @ e2c7ab7e
    ......@@ -54,30 +54,7 @@ public class PhaseTroposphericDelayModifier implements EstimationModifier<Phase>
    * @param model Tropospheric delay model appropriate for the current range measurement method.
    */
    public PhaseTroposphericDelayModifier(final DiscreteTroposphericModel model) {
    tropoModel = model;
    }
    /** Get the station height above mean sea level.
    *
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private double getStationHeightAMSL(final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final double height = station.getBaseFrame().getPoint().getAltitude();
    return height;
    }
    /** Get the station height above mean sea level.
    * @param <T> type of the elements
    * @param field field of the elements
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private <T extends RealFieldElement<T>> T getStationHeightAMSL(final Field<T> field, final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final T height = station.getBaseFrame().getPoint(field).getAltitude();
    return height;
    tropoModel = model;
    }
    /** Compute the measurement error due to Troposphere.
    ......@@ -97,11 +74,8 @@ public class PhaseTroposphericDelayModifier implements EstimationModifier<Phase>
    // only consider measures above the horizon
    if (elevation > 0) {
    // altitude AMSL in meters
    final double height = getStationHeightAMSL(station);
    // delay in meters
    final double delay = tropoModel.pathDelay(elevation, height, tropoModel.getParameters(), state.getDate());
    final double delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state.getDate());
    return delay / wavelength;
    }
    ......@@ -134,11 +108,8 @@ public class PhaseTroposphericDelayModifier implements EstimationModifier<Phase>
    // only consider measures above the horizon
    if (elevation.getReal() > 0) {
    // altitude AMSL in meters
    final T height = getStationHeightAMSL(field, station);
    // delay in meters
    final T delay = tropoModel.pathDelay(elevation, height, parameters, state.getDate());
    final T delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(field), parameters, state.getDate());
    return delay.divide(wavelength);
    }
    ......
    src/main/java/org/orekit/estimation/measurements/modifiers/RangeRateTroposphericDelayModifier.java
    View file @ e2c7ab7e
    ......@@ -69,29 +69,6 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    }
    }
    /** Get the station height above mean sea level.
    *
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private double getStationHeightAMSL(final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final double height = station.getBaseFrame().getPoint().getAltitude();
    return height;
    }
    /** Get the station height above mean sea level.
    * @param <T> type of the element
    * @param field field of the elements
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private <T extends RealFieldElement<T>> T getStationHeightAMSL(final Field<T> field, final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final T height = station.getBaseFrame().getPoint(field).getAltitude();
    return height;
    }
    /** Compute the measurement error due to Troposphere.
    * @param station station
    * @param state spacecraft state
    ......@@ -104,9 +81,6 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    final double dt = 10; // s
    // station altitude AMSL in meters
    final double height = getStationHeightAMSL(station);
    // spacecraft position and elevation as seen from the ground station
    final Vector3D position = state.getPVCoordinates().getPosition();
    ......@@ -118,7 +92,7 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    // only consider measures above the horizon
    if (elevation1 > 0) {
    // tropospheric delay in meters
    final double d1 = tropoModel.pathDelay(elevation1, height, tropoModel.getParameters(), state.getDate());
    final double d1 = tropoModel.pathDelay(elevation1, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state.getDate());
    // propagate spacecraft state forward by dt
    final SpacecraftState state2 = state.shiftedBy(dt);
    ......@@ -132,7 +106,7 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    state2.getDate());
    // tropospheric delay dt after
    final double d2 = tropoModel.pathDelay(elevation2, height, tropoModel.getParameters(), state2.getDate());
    final double d2 = tropoModel.pathDelay(elevation2, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state2.getDate());
    return fTwoWay * (d2 - d1) / dt;
    }
    ......@@ -160,9 +134,6 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    final double dt = 10; // s
    // station altitude AMSL in meters
    final T height = getStationHeightAMSL(field, station);
    // spacecraft position and elevation as seen from the ground station
    final FieldVector3D<T> position = state.getPVCoordinates().getPosition();
    final T elevation1 = station.getBaseFrame().getElevation(position,
    ......@@ -172,7 +143,7 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    // only consider measures above the horizon
    if (elevation1.getReal() > 0) {
    // tropospheric delay in meters
    final T d1 = tropoModel.pathDelay(elevation1, height, parameters, state.getDate());
    final T d1 = tropoModel.pathDelay(elevation1, station.getBaseFrame().getPoint(field), parameters, state.getDate());
    // propagate spacecraft state forward by dt
    final FieldSpacecraftState<T> state2 = state.shiftedBy(dt);
    ......@@ -187,7 +158,7 @@ public class RangeRateTroposphericDelayModifier implements EstimationModifier<Ra
    // tropospheric delay dt after
    final T d2 = tropoModel.pathDelay(elevation2, height, parameters, state2.getDate());
    final T d2 = tropoModel.pathDelay(elevation2, station.getBaseFrame().getPoint(field), parameters, state2.getDate());
    return (d2.subtract(d1)).divide(dt).multiply(fTwoWay);
    }
    ......
