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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.InterSatellitesOneWayRangeRate;
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 InterSatellitesOneWayRangeRateBuilderTest {
53
54 private static final double SIGMA = 0.5;
55 private static final double BIAS = -0.01;
56
57 private MeasurementBuilder<InterSatellitesOneWayRangeRate> getBuilder(final RandomGenerator random,
58 final ObservableSatellite receiver,
59 final ObservableSatellite remote) {
60 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
61 MeasurementBuilder<InterSatellitesOneWayRangeRate> isrb =
62 new InterSatellitesOneWayRangeRateBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
63 1.0e-10,
64 new GaussianRandomGenerator(random)),
65 receiver, remote, SIGMA, 1.0);
66 isrb.addModifier(new Bias<>(new String[] { "bias" },
67 new double[] { BIAS },
68 new double[] { 1.0 },
69 new double[] { Double.NEGATIVE_INFINITY },
70 new double[] { Double.POSITIVE_INFINITY }));
71 return isrb;
72 }
73
74 @Test
75 public void testForward() {
76 doTest(0x5006ca3f1e03ea93L, 0.0, 1.2, 2.4 * SIGMA);
77 }
78
79 @Test
80 public void testBackward() {
81 doTest(0xd7643ffbaff67906L, 0.0, -1.0, 3.0 * SIGMA);
82 }
83
84 private Propagator buildPropagator() {
85 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
86 }
87
88 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
89 Generator generator = new Generator();
90 generator.addPropagator(buildPropagator());
91 generator.addPropagator(buildPropagator());
92 ObservableSatellite receiver = generator.addPropagator(buildPropagator());
93 generator.addPropagator(buildPropagator());
94 final Orbit o1 = context.initialOrbit;
95
96 final Orbit o2 = new KeplerianOrbit(new PVCoordinates(o1.getPosition(),
97 o1.getPVCoordinates().getVelocity().negate()),
98 o1.getFrame(), o1.getDate(), o1.getMu());
99 ObservableSatellite remote = generator.addPropagator(new KeplerianPropagator(o2));
100 final double step = 60.0;
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107 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), receiver, remote),
108 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
109 generator.getPropagator(receiver),
110 new InterSatDirectViewDetector(context.earth, new KeplerianPropagator(o2)),
111 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
112
113 final GatheringSubscriber gatherer = new GatheringSubscriber();
114 generator.addSubscriber(gatherer);
115 final double period = o1.getKeplerianPeriod();
116 AbsoluteDate t0 = o1.getDate().shiftedBy(startPeriod * period);
117 AbsoluteDate t1 = o1.getDate().shiftedBy(endPeriod * period);
118 generator.generate(t0, t1);
119 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
120
121
122 Propagator propagator1 = buildPropagator();
123 Propagator propagator2 = new KeplerianPropagator(o2);
124
125 double maxError = 0;
126 AbsoluteDate previous = null;
127 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
128 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
129 for (EstimatedMeasurementBase<?> measurement : measurements) {
130 AbsoluteDate date = measurement.getDate();
131 double[] m = measurement.getObservedValue();
132 Assertions.assertTrue(date.compareTo(tInf) >= 0);
133 Assertions.assertTrue(date.compareTo(tSup) <= 0);
134 if (previous != null) {
135 if (t0.isBefore(t1)) {
136
137 Assertions.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
138 } else {
139
140 Assertions.assertTrue(previous.durationFrom(date) >= 0.999999 * step);
141 }
142 }
143 previous = date;
144 double[] e = measurement.
145 getObservedMeasurement().
146 estimateWithoutDerivatives(new SpacecraftState[] {
147 propagator1.propagate(date),
148 propagator2.propagate(date)
149 }).
150 getEstimatedValue();
151 for (int i = 0; i < m.length; ++i) {
152 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
153 }
154 }
155 Assertions.assertEquals(0.0, maxError, tolerance);
156 }
157
158 @BeforeEach
159 public void setUp() {
160 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
161
162 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
163 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
164 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
165 }
166
167 Context context;
168 NumericalPropagatorBuilder propagatorBuilder;
169
170 }