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 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.FDOA;
36 import org.orekit.estimation.measurements.GroundStation;
37 import org.orekit.estimation.measurements.ObservableSatellite;
38 import org.orekit.estimation.measurements.modifiers.Bias;
39 import org.orekit.orbits.OrbitType;
40 import org.orekit.orbits.PositionAngleType;
41 import org.orekit.propagation.Propagator;
42 import org.orekit.propagation.SpacecraftState;
43 import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
44 import org.orekit.propagation.events.BooleanDetector;
45 import org.orekit.propagation.events.ElevationDetector;
46 import org.orekit.time.AbsoluteDate;
47 import org.orekit.time.FixedStepSelector;
48 import org.orekit.time.TimeScalesFactory;
49
50 public class FDOABuilderTest {
51
52
53 private static final double CENTRE_FREQUENCY = 2.3e9;
54
55 private static final double SIGMA = 0.01;
56 private static final double BIAS = 1.e-8;
57
58 private MeasurementBuilder<FDOA> getBuilder(final RandomGenerator random,
59 final GroundStation primary,
60 final GroundStation secondary,
61 final ObservableSatellite satellite) {
62 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
63 MeasurementBuilder<FDOA> fdoab =
64 new FDOABuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
65 1.0e-10,
66 new GaussianRandomGenerator(random)),
67 primary, secondary, CENTRE_FREQUENCY, SIGMA, 1.0, satellite);
68 fdoab.addModifier(new Bias<>(new String[] { "bias" },
69 new double[] { BIAS },
70 new double[] { 1.0 },
71 new double[] { Double.NEGATIVE_INFINITY },
72 new double[] { Double.POSITIVE_INFINITY }));
73 return fdoab;
74 }
75
76 @Test
77 public void testForward() {
78 doTest(0xf50c0ce7c8c1dab2L, 0.0, 1.2, 3.2 * SIGMA);
79 }
80
81 @Test
82 public void testBackward() {
83 doTest(0x453a681440d01832L, 0.0, -1.2, 2.9 * SIGMA);
84 }
85
86 private Propagator buildPropagator() {
87 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
88 }
89
90 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
91 Generator generator = new Generator();
92 final double step = 60.0;
93 final GroundStation emitter = context.FDOAstations.getFirst();
94 final GroundStation receiver = context.FDOAstations.getSecond();
95 generator.addPropagator(buildPropagator());
96 generator.addPropagator(buildPropagator());
97 ObservableSatellite satellite = generator.addPropagator(buildPropagator());
98 generator.addPropagator(buildPropagator());
99 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), emitter, receiver, satellite),
100 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
101 generator.getPropagator(satellite),
102 BooleanDetector.andCombine(EstimationTestUtils.getElevationDetector(emitter.getBaseFrame(),
103 FastMath.toRadians(5.0)),
104 EstimationTestUtils.getElevationDetector(receiver.getBaseFrame(),
105 FastMath.toRadians(5.0))),
106 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
107 final GatheringSubscriber gatherer = new GatheringSubscriber();
108 generator.addSubscriber(gatherer);
109 final double period = context.initialOrbit.getKeplerianPeriod();
110 AbsoluteDate t0 = context.initialOrbit.getDate().shiftedBy(startPeriod * period);
111 AbsoluteDate t1 = context.initialOrbit.getDate().shiftedBy(endPeriod * period);
112 generator.generate(t0, t1);
113 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
114 Propagator propagator = buildPropagator();
115 double maxError = 0;
116 AbsoluteDate previous = null;
117 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
118 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
119 for (EstimatedMeasurementBase<?> measurement : measurements) {
120 AbsoluteDate date = measurement.getDate();
121 double[] m = measurement.getObservedValue();
122 Assertions.assertTrue(date.compareTo(tInf) >= 0);
123 Assertions.assertTrue(date.compareTo(tSup) <= 0);
124 if (previous != null) {
125 if (t0.isBefore(t1)) {
126
127 Assertions.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
128 } else {
129
130 Assertions.assertTrue(previous.durationFrom(date) >= 0.999999 * step);
131 }
132 }
133 previous = date;
134 SpacecraftState state = propagator.propagate(date);
135 double[] e = measurement.
136 getObservedMeasurement().
137 estimateWithoutDerivatives(new SpacecraftState[] { state }).
138 getEstimatedValue();
139 for (int i = 0; i < m.length; ++i) {
140 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
141 }
142 }
143 Assertions.assertEquals(0.0, maxError, tolerance);
144 }
145
146 @BeforeEach
147 public void setUp() {
148 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
149
150 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
151 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
152 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
153 }
154
155 Context context;
156 NumericalPropagatorBuilder propagatorBuilder;
157
158 }