TroposphericModel.java
/* Copyright 2011-2012 Space Applications Services
* Licensed to CS Communication & Systèmes (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.models.earth;
import java.util.Collections;
import java.util.List;
import org.hipparchus.Field;
import org.hipparchus.RealFieldElement;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.MathArrays;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.utils.ParameterDriver;
/** Defines a tropospheric model, used to calculate the path delay imposed to
* electro-magnetic signals between an orbital satellite and a ground station.
* <p>
* Models that implement this interface don't split the delay into hydrostatic
* and non-hydrostatic part.
* </p>
* @author Thomas Neidhart
* @since 7.1
*/
public interface TroposphericModel extends DiscreteTroposphericModel {
/** Calculates the tropospheric path delay for the signal path from a ground
* 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
* @return the path delay due to the troposphere in m
*/
double pathDelay(double elevation, double height);
/** Calculates the tropospheric path delay for the signal path from a ground
* station to a satellite.
* <p>
* It is discourage to use this method. It has been developed to respect the
* current architecture of the tropospheric models.
* </p>
* @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
* @return the path delay due to the troposphere in m
*/
default <T extends RealFieldElement<T>> T pathDelay(T elevation, T height) {
final T zero = height.getField().getZero();
return zero.add(pathDelay(elevation.getReal(), height.getReal()));
}
/** Calculates the tropospheric path delay for the signal path from a ground
* 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 date current date
* @return the path delay due to the troposphere in m
*/
default double pathDelay(double elevation, double height, double[] parameters, AbsoluteDate date) {
return pathDelay(elevation, height);
}
/** 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 date current date
* @return the path delay due to the troposphere in m
*/
default <T extends RealFieldElement<T>> T pathDelay(T elevation, T height, T[] parameters, FieldAbsoluteDate<T> date) {
return pathDelay(elevation, height);
}
/** This method allows the computation of the zenith hydrostatic and
* zenith wet delay. The resulting element is an array having the following form:
* <ul>
* <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 date current date
* @return a two components array containing the zenith hydrostatic and wet delays.
*/
default double[] computeZenithDelay(double height, double[] parameters, AbsoluteDate date) {
return new double[] {
pathDelay(0.5 * FastMath.PI, height),
0
};
}
/** This method allows the computation of the zenith hydrostatic and
* zenith wet delay. The resulting element is an array having the following form:
* <ul>
* <li>double[0] = D<sub>hz</sub> → zenith hydrostatic delay
* <li>double[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 date current date
* @return a two components array containing the zenith hydrostatic and wet delays.
*/
default <T extends RealFieldElement<T>> T[] computeZenithDelay(T height, T[] parameters, FieldAbsoluteDate<T> date) {
final Field<T> field = height.getField();
final T zero = field.getZero();
final T[] delay = MathArrays.buildArray(field, 2);
delay[0] = pathDelay(zero.add(0.5 * FastMath.PI), height);
delay[1] = zero;
return delay;
}
/** This method allows the computation of the hydrostatic and
* wet mapping functions. The resulting element is an array having the following form:
* <ul>
* <li>double[0] = m<sub>h</sub>(e) → hydrostatic mapping function
* <li>double[1] = m<sub>w</sub>(e) → wet mapping function
* </ul>
* @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 date current date
* @return a two components array containing the hydrostatic and wet mapping functions.
*/
default double[] mappingFactors(double elevation, double height, double[] parameters, AbsoluteDate date) {
return new double[] {
1.0,
1.0
};
}
/** This method allows the computation of the hydrostatic and
* wet mapping functions. The resulting element is an array having the following form:
* <ul>
* <li>double[0] = m<sub>h</sub>(e) → hydrostatic mapping function
* <li>double[1] = m<sub>w</sub>(e) → wet mapping function
* </ul>
* @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 date current date
* @param <T> type of the elements
* @return a two components array containing the hydrostatic and wet mapping functions.
*/
default <T extends RealFieldElement<T>> T[] mappingFactors(T elevation, T height,
T[] parameters, FieldAbsoluteDate<T> date) {
final Field<T> field = date.getField();
final T one = field.getOne();
final T[] factors = MathArrays.buildArray(field, 2);
factors[0] = one;
factors[1] = one;
return factors;
}
/** Get the drivers for tropospheric model parameters.
* @return drivers for tropospheric model parameters
*/
default List<ParameterDriver> getParametersDrivers() {
return Collections.emptyList();
}
}