1 /* Copyright 2002-2024 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 package org.orekit.estimation.measurements;
18
19 import org.hipparchus.util.FastMath;
20 import org.orekit.utils.ParameterDriver;
21
22 /** Class modeling a satellite that can be observed.
23 *
24 * @author Luc Maisonobe
25 * @since 9.3
26 */
27 public class ObservableSatellite {
28
29 /** Prefix for clock offset parameter driver, the propagator index will be appended to it. */
30 public static final String CLOCK_OFFSET_PREFIX = "clock-offset-satellite-";
31
32 /** Prefix for clock drift parameter driver, the propagator index will be appended to it. */
33 public static final String CLOCK_DRIFT_PREFIX = "clock-drift-satellite-";
34
35 /** Prefix for clock acceleration parameter driver, the propagator index will be appended to it.
36 * @since 12.1
37 */
38 public static final String CLOCK_ACCELERATION_PREFIX = "clock-acceleration-satellite-";
39
40 /** Clock offset scaling factor.
41 * <p>
42 * We use a power of 2 to avoid numeric noise introduction
43 * in the multiplications/divisions sequences.
44 * </p>
45 */
46 private static final double CLOCK_OFFSET_SCALE = FastMath.scalb(1.0, -10);
47
48 /** Prefix for satellite names. */
49 private static final String SAT_PREFIX = "sat-";
50
51 /** Index of the propagator related to this satellite. */
52 private final int propagatorIndex;
53
54 /** Parameter driver for satellite clock offset. */
55 private final ParameterDriver clockOffsetDriver;
56
57 /** Parameter driver for satellite clock drift. */
58 private final ParameterDriver clockDriftDriver;
59
60 /** Parameter driver for satellite clock acceleration.
61 * @since 12.1
62 */
63 private final ParameterDriver clockAccelerationDriver;
64
65 /** Simple constructor.
66 * @param propagatorIndex index of the propagator related to this satellite
67 */
68 public ObservableSatellite(final int propagatorIndex) {
69 this.propagatorIndex = propagatorIndex;
70 this.clockOffsetDriver = new ParameterDriver(CLOCK_OFFSET_PREFIX + propagatorIndex,
71 0.0, CLOCK_OFFSET_SCALE,
72 Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
73 this.clockDriftDriver = new ParameterDriver(CLOCK_DRIFT_PREFIX + propagatorIndex,
74 0.0, CLOCK_OFFSET_SCALE,
75 Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
76 this.clockAccelerationDriver = new ParameterDriver(CLOCK_ACCELERATION_PREFIX + propagatorIndex,
77 0.0, CLOCK_OFFSET_SCALE,
78 Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
79 }
80
81 /** Build a name for the satellite.
82 * <p>
83 * This is mainly useful to build the arguments for {@link
84 * org.orekit.estimation.measurements.gnss.AmbiguityCache#getAmbiguity(String,
85 * String, double)}
86 * </p>
87 * @return name for the satellite (built from the propagator index)
88 * @since 12.1
89 */
90 public String getName() {
91 return SAT_PREFIX + propagatorIndex;
92 }
93
94 /** Get the index of the propagator related to this satellite.
95 * @return index of the propagator related to this satellite
96 */
97 public int getPropagatorIndex() {
98 return propagatorIndex;
99 }
100
101 /** Get the clock offset parameter driver.
102 * <p>
103 * The offset value is defined as the value in seconds that must be <em>subtracted</em> from
104 * the satellite clock reading of time to compute the real physical date. The offset
105 * is therefore negative if the satellite clock is slow and positive if it is fast.
106 * </p>
107 * @return clock offset parameter driver
108 */
109 public ParameterDriver getClockOffsetDriver() {
110 return clockOffsetDriver;
111 }
112
113 /** Get the clock drift parameter driver.
114 * <p>
115 * The drift is negative if the satellite clock is slowing down and positive if it is speeding up.
116 * </p>
117 * @return clock drift parameter driver
118 * @since 10.3
119 */
120 public ParameterDriver getClockDriftDriver() {
121 return clockDriftDriver;
122 }
123
124 /** Get the clock acceleration parameter driver.
125 * @return clock acceleration parameter driver
126 * @since 12.1
127 */
128 public ParameterDriver getClockAccelerationDriver() {
129 return clockAccelerationDriver;
130 }
131
132 /** Get a quadratic clock model valid at some date.
133 * @return quadratic clock model
134 * @since 12.1
135 */
136 public QuadraticClockModel getQuadraticClockModel() {
137 return new QuadraticClockModel(clockOffsetDriver,
138 clockDriftDriver,
139 clockAccelerationDriver);
140 }
141
142 /** {@inheritDoc}
143 * @since 12.0
144 */
145 @Override
146 public boolean equals(final Object other) {
147 if (other instanceof ObservableSatellite) {
148 return propagatorIndex == ((ObservableSatellite) other).propagatorIndex;
149 } else {
150 return false;
151
152 }
153 }
154
155 /** {@inheritDoc}
156 * @since 12.0
157 */
158 @Override
159 public int hashCode() {
160 return propagatorIndex;
161 }
162
163 }