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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.Assert;
29 import org.junit.Before;
30 import org.junit.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.ObservableSatellite;
35 import org.orekit.estimation.measurements.ObservedMeasurement;
36 import org.orekit.estimation.measurements.gnss.InterSatellitesPhase;
37 import org.orekit.estimation.measurements.modifiers.Bias;
38 import org.orekit.gnss.Frequency;
39 import org.orekit.orbits.KeplerianOrbit;
40 import org.orekit.orbits.Orbit;
41 import org.orekit.orbits.OrbitType;
42 import org.orekit.orbits.PositionAngle;
43 import org.orekit.propagation.Propagator;
44 import org.orekit.propagation.SpacecraftState;
45 import org.orekit.propagation.analytical.KeplerianPropagator;
46 import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
47 import org.orekit.propagation.events.InterSatDirectViewDetector;
48 import org.orekit.time.AbsoluteDate;
49 import org.orekit.time.FixedStepSelector;
50 import org.orekit.time.TimeScalesFactory;
51 import org.orekit.utils.PVCoordinates;
52
53 public class InterSatellitesPhaseBuilderTest {
54
55 private static final double SIGMA = 0.5;
56 private static final double BIAS = -0.01;
57 private static final double WAVELENGTH = Frequency.G01.getWavelength();
58
59 private MeasurementBuilder<InterSatellitesPhase> getBuilder(final RandomGenerator random,
60 final ObservableSatellite receiver,
61 final ObservableSatellite remote) {
62 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] { SIGMA * SIGMA });
63 MeasurementBuilder<InterSatellitesPhase> isrb =
64 new InterSatellitesPhaseBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
65 1.0e-10,
66 new GaussianRandomGenerator(random)),
67 receiver, remote, WAVELENGTH, SIGMA, 1.0);
68 isrb.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 isrb;
74 }
75
76 @Test
77 public void testForward() {
78 doTest(0xc82a56322345dc25l, 0.0, 1.2, 2.8 * SIGMA);
79 }
80
81 @Test
82 public void testBackward() {
83 doTest(0x95c10149c4891232l, 0.0, -1.0, 2.6 * 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 generator.addPropagator(buildPropagator());
93 generator.addPropagator(buildPropagator());
94 ObservableSatellite receiver = generator.addPropagator(buildPropagator());
95 generator.addPropagator(buildPropagator());
96 final Orbit o1 = context.initialOrbit;
97
98 final Orbit o2 = new KeplerianOrbit(new PVCoordinates(o1.getPVCoordinates().getPosition(),
99 o1.getPVCoordinates().getVelocity().negate()),
100 o1.getFrame(), o1.getDate(), o1.getMu());
101 ObservableSatellite remote = generator.addPropagator(new KeplerianPropagator(o2));
102 final double step = 60.0;
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109 generator.addScheduler(new EventBasedScheduler<>(getBuilder(new Well19937a(seed), receiver, remote),
110 new FixedStepSelector(step, TimeScalesFactory.getUTC()),
111 generator.getPropagator(receiver),
112 new InterSatDirectViewDetector(context.earth, new KeplerianPropagator(o2)),
113 SignSemantic.FEASIBLE_MEASUREMENT_WHEN_POSITIVE));
114
115 final double period = o1.getKeplerianPeriod();
116 AbsoluteDate t0 = o1.getDate().shiftedBy(startPeriod * period);
117 AbsoluteDate t1 = o1.getDate().shiftedBy(endPeriod * period);
118 SortedSet<ObservedMeasurement<?>> measurements = generator.generate(t0, t1);
119
120
121 Propagator propagator1 = buildPropagator();
122 Propagator propagator2 = new KeplerianPropagator(o2);
123
124 double maxError = 0;
125 AbsoluteDate previous = null;
126 AbsoluteDate tInf = t0.compareTo(t1) < 0 ? t0 : t1;
127 AbsoluteDate tSup = t0.compareTo(t1) < 0 ? t1 : t0;
128 for (ObservedMeasurement<?> measurement : measurements) {
129 AbsoluteDate date = measurement.getDate();
130 double[] m = measurement.getObservedValue();
131 Assert.assertTrue(date.compareTo(tInf) >= 0);
132 Assert.assertTrue(date.compareTo(tSup) <= 0);
133 if (previous != null) {
134
135
136
137 Assert.assertTrue(date.durationFrom(previous) >= 0.999999 * step);
138 }
139 previous = date;
140 double[] e = measurement.estimate(0, 0,
141 new SpacecraftState[] {
142 propagator1.propagate(date),
143 propagator2.propagate(date)
144 }).getEstimatedValue();
145 for (int i = 0; i < m.length; ++i) {
146 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
147 }
148 }
149 Assert.assertEquals(0.0, maxError, tolerance);
150 }
151
152 @Before
153 public void setUp() {
154 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
155
156 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true,
157 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
158 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
159 }
160
161 Context context;
162 NumericalPropagatorBuilder propagatorBuilder;
163
164 }