    src/main/java/org/orekit/estimation/measurements/modifiers/RangeTroposphericDelayModifier.java
    View file @ e2c7ab7e
    ......@@ -60,29 +60,6 @@ public class RangeTroposphericDelayModifier implements EstimationModifier<Range>
    tropoModel = model;
    }
    /** Get the station height above mean sea level.
    *
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private double getStationHeightAMSL(final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final double height = station.getBaseFrame().getPoint().getAltitude();
    return height;
    }
    /** Get the station height above mean sea level.
    * @param <T> type of the elements
    * @param field field of the elements
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private <T extends RealFieldElement<T>> T getStationHeightAMSL(final Field<T> field, final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final T height = station.getBaseFrame().getPoint(field).getAltitude();
    return height;
    }
    /** Compute the measurement error due to Troposphere.
    * @param station station
    * @param state spacecraft state
    ......@@ -99,11 +76,8 @@ public class RangeTroposphericDelayModifier implements EstimationModifier<Range>
    // only consider measures above the horizon
    if (elevation > 0) {
    // altitude AMSL in meters
    final double height = getStationHeightAMSL(station);
    // delay in meters
    final double delay = tropoModel.pathDelay(elevation, height, tropoModel.getParameters(), state.getDate());
    final double delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state.getDate());
    return delay;
    }
    ......@@ -135,11 +109,8 @@ public class RangeTroposphericDelayModifier implements EstimationModifier<Range>
    // only consider measures above the horizon
    if (elevation.getReal() > 0) {
    // altitude AMSL in meters
    final T height = getStationHeightAMSL(field, station);
    // delay in meters
    final T delay = tropoModel.pathDelay(elevation, height, parameters, state.getDate());
    final T delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(field), parameters, state.getDate());
    return delay;
    }
    ......
    src/main/java/org/orekit/estimation/measurements/modifiers/TurnAroundRangeTroposphericDelayModifier.java
    View file @ e2c7ab7e
    ......@@ -59,30 +59,6 @@ public class TurnAroundRangeTroposphericDelayModifier implements EstimationModif
    tropoModel = model;
    }
    /** Get the station height above mean sea level.
    *
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private double getStationHeightAMSL(final GroundStation station) {
    // FIXME height should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final double height = station.getBaseFrame().getPoint().getAltitude();
    return height;
    }
    /** Get the station height above mean sea level.
    * @param <T> type of the elements
    * @param field field of the elements
    * @param station ground station (or measuring station)
    * @return the measuring station height above sea level, m
    */
    private <T extends RealFieldElement<T>> T getStationHeightAMSL(final Field<T> field,
    final GroundStation station) {
    // FIXME heigth should be computed with respect to geoid WGS84+GUND = EGM2008 for example
    final T height = station.getBaseFrame().getPoint(field).getAltitude();
    return height;
    }
    /** Compute the measurement error due to Troposphere.
    * @param station station
    * @param state spacecraft state
    ......@@ -99,11 +75,8 @@ public class TurnAroundRangeTroposphericDelayModifier implements EstimationModif
    // only consider measures above the horizon
    if (elevation > 0) {
    // altitude AMSL in meters
    final double height = getStationHeightAMSL(station);
    // Delay in meters
    final double delay = tropoModel.pathDelay(elevation, height, tropoModel.getParameters(), state.getDate());
    final double delay = tropoModel.pathDelay(elevation, station.getBaseFrame().getPoint(), tropoModel.getParameters(), state.getDate());
    return delay;
    }
    ......@@ -133,11 +106,8 @@ public class TurnAroundRangeTroposphericDelayModifier implements EstimationModif
    // only consider measures above the horizon
    if (dsElevation.getReal() > 0) {
    // altitude AMSL in meters
    final T height = getStationHeightAMSL(field, station);
    // Delay in meters
    final T delay = tropoModel.pathDelay(dsElevation, height, parameters, state.getDate());
    final T delay = tropoModel.pathDelay(dsElevation, station.getBaseFrame().getPoint(field), parameters, state.getDate());
    return delay;
    }
    ......
