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17 package org.orekit.estimation.measurements.generation;
18
19 import java.util.SortedSet;
20
21 import org.hipparchus.linear.MatrixUtils;
22 import org.hipparchus.linear.RealMatrix;
23 import org.hipparchus.random.CorrelatedRandomVectorGenerator;
24 import org.hipparchus.random.GaussianRandomGenerator;
25 import org.hipparchus.random.RandomGenerator;
26 import org.hipparchus.random.Well19937a;
27 import org.hipparchus.util.FastMath;
28 import org.junit.jupiter.api.Assertions;
29 import org.junit.jupiter.api.BeforeEach;
30 import org.junit.jupiter.api.Test;
31 import org.orekit.estimation.Context;
32 import org.orekit.estimation.EstimationTestUtils;
33 import org.orekit.estimation.Force;
34 import org.orekit.estimation.measurements.EstimatedMeasurementBase;
35 import org.orekit.estimation.measurements.ObservableSatellite;
36 import org.orekit.estimation.measurements.gnss.OneWayGNSSRange;
37 import org.orekit.estimation.measurements.modifiers.Bias;
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 public class OneWayGNSSRangeBuilderTest {
53
54 private static final double SIGMA = 0.5;
55 private static final double BIAS = -0.01;
56
57 private MeasurementBuilder<OneWayGNSSRange> getBuilder(final RandomGenerator random,
58 final ObservableSatellite receiver,
59 final ObservableSatellite remote) {
60 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
61 remote.getClockOffsetDriver().setReferenceDate(AbsoluteDate.ARBITRARY_EPOCH);
62 remote.getClockOffsetDriver().setValue(1.0e-16);
63 remote.getClockDriftDriver().setReferenceDate(AbsoluteDate.ARBITRARY_EPOCH);
64 remote.getClockDriftDriver().setValue(0);
65 remote.getClockAccelerationDriver().setReferenceDate(AbsoluteDate.ARBITRARY_EPOCH);
66 remote.getClockAccelerationDriver().setValue(0);
67 MeasurementBuilder<OneWayGNSSRange> b =
68 new OneWayGNSSRangeBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
69 1.0e-10,
70 new GaussianRandomGenerator(random)),
71 receiver, remote,
72 SIGMA, 1.0);
73 b.addModifier(new Bias<>(new String[] { "bias" },
74 new double[] { BIAS },
75 new double[] { 1.0 },
76 new double[] { Double.NEGATIVE_INFINITY },
77 new double[] { Double.POSITIVE_INFINITY }));
78 return b;
79 }
80
81 @Test
82 public void testForward() {
83 doTest(0x6f44484882311d49L, 0.0, 1.2, 2.9 * SIGMA);
84 }
85
86 @Test
87 public void testBackward() {
88 doTest(0x486b1353daa9f73eL, 0.0, -1.0, 3.6 * SIGMA);
89 }
90
91 private Propagator buildPropagator() {
92 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
93 }
94
95 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
96 Generator generator = new Generator();
97 generator.addPropagator(buildPropagator());
98 generator.addPropagator(buildPropagator());
99 ObservableSatellite receiver = generator.addPropagator(buildPropagator());
100 generator.addPropagator(buildPropagator());
101 final Orbit o1 = context.initialOrbit;
102
103 final Orbit o2 = new KeplerianOrbit(new PVCoordinates(o1.getPosition(),
104 o1.getPVCoordinates().getVelocity().negate()),
105 o1.getFrame(), o1.getDate(), o1.getMu());
106 ObservableSatellite remote = generator.addPropagator(new KeplerianPropagator(o2));
107 final double step = 60.0;
108
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111
112
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114 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), receiver, remote),
115 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
116 generator.getPropagator(receiver),
117 new InterSatDirectViewDetector(context.earth, new KeplerianPropagator(o2)),
118 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
119
120 final GatheringSubscriber gatherer = new GatheringSubscriber();
121 generator.addSubscriber(gatherer);
122 final double period = o1.getKeplerianPeriod();
123 AbsoluteDate t0 = o1.getDate().shiftedBy(startPeriod * period);
124 AbsoluteDate t1 = o1.getDate().shiftedBy(endPeriod * period);
125 generator.generate(t0, t1);
126 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
127
128
129 Propagator propagator1 = buildPropagator();
130 Propagator propagator2 = new KeplerianPropagator(o2);
131
132 double maxError = 0;
133 AbsoluteDate previous = null;
134 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
135 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
136 for (EstimatedMeasurementBase<?> measurement : measurements) {
137 AbsoluteDate date = measurement.getDate();
138 double[] m = measurement.getObservedValue();
139 Assertions.assertTrue(date.compareTo(tInf) >= 0);
140 Assertions.assertTrue(date.compareTo(tSup) <= 0);
141 if (previous != null) {
142 if (t0.isBefore(t1)) {
143
144 Assertions.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
145 } else {
146
147 Assertions.assertTrue(previous.durationFrom(date) >= 0.999999 * step);
148 }
149 }
150 previous = date;
151 double[] e = measurement.
152 getObservedMeasurement().
153 estimateWithoutDerivatives(new SpacecraftState[] {
154 propagator1.propagate(date),
155 propagator2.propagate(date)
156 }).
157 getEstimatedValue();
158 for (int i = 0; i < m.length; ++i) {
159 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
160 }
161 }
162 Assertions.assertEquals(0.0, maxError, tolerance);
163 }
164
165 @BeforeEach
166 public void setUp() {
167 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
168
169 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
170 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
171 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
172 }
173
174 Context context;
175 NumericalPropagatorBuilder propagatorBuilder;
176
177 }