1   /* Copyright 2002-2026 CS GROUP
2    * Licensed to CS GROUP (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  
18  package org.orekit.files.sinex;
19  
20  import java.util.HashMap;
21  import java.util.HashSet;
22  
23  import org.hipparchus.util.Pair;
24  import org.orekit.time.AbsoluteDate;
25  import org.orekit.utils.TimeSpanMap;
26  
27  /** Container for differential signal bias for a single link endpoint
28   * (either emitter or receiver).
29   * <p>
30   * This class is made to handle both station and satellite DSB data.
31   * Bias values are stored in TimeSpanMaps associated with a given pair
32   * of observation types. Those TimeSpanMaps are stored in a Map, which
33   * associate a pair of observation types to a TimeSpanMap of double values.
34   * </p>
35   * @author Louis Aucouturier
36   * @since 12.0
37   */
38  public class DifferentialSignalBias {
39  
40      /** Set of observation type pairs available for the satellite. */
41      private final HashSet<Pair<String, String>> observationSets;
42  
43      /** Set of biases, identifiable by observation type pairs,
44       * each containing the corresponding TimeSpanMap of biases (DSB).
45       */
46      private final HashMap<Pair<String, String>, TimeSpanMap<Double>> biases;
47  
48      /** Simple constructor.
49       */
50      public DifferentialSignalBias() {
51          this.observationSets = new HashSet<>();
52          this.biases          = new HashMap<>();
53      }
54  
55      /** Add a bias.
56       * @param obs1 first observation used for the DSB computation
57       * @param obs2 second observation used for the DSB computation
58       * @param spanBegin beginning of the validity span for this bias value
59       * @param spanEnd end of the validity span for this bias value
60       * @param biasValue DSB bias value (meters for code and cycle for phase)
61       */
62      public void addBias(final String obs1, final String obs2,
63                          final AbsoluteDate spanBegin, final AbsoluteDate spanEnd,
64                          final double biasValue) {
65  
66          // Setting a pair of observation type.
67          final Pair<String, String> observationPair = new Pair<>(obs1, obs2);
68  
69          // If not present add a new bias to the map, identified by the Observation Pair.
70          // Then add the bias value and validity period.
71          if (observationSets.add(observationPair)) {
72              biases.put(observationPair, new TimeSpanMap<>(null));
73          }
74  
75          biases.get(observationPair).addValidBetween(biasValue, spanBegin, spanEnd);
76  
77      }
78  
79      /** Get the value of the Differential Signal Bias for a given observation pair at a given date.
80       * @param obs1 first observation type
81       * @param obs2 second observation type
82       * @param date date at which to obtain the DSB
83       * @return the value of the DSB (meters for code and cycle for phase)
84       */
85      public double getBias(final String obs1, final String obs2, final AbsoluteDate date) {
86          return getTimeSpanMap(obs1, obs2).get(date);
87      }
88  
89      /** Get all available observation type pairs for the satellite.
90       * @return observation type pairs obtained.
91       */
92      public HashSet<Pair<String, String>> getAvailableObservationPairs() {
93          return observationSets;
94      }
95  
96      /** Get the minimum valid date for a given observation pair.
97       * @param obs1 first observation type
98       * @param obs2 second observation type
99       * @return minimum valid date for the observation pair
100      */
101     public AbsoluteDate getMinimumValidDateForObservationPair(final String obs1, final String obs2) {
102         final TimeSpanMap.Transition<Double> transition = getTimeSpanMap(obs1, obs2).getFirstTransition();
103         return transition == null ? AbsoluteDate.PAST_INFINITY : transition.getDate();
104     }
105 
106     /** Get the maximum valid date for a given observation pair.
107      * @param obs1 first observation type
108      * @param obs2 second observation type
109      * @return maximum valid date for the observation pair
110      */
111     public AbsoluteDate getMaximumValidDateForObservationPair(final String obs1, final String obs2) {
112         final TimeSpanMap.Transition<Double> transition = getTimeSpanMap(obs1, obs2).getLastTransition();
113         return transition == null ? AbsoluteDate.FUTURE_INFINITY : transition.getDate();
114     }
115 
116     /** Get the TimeSpanMap object for a given observation type pair,
117      * for further operation on the object directly.
118      *
119      * @param obs1 first observation type
120      * @param obs2 second observation type
121      * @return the time span map for a given observation type pair
122      */
123     public TimeSpanMap<Double> getTimeSpanMap(final String obs1, final String obs2) {
124         return biases.get(new Pair<>(obs1, obs2));
125     }
126 
127 }