    src/main/java/org/orekit/models/earth/troposphere/DiscreteTroposphericModel.java
    View file @ e2c7ab7e
    ......@@ -17,6 +17,8 @@
    package org.orekit.models.earth.troposphere;
    import org.hipparchus.RealFieldElement;
    import org.orekit.bodies.FieldGeodeticPoint;
    import org.orekit.bodies.GeodeticPoint;
    import org.orekit.time.AbsoluteDate;
    import org.orekit.time.FieldAbsoluteDate;
    ......@@ -41,24 +43,24 @@ public interface DiscreteTroposphericModel extends MappingFunction {
    * station to a satellite.
    *
    * @param elevation the elevation of the satellite, in radians
    * @param height the height of the station in m above sea level
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return the path delay due to the troposphere in m
    */
    double pathDelay(double elevation, double height, double[] parameters, AbsoluteDate date);
    double pathDelay(double elevation, GeodeticPoint point, double[] parameters, AbsoluteDate date);
    /** Calculates the tropospheric path delay for the signal path from a ground
    * station to a satellite.
    *
    * @param <T> type of the elements
    * @param elevation the elevation of the satellite, in radians
    * @param height the height of the station in m above sea level
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return the path delay due to the troposphere in m
    */
    <T extends RealFieldElement<T>> T pathDelay(T elevation, T height, T[] parameters, FieldAbsoluteDate<T> date);
    <T extends RealFieldElement<T>> T pathDelay(T elevation, FieldGeodeticPoint<T> point, T[] parameters, FieldAbsoluteDate<T> date);
    /** This method allows the computation of the zenith hydrostatic and
    * zenith wet delay. The resulting element is an array having the following form:
    ......@@ -66,12 +68,12 @@ public interface DiscreteTroposphericModel extends MappingFunction {
    * <li>double[0] = D<sub>hz</sub> → zenith hydrostatic delay
    * <li>double[1] = D<sub>wz</sub> → zenith wet delay
    * </ul>
    * @param height the height of the station in m above sea level.
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return a two components array containing the zenith hydrostatic and wet delays.
    */
    double[] computeZenithDelay(double height, double[] parameters, AbsoluteDate date);
    double[] computeZenithDelay(GeodeticPoint point, double[] parameters, AbsoluteDate date);
    /** This method allows the computation of the zenith hydrostatic and
    * zenith wet delay. The resulting element is an array having the following form:
    ......@@ -80,11 +82,11 @@ public interface DiscreteTroposphericModel extends MappingFunction {
    * <li>T[1] = D<sub>wz</sub> → zenith wet delay
    * </ul>
    * @param <T> type of the elements
    * @param height the height of the station in m above sea level.
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return a two components array containing the zenith hydrostatic and wet delays.
    */
    <T extends RealFieldElement<T>> T[] computeZenithDelay(T height, T[] parameters, FieldAbsoluteDate<T> date);
    <T extends RealFieldElement<T>> T[] computeZenithDelay(FieldGeodeticPoint<T> point, T[] parameters, FieldAbsoluteDate<T> date);
    }
    src/main/java/org/orekit/models/earth/troposphere/EstimatedTroposphericModel.java
    View file @ e2c7ab7e
    ......@@ -23,6 +23,8 @@ import org.hipparchus.Field;
    import org.hipparchus.RealFieldElement;
    import org.hipparchus.util.FastMath;
    import org.hipparchus.util.MathArrays;
    import org.orekit.bodies.FieldGeodeticPoint;
    import org.orekit.bodies.GeodeticPoint;
    import org.orekit.time.AbsoluteDate;
    import org.orekit.time.FieldAbsoluteDate;
    import org.orekit.utils.ParameterDriver;
    ......@@ -41,7 +43,7 @@ import org.orekit.utils.ParameterDriver;
    * <p>
    * The mapping functions m<sub>h</sub>(e) and m<sub>w</sub>(e) are
    * computed thanks to a {@link #model} initialized by the user.
