1   /* Copyright 2011-2012 Space Applications Services
2    * Licensed to CS Communication & Systèmes (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.models.earth;
18  
19  import java.io.Serializable;
20  
21  /** Defines a tropospheric model, used to calculate the path delay imposed to
22   * electro-magnetic signals between an orbital satellite and a ground station.
23   * @author Thomas Neidhart
24   */
25  public interface TroposphericDelayModel extends Serializable {
26  
27      /** Calculates the tropospheric path delay for the signal path from a ground
28       * station to a satellite.
29       *
30       * @param elevation the elevation of the satellite in degrees
31       * @param height the height of the station in m above sea level
32       * @return the path delay due to the troposphere in m
33       */
34      double calculatePathDelay(final double elevation, final double height);
35  
36      /** Calculates the tropospheric signal delay for the signal path from a
37       * ground station to a satellite. This method exists only for convenience
38       * reasons and returns the same as
39       *
40       * <pre>
41       *   {@link SaastamoinenModel#calculatePathDelay(double, double)}/{@link org.orekit.utils.Constants#SPEED_OF_LIGHT}
42       * </pre>
43       *
44       * @param elevation the elevation of the satellite in degrees
45       * @param height the height of the station in m above sea level
46       * @return the signal delay due to the troposphere in s
47       */
48      double calculateSignalDelay(final double elevation, final double height);
49  
50  }