1 /* Copyright 2022-2025 Thales Alenia Space
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.gnss.rflink.gps;
18
19 import org.hipparchus.util.FastMath;
20 import org.orekit.gnss.metric.parser.Units;
21
22 /**
23 * Container for sub-frames 5, page 1-24.
24 * <p>
25 * Table 20-1, sheet 4 and table 40-1, sheet 4 in
26 * <a href="https://navcen.uscg.gov/sites/default/files/pdf/gps/IS-GPS-200N.pdf">NAVSTAR
27 * GPS Space Segment/Navigation User Segment Interface</a>, IS-GPS-200N, 22 Aug 2022
28 * </p>
29 * @author Luc Maisonobe
30 * @since 12.0
31 */
32 public class SubFrameAlmanac extends SubFrame45 {
33
34 /** Index of e field. */
35 private static final int E = 9;
36
37 /** Index of TOA field. */
38 private static final int TOA = 10;
39
40 /** Index of δi field. */
41 private static final int DELTA_I = 11;
42
43 /** Index of dot(Ω) field. */
44 private static final int OMEGA_DOT = 12;
45
46 /** Index of SV health field. */
47 private static final int SV_HEALTH = 13;
48
49 /** Index of √a field. */
50 private static final int SQRT_A = 14;
51
52 /** Index of Ω₀ field. */
53 private static final int UPPERCASE_OMEGA_0 = 15;
54
55 /** Index of ω field. */
56 private static final int LOWERCASE_OMEGA = 16;
57
58 /** Index of M₀ field. */
59 private static final int M0 = 17;
60
61 /** Index of AF0 field. */
62 private static final int AF0 = 18;
63
64 /** Index of AF1 field. */
65 private static final int AF1 = 19;
66
67 /** Simple constructor.
68 * @param words raw words
69 */
70 SubFrameAlmanac(final int[] words) {
71
72 // create raw container
73 super(words, AF1 + 1);
74
75 // populate container
76 setField(E, 3, 6, 16, words);
77 setField(TOA, 4, 22, 8, words);
78 setField(DELTA_I, 4, 6, 16, words);
79 setField(OMEGA_DOT, 5, 14, 16, words);
80 setField(SV_HEALTH, 5, 6, 8, words);
81 setField(SQRT_A, 6, 6, 24, words);
82 setField(UPPERCASE_OMEGA_0, 7, 6, 24, words);
83 setField(LOWERCASE_OMEGA, 8, 6, 24, words);
84 setField(M0, 9, 6, 24, words);
85 setField(AF0, 10, 22, 8, 10, 8, 3, words);
86 setField(AF1, 10, 11, 11, words);
87
88 }
89
90 /** Get the PRN code phase of the SV.
91 * @return PRN code phase
92 */
93 public int getPRN() {
94 // sub-frames that contain almanacs use the SV-ID for the PRN
95 return getSvId();
96 }
97
98 /** Get eccentricity.
99 * @return eccentricity
100 */
101 public double getE() {
102 return FastMath.scalb((double) getField(E), -21);
103 }
104
105 /** Get Time Of Almanac.
106 * @return Time Of Almanac (seconds)
107 */
108 public int getToaA() {
109 return getField(TOA) << 12;
110 }
111
112 /** Get Δi.
113 * @return Δi (rad)
114 */
115 public double getDeltai() {
116 return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(DELTA_I), -19));
117 }
118
119 /** Get dot(Ω).
120 * @return dot(Ω) (rad/s)
121 */
122 public double getOmegaDot() {
123 return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(OMEGA_DOT), -38));
124 }
125
126 /** Get SV health.
127 * @return SV health
128 */
129 public int getSvHealth() {
130 return getField(SV_HEALTH);
131 }
132
133 /** Get √a.
134 * @return d√a (√m)
135 */
136 public double getSqrtA() {
137 return FastMath.scalb((double) getField(SQRT_A), -11);
138 }
139
140 /** Get Ω₀.
141 * @return Ω₀ (rad)
142 */
143 public double getUppercaseOmega0() {
144 return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(UPPERCASE_OMEGA_0), -23));
145 }
146
147 /** Get ω.
148 * @return ω(rad)
149 */
150 public double getLowercaseOmega() {
151 return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(LOWERCASE_OMEGA), -23));
152 }
153
154 /** Get M₀.
155 * @return M₀ (rad)
156 */
157 public double getM0() {
158 return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(M0), -23));
159 }
160
161 /** Get af₀.
162 * @return af₀ (second)
163 */
164 public double getAF0() {
165 return FastMath.scalb((double) getField(AF0), -20);
166 }
167
168 /** Get af₁.
169 * @return af₁ (second/second)
170 */
171 public double getAF1() {
172 return FastMath.scalb((double) getField(AF1), -38);
173 }
174
175 }