    * The user has the possiblility to use several mapping function models for the computations:
    * The user has the possibility to use several mapping function models for the computations:
    * the {@link GlobalMappingFunctionModel Global Mapping Function}, or
    * the {@link NiellMappingFunctionModel Niell Mapping Function}
    * </p> <p>
    ......@@ -94,43 +96,48 @@ public class EstimatedTroposphericModel implements DiscreteTroposphericModel {
    this(273.15 + 18.0, 1013.25, model, totalDelay);
    }
    /** {@inheritDoc} */
    @Override
    public double[] mappingFactors(final double elevation, final double height,
    public double[] mappingFactors(final double elevation, final GeodeticPoint point,
    final double[] parameters, final AbsoluteDate date) {
    return model.mappingFactors(elevation, height, parameters, date);
    return model.mappingFactors(elevation, point, parameters, date);
    }
    /** {@inheritDoc} */
    @Override
    public <T extends RealFieldElement<T>> T[] mappingFactors(final T elevation, final T height,
    public <T extends RealFieldElement<T>> T[] mappingFactors(final T elevation, final FieldGeodeticPoint<T> point,
    final T[] parameters, final FieldAbsoluteDate<T> date) {
    return model.mappingFactors(elevation, height, parameters, date);
    return model.mappingFactors(elevation, point, parameters, date);
    }
    /** {@inheritDoc} */
    @Override
    public List<ParameterDriver> getParametersDrivers() {
    return Collections.singletonList(totalZenithDelay);
    }
    /** {@inheritDoc} */
    @Override
    public double pathDelay(final double elevation, final double height,
    public double pathDelay(final double elevation, final GeodeticPoint point,
    final double[] parameters, final AbsoluteDate date) {
    // Mapping functions
    final double[] mf = mappingFactors(elevation, height, parameters, date);
    final double[] mf = mappingFactors(elevation, point, parameters, date);
    // Zenith delays
    final double[] delays = computeZenithDelay(height, parameters, date);
    final double[] delays = computeZenithDelay(point, parameters, date);
    // Total delay
    return mf[0] * delays[0] + mf[1] * (delays[1] - delays[0]);
    }
    /** {@inheritDoc} */
    @Override
    public <T extends RealFieldElement<T>> T pathDelay(final T elevation, final T height,
    public <T extends RealFieldElement<T>> T pathDelay(final T elevation, final FieldGeodeticPoint<T> point,
    final T[] parameters, final FieldAbsoluteDate<T> date) {
    // Mapping functions
    final T[] mf = mappingFactors(elevation, height, parameters, date);
    final T[] mf = mappingFactors(elevation, point, parameters, date);
    // Zenith delays
    final T[] delays = computeZenithDelay(height, parameters, date);
    final T[] delays = computeZenithDelay(point, parameters, date);
    // Total delay
    return mf[0].multiply(delays[0]).add(mf[1].multiply(delays[1].subtract(delays[0])));
    }
    ......@@ -145,19 +152,20 @@ public class EstimatedTroposphericModel implements DiscreteTroposphericModel {
    * The user have to be careful because the others tropospheric models in Orekit
    * compute the zenith wet delay instead of the total zenith delay.
    * </p>
    * @param height the height of the station in m above sea level.
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return a two components array containing the zenith hydrostatic and wet delays.
    */
    public double[] computeZenithDelay(final double height, final double[] parameters,
    @Override
    public double[] computeZenithDelay(final GeodeticPoint point, final double[] parameters,
    final AbsoluteDate date) {
    // Use an empirical model for tropospheric zenith hydro-static delay : Saastamoinen model
    final SaastamoinenModel saastamoinen = new SaastamoinenModel(t0, p0, 0.0);
    // elevation = pi/2 because we compute the delay in the zenith direction
    final double zhd = saastamoinen.pathDelay(0.5 * FastMath.PI, height, parameters, date);
    final double zhd = saastamoinen.computeZenithDelay(point, parameters, date)[0];
    final double ztd = parameters[0];
    return new double[] {
    ......@@ -177,23 +185,23 @@ public class EstimatedTroposphericModel implements DiscreteTroposphericModel {
    * compute the zenith wet delay instead of the total zenith delay.
