1   /* Copyright 2002-2025 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.gnss.ObservationType;
25  import org.orekit.time.AbsoluteDate;
26  import org.orekit.utils.TimeSpanMap;
27  
28  /** Container for differential signal bias for a single link endpoint
29   * (either emitter or receiver).
30   * <p>
31   * This class is made to handle both station and satellite DSB data.
32   * Bias values are stored in TimeSpanMaps associated with a given pair
33   * of observation types. Those TimeSpanMaps are stored in a Map, which
34   * associate a pair of observation types to a TimeSpanMap of double values.
35   * </p>
36   * @author Louis Aucouturier
37   * @since 12.0
38   */
39  public class DifferentialSignalBias {
40  
41      /** Set of observation type pairs available for the satellite. */
42      private final HashSet<Pair<ObservationType, ObservationType>> observationSets;
43  
44      /** Set of biases, identifiable by observation type pairs,
45       * each containing the corresponding TimeSpanMap of biases (DSB).
46       */
47      private final HashMap<Pair<ObservationType, ObservationType>, TimeSpanMap<Double>> biases;
48  
49      /** Simple constructor.
50       */
51      public DifferentialSignalBias() {
52          this.observationSets = new HashSet<>();
53          this.biases          = new HashMap<>();
54      }
55  
56      /** Add a bias.
57       * @param obs1 first observation used for the DSB computation
58       * @param obs2 second observation used for the DSB computation
59       * @param spanBegin beginning of the validity span for this bias value
60       * @param spanEnd end of the validity span for this bias value
61       * @param biasValue DSB bias value (meters for code and cycle for phase)
62       */
63      public void addBias(final ObservationType obs1, final ObservationType obs2,
64                          final AbsoluteDate spanBegin, final AbsoluteDate spanEnd,
65                          final double biasValue) {
66  
67          // Setting a pair of observation type.
68          final Pair<ObservationType, ObservationType> observationPair = new Pair<>(obs1, obs2);
69  
70          // If not present add a new bias to the map, identified by the Observation Pair.
71          // Then add the bias value and validity period.
72          if (observationSets.add(observationPair)) {
73              biases.put(observationPair, new TimeSpanMap<>(null));
74          }
75  
76          biases.get(observationPair).addValidBetween(biasValue, spanBegin, spanEnd);
77  
78      }
79  
80      /** Get the value of the Differential Signal Bias for a given observation pair at a given date.
81       * @param obs1 first observation type
82       * @param obs2 second observation type
83       * @param date date at which to obtain the DSB
84       * @return the value of the DSB (meters for code and cycle for phase)
85       */
86      public double getBias(final ObservationType obs1, final ObservationType obs2, final AbsoluteDate date) {
87          return getTimeSpanMap(obs1, obs2).get(date);
88      }
89  
90      /** Get all available observation type pairs for the satellite.
91       * @return observation type pairs obtained.
92       */
93      public HashSet<Pair<ObservationType, ObservationType>> getAvailableObservationPairs() {
94          return observationSets;
95      }
96  
97      /** Get the minimum valid date for a given observation pair.
98       * @param obs1 first observation type
99       * @param obs2 second observation type
100      * @return minimum valid date for the observation pair
101      */
102     public AbsoluteDate getMinimumValidDateForObservationPair(final ObservationType obs1, final ObservationType obs2) {
103         return getTimeSpanMap(obs1, obs2).getFirstTransition().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 ObservationType obs1, final ObservationType obs2) {
112         return getTimeSpanMap(obs1, obs2).getLastTransition().getDate();
113     }
114 
115     /** Get the TimeSpanMap object for a given observation type pair,
116      * for further operation on the object directly.
117      *
118      * @param obs1 first observation type
119      * @param obs2 second observation type
120      * @return the time span map for a given observation type pair
121      */
122     private TimeSpanMap<Double> getTimeSpanMap(final ObservationType obs1, final ObservationType obs2) {
123         return biases.get(new Pair<>(obs1, obs2));
124     }
125 
126 }