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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.AmbiguityCache;
35 import org.orekit.estimation.measurements.gnss.InterSatellitesPhase;
36 import org.orekit.estimation.measurements.modifiers.Bias;
37 import org.orekit.gnss.PredefinedGnssSignal;
38 import org.orekit.orbits.KeplerianOrbit;
39 import org.orekit.orbits.Orbit;
40 import org.orekit.orbits.OrbitType;
41 import org.orekit.orbits.PositionAngleType;
42 import org.orekit.propagation.Propagator;
43 import org.orekit.propagation.SpacecraftState;
44 import org.orekit.propagation.analytical.KeplerianPropagator;
45 import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
46 import org.orekit.propagation.events.InterSatDirectViewDetector;
47 import org.orekit.time.AbsoluteDate;
48 import org.orekit.time.FixedStepSelector;
49 import org.orekit.time.TimeScalesFactory;
50 import org.orekit.utils.PVCoordinates;
51
52 import java.util.SortedSet;
53
54 public class InterSatellitesPhaseBuilderTest {
55
56 private static final double SIGMA = 0.5;
57 private static final double BIAS = -0.01;
58 private static final double WAVELENGTH = PredefinedGnssSignal.G01.getWavelength();
59
60 private MeasurementBuilder<InterSatellitesPhase> getBuilder(final RandomGenerator random,
61 final ObservableSatellite receiver,
62 final ObservableSatellite remote) {
63 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
64 MeasurementBuilder<InterSatellitesPhase> isrb =
65 new InterSatellitesPhaseBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
66 1.0e-10,
67 new GaussianRandomGenerator(random)),
68 receiver, remote, WAVELENGTH, SIGMA, 1.0,
69 new AmbiguityCache());
70 isrb.addModifier(new Bias<>(new String[] { "bias" },
71 new double[] { BIAS },
72 new double[] { 1.0 },
73 new double[] { Double.NEGATIVE_INFINITY },
74 new double[] { Double.POSITIVE_INFINITY }));
75 return isrb;
76 }
77
78 @Test
79 public void testForward() {
80 doTest(0xc82a56322345dc25L, 0.0, 1.2, 2.8 * SIGMA);
81 }
82
83 @Test
84 public void testBackward() {
85 doTest(0x95c10149c4891232L, 0.0, -1.0, 2.6 * SIGMA);
86 }
87
88 private Propagator buildPropagator() {
89 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
90 }
91
92 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
93 Generator generator = new Generator();
94 generator.addPropagator(buildPropagator());
95 generator.addPropagator(buildPropagator());
96 ObservableSatellite receiver = generator.addPropagator(buildPropagator());
97 generator.addPropagator(buildPropagator());
98 final Orbit o1 = context.initialOrbit;
99
100 final Orbit o2 = new KeplerianOrbit(new PVCoordinates(o1.getPosition(),
101 o1.getPVCoordinates().getVelocity().negate()),
102 o1.getFrame(), o1.getDate(), o1.getMu());
103 ObservableSatellite remote = generator.addPropagator(new KeplerianPropagator(o2));
104 final double step = 60.0;
105
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111 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), receiver, remote),
112 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
113 generator.getPropagator(receiver),
114 new InterSatDirectViewDetector(context.earth, new KeplerianPropagator(o2)),
115 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
116
117 final GatheringSubscriber gatherer = new GatheringSubscriber();
118 generator.addSubscriber(gatherer);
119 final double period = o1.getKeplerianPeriod();
120 AbsoluteDate t0 = o1.getDate().shiftedBy(startPeriod * period);
121 AbsoluteDate t1 = o1.getDate().shiftedBy(endPeriod * period);
122 generator.generate(t0, t1);
123 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
124
125
126 Propagator propagator1 = buildPropagator();
127 Propagator propagator2 = new KeplerianPropagator(o2);
128
129 double maxError = 0;
130 AbsoluteDate previous = null;
131 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
132 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
133 for (EstimatedMeasurementBase<?> measurement : measurements) {
134 AbsoluteDate date = measurement.getDate();
135 double[] m = measurement.getObservedValue();
136 Assertions.assertTrue(date.compareTo(tInf) >= 0);
137 Assertions.assertTrue(date.compareTo(tSup) <= 0);
138 if (previous != null) {
139 if (t0.isBefore(t1)) {
140
141 Assertions.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
142 } else {
143
144 Assertions.assertTrue(previous.durationFrom(date) >= 0.999999 * step);
145 }
146 }
147 previous = date;
148 double[] e = measurement.
149 getObservedMeasurement().
150 estimateWithoutDerivatives(new SpacecraftState[] {
151 propagator1.propagate(date),
152 propagator2.propagate(date)
153 }).
154 getEstimatedValue();
155 for (int i = 0; i < m.length; ++i) {
156 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
157 }
158 }
159 Assertions.assertEquals(0.0, maxError, tolerance);
160 }
161
162 @BeforeEach
163 public void setUp() {
164 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
165
166 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
167 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
168 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
169 }
170
171 Context context;
172 NumericalPropagatorBuilder propagatorBuilder;
173
174 }