AbstractVienna.java
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package org.orekit.models.earth.troposphere;
import java.util.Collections;
import java.util.List;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.FieldSinCos;
import org.hipparchus.util.SinCos;
import org.orekit.bodies.FieldGeodeticPoint;
import org.orekit.bodies.GeodeticPoint;
import org.orekit.models.earth.weather.FieldPressureTemperatureHumidity;
import org.orekit.models.earth.weather.PressureTemperatureHumidity;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.time.TimeScale;
import org.orekit.utils.FieldTrackingCoordinates;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TrackingCoordinates;
/** The Vienna tropospheric delay model for radio techniques.
* @since 12.1
* @author Bryan Cazabonne
* @author Luc Maisonobe
*/
public abstract class AbstractVienna implements TroposphericModel, TroposphereMappingFunction {
/** C coefficient from Chen and Herring gradient mapping function.
* @see "Modeling tropospheric delays for space geodetic techniques, Daniel Landskron, 2017, section 2.2"
*/
private static final double C = 0.0032;
/** Provider for a<sub>h</sub> and a<sub>w</sub> coefficients. */
private final ViennaAProvider aProvider;
/** Provider for {@link AzimuthalGradientCoefficients} and {@link FieldAzimuthalGradientCoefficients}. */
private final AzimuthalGradientProvider gProvider;
/** Provider for zenith delays. */
private final TroposphericModel zenithDelayProvider;
/** UTC time scale. */
private final TimeScale utc;
/** Build a new instance.
* @param aProvider provider for a<sub>h</sub> and a<sub>w</sub> coefficients
* @param gProvider provider for {@link AzimuthalGradientCoefficients} and {@link FieldAzimuthalGradientCoefficients}
* @param zenithDelayProvider provider for zenith delays
* @param utc UTC time scale
*/
protected AbstractVienna(final ViennaAProvider aProvider,
final AzimuthalGradientProvider gProvider,
final TroposphericModel zenithDelayProvider,
final TimeScale utc) {
this.aProvider = aProvider;
this.gProvider = gProvider;
this.zenithDelayProvider = zenithDelayProvider;
this.utc = utc;
}
/** {@inheritDoc} */
@Override
public TroposphericDelay pathDelay(final TrackingCoordinates trackingCoordinates,
final GeodeticPoint point,
final PressureTemperatureHumidity weather,
final double[] parameters, final AbsoluteDate date) {
// zenith delay
final TroposphericDelay delays =
zenithDelayProvider.pathDelay(trackingCoordinates, point, weather, parameters, date);
// mapping function
final double[] mappingFunction =
mappingFactors(trackingCoordinates, point, weather, date);
// horizontal gradient
final AzimuthalGradientCoefficients agc = gProvider.getGradientCoefficients(point, date);
final double gh;
final double gw;
if (agc != null) {
// Chen and Herring gradient mapping function
final double sinE = FastMath.sin(trackingCoordinates.getElevation());
final double tanE = FastMath.tan(trackingCoordinates.getElevation());
final double mfh = 1.0 / (sinE * tanE + C);
final SinCos sc = FastMath.sinCos(trackingCoordinates.getAzimuth());
gh = mfh * (agc.getGnh() * sc.cos() + agc.getGeh() * sc.sin());
gw = mfh * (agc.getGnw() * sc.cos() + agc.getGew() * sc.sin());
} else {
gh = 0;
gw = 0;
}
// Tropospheric path delay
return new TroposphericDelay(delays.getZh(),
delays.getZw(),
delays.getZh() * mappingFunction[0] + gh,
delays.getZw() * mappingFunction[1] + gw);
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> FieldTroposphericDelay<T> pathDelay(final FieldTrackingCoordinates<T> trackingCoordinates,
final FieldGeodeticPoint<T> point,
final FieldPressureTemperatureHumidity<T> weather,
final T[] parameters, final FieldAbsoluteDate<T> date) {
// zenith delay
final FieldTroposphericDelay<T> delays =
zenithDelayProvider.pathDelay(trackingCoordinates, point, weather, parameters, date);
// mapping function
final T[] mappingFunction =
mappingFactors(trackingCoordinates, point, weather, date);
// horizontal gradient
final FieldAzimuthalGradientCoefficients<T> agc = gProvider.getGradientCoefficients(point, date);
final T gh;
final T gw;
if (agc != null) {
// Chen and Herring gradient mapping function
final T sinE = FastMath.sin(trackingCoordinates.getElevation());
final T tanE = FastMath.tan(trackingCoordinates.getElevation());
final T mfh = sinE.multiply(tanE).add(C).reciprocal();
final FieldSinCos<T> sc = FastMath.sinCos(trackingCoordinates.getAzimuth());
gh = mfh.multiply(agc.getGnh().multiply(sc.cos()).add(agc.getGeh().multiply(sc.sin())));
gw = mfh.multiply(agc.getGnw().multiply(sc.cos()).add(agc.getGew().multiply(sc.sin())));
} else {
gh = date.getField().getZero();
gw = date.getField().getZero();
}
// Tropospheric path delay
return new FieldTroposphericDelay<>(delays.getZh(),
delays.getZw(),
delays.getZh().multiply(mappingFunction[0]).add(gh),
delays.getZw().multiply(mappingFunction[1]).add(gw));
}
/** {@inheritDoc} */
@Override
public List<ParameterDriver> getParametersDrivers() {
return Collections.emptyList();
}
/** Get provider for Vienna a<sub>h</sub> and a<sub>w</sub> coefficients.
* @return provider for Vienna a<sub>h</sub> and a<sub>w</sub> coefficients
*/
protected ViennaAProvider getAProvider() {
return aProvider;
}
/** Get day of year.
* @param date date
* @return day of year
*/
protected double getDayOfYear(final AbsoluteDate date) {
return date.getDayOfYear(utc);
}
/** Get day of year.
* @param <T> type of the field elements
* @param date date
* @return day of year
* @since 13.0
*/
protected <T extends CalculusFieldElement<T>> T getDayOfYear(final FieldAbsoluteDate<T> date) {
return date.getDayOfYear(utc);
}
}