1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17 package org.orekit.estimation.measurements.generation;
18
19 import org.hipparchus.linear.MatrixUtils;
20 import org.hipparchus.linear.RealMatrix;
21 import org.hipparchus.random.CorrelatedRandomVectorGenerator;
22 import org.hipparchus.random.GaussianRandomGenerator;
23 import org.hipparchus.random.RandomGenerator;
24 import org.hipparchus.random.Well19937a;
25 import org.hipparchus.util.FastMath;
26 import org.junit.jupiter.api.Assertions;
27 import org.junit.jupiter.api.BeforeEach;
28 import org.junit.jupiter.api.Test;
29 import org.orekit.estimation.Context;
30 import org.orekit.estimation.EstimationTestUtils;
31 import org.orekit.estimation.Force;
32 import org.orekit.estimation.measurements.EstimatedMeasurementBase;
33 import org.orekit.estimation.measurements.ObservableSatellite;
34 import org.orekit.estimation.measurements.gnss.OneWayGNSSRangeRate;
35 import org.orekit.estimation.measurements.modifiers.Bias;
36 import org.orekit.orbits.KeplerianOrbit;
37 import org.orekit.orbits.Orbit;
38 import org.orekit.orbits.OrbitType;
39 import org.orekit.orbits.PositionAngleType;
40 import org.orekit.propagation.Propagator;
41 import org.orekit.propagation.SpacecraftState;
42 import org.orekit.propagation.analytical.KeplerianPropagator;
43 import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
44 import org.orekit.propagation.events.InterSatDirectViewDetector;
45 import org.orekit.time.AbsoluteDate;
46 import org.orekit.time.FixedStepSelector;
47 import org.orekit.time.TimeScalesFactory;
48 import org.orekit.utils.PVCoordinates;
49
50 import java.util.SortedSet;
51
52 public class OneWayGNSSRangeRateBuilderTest {
53
54 private static final double SIGMA = 0.5;
55 private static final double BIAS = -0.01;
56
57 private MeasurementBuilder<OneWayGNSSRangeRate> getBuilder(final RandomGenerator random,
58 final ObservableSatellite receiver,
59 final ObservableSatellite remote) {
60 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
61 MeasurementBuilder<OneWayGNSSRangeRate> b =
62 new OneWayGNSSRangeRateBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
63 1.0e-10,
64 new GaussianRandomGenerator(random)),
65 receiver, remote,
66 SIGMA, 1.0);
67 b.addModifier(new Bias<>(new String[] { "bias" },
68 new double[] { BIAS },
69 new double[] { 1.0 },
70 new double[] { Double.NEGATIVE_INFINITY },
71 new double[] { Double.POSITIVE_INFINITY }));
72 return b;
73 }
74
75 @Test
76 public void testForward() {
77 doTest(0x066acbc9bf1074a3L, 0.0, 1.2, 2.8 * SIGMA);
78 }
79
80 @Test
81 public void testBackward() {
82 doTest(0x58ffc7ad03c2310bL, 0.0, -1.0, 2.5 * SIGMA);
83 }
84
85 private Propagator buildPropagator() {
86 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
87 }
88
89 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
90 Generator generator = new Generator();
91 generator.addPropagator(buildPropagator());
92 generator.addPropagator(buildPropagator());
93 ObservableSatellite receiver = generator.addPropagator(buildPropagator());
94 generator.addPropagator(buildPropagator());
95 final Orbit o1 = context.initialOrbit;
96
97 final Orbit o2 = new KeplerianOrbit(new PVCoordinates(o1.getPosition(),
98 o1.getPVCoordinates().getVelocity().negate()),
99 o1.getFrame(), o1.getDate(), o1.getMu());
100 ObservableSatellite remote = generator.addPropagator(new KeplerianPropagator(o2));
101 final double step = 60.0;
102
103
104
105
106
107
108 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), receiver, remote),
109 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
110 generator.getPropagator(receiver),
111 new InterSatDirectViewDetector(context.earth, new KeplerianPropagator(o2)),
112 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
113
114 final GatheringSubscriber gatherer = new GatheringSubscriber();
115 generator.addSubscriber(gatherer);
116 final double period = o1.getKeplerianPeriod();
117 AbsoluteDate t0 = o1.getDate().shiftedBy(startPeriod * period);
118 AbsoluteDate t1 = o1.getDate().shiftedBy(endPeriod * period);
119 generator.generate(t0, t1);
120 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
121
122
123 Propagator propagator1 = buildPropagator();
124 Propagator propagator2 = new KeplerianPropagator(o2);
125
126 double maxError = 0;
127 AbsoluteDate previous = null;
128 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
129 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
130 for (EstimatedMeasurementBase<?> measurement : measurements) {
131 AbsoluteDate date = measurement.getDate();
132 double[] m = measurement.getObservedValue();
133 Assertions.assertTrue(date.compareTo(tInf) >= 0);
134 Assertions.assertTrue(date.compareTo(tSup) <= 0);
135 if (previous != null) {
136 if (t0.isBefore(t1)) {
137
138 Assertions.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
139 } else {
140
141 Assertions.assertTrue(previous.durationFrom(date) >= 0.999999 * step);
142 }
143 }
144 previous = date;
145 double[] e = measurement.
146 getObservedMeasurement().
147 estimateWithoutDerivatives(new SpacecraftState[] {
148 propagator1.propagate(date),
149 propagator2.propagate(date)
150 }).
151 getEstimatedValue();
152 for (int i = 0; i < m.length; ++i) {
153 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
154 }
155 }
156 Assertions.assertEquals(0.0, maxError, tolerance);
157 }
158
159 @BeforeEach
160 public void setUp() {
161 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
162
163 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
164 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
165 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
166 }
167
168 Context context;
169 NumericalPropagatorBuilder propagatorBuilder;
170
171 }