    * </p>
    * @param <T> type of the elements
    * @param height the height of the station in m above sea level.
    * @param parameters tropospheric model parameters.
    * @param point station location
    * @param parameters tropospheric model parameters
    * @param date current date
    * @return a two components array containing the zenith hydrostatic and wet delays.
    */
    public <T extends RealFieldElement<T>> T[] computeZenithDelay(final T height, final T[] parameters,
    @Override
    public <T extends RealFieldElement<T>> T[] computeZenithDelay(final FieldGeodeticPoint<T> point, final T[] parameters,
    final FieldAbsoluteDate<T> date) {
    // Field
    final Field<T> field = date.getField();
    final T zero = field.getZero();
    // Use an empirical model for tropospheric zenith hydro-static delay : Saastamoinen model
    final SaastamoinenModel saastamoinen = new SaastamoinenModel(t0, p0, 0.0);
    // elevation = pi/2 because we compute the delay in the zenith direction
    final T zhd = saastamoinen.pathDelay(zero.add(0.5 * FastMath.PI), height, parameters, date);
    final T zhd = saastamoinen.computeZenithDelay(point, parameters, date)[0];
    final T ztd = parameters[0];
    final T[] delays = MathArrays.buildArray(field, 2);
    ......
    src/main/java/org/orekit/models/earth/troposphere/FixedTroposphericDelay.java
    View file @ e2c7ab7e
    ......@@ -26,6 +26,8 @@ import org.hipparchus.analysis.interpolation.PiecewiseBicubicSplineInterpolator;
    import org.hipparchus.util.FastMath;
    import org.hipparchus.util.MathArrays;
    import org.orekit.annotation.DefaultDataContext;
    import org.orekit.bodies.FieldGeodeticPoint;
    import org.orekit.bodies.GeodeticPoint;
    import org.orekit.data.DataContext;
    import org.orekit.data.DataProvidersManager;
    import org.orekit.errors.OrekitException;
    ......@@ -127,10 +129,11 @@ public class FixedTroposphericDelay implements DiscreteTroposphericModel {
    }
    /** {@inheritDoc} */
    public double pathDelay(final double elevation, final double height,
    @Override
    public double pathDelay(final double elevation, final GeodeticPoint point,
    final double[] parameters, final AbsoluteDate date) {
    // limit the height to 5000 m
    final double h = FastMath.min(FastMath.max(0, height), 5000);
    final double h = FastMath.min(FastMath.max(0, point.getAltitude()), 5000);
    // limit the elevation to 0 - π
    final double ele = FastMath.min(FastMath.PI, FastMath.max(0d, elevation));
    // mirror elevation at the right angle of π/2
    ......@@ -140,11 +143,12 @@ public class FixedTroposphericDelay implements DiscreteTroposphericModel {
    }
    /** {@inheritDoc} */
    public <T extends RealFieldElement<T>> T pathDelay(final T elevation, final T height,
    @Override
    public <T extends RealFieldElement<T>> T pathDelay(final T elevation, final FieldGeodeticPoint<T> point,
    final T[] parameters, final FieldAbsoluteDate<T> date) {
    final T zero = height.getField().getZero();
    final T zero = date.getField().getZero();
    // limit the height to 5000 m
    final T h = FastMath.min(FastMath.max(zero, height), zero.add(5000));
    final T h = FastMath.min(FastMath.max(zero, point.getAltitude()), zero.add(5000));
    // limit the elevation to 0 - π
    final T ele = FastMath.min(zero.add(FastMath.PI), FastMath.max(zero, elevation));
    // mirror elevation at the right angle of π/2
    ......@@ -153,28 +157,31 @@ public class FixedTroposphericDelay implements DiscreteTroposphericModel {
    return delayFunction.value(h, e);
    }
    /** {@inheritDoc} */
    @Override
    public double[] computeZenithDelay(final double height, final double[] parameters,
    public double[] computeZenithDelay(final GeodeticPoint point, final double[] parameters,
    final AbsoluteDate date) {
    return new double[] {
    pathDelay(0.5 * FastMath.PI, height, parameters, date),
    pathDelay(0.5 * FastMath.PI, point, parameters, date),
    0.
    };
    }