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17  package org.orekit.estimation.measurements.modifiers;
18  
19  import java.util.List;
20  
21  import org.hipparchus.geometry.euclidean.threed.Vector3D;
22  import org.junit.Assert;
23  import org.junit.Test;
24  import org.orekit.attitudes.LofOffset;
25  import org.orekit.estimation.Context;
26  import org.orekit.estimation.EstimationTestUtils;
27  import org.orekit.estimation.measurements.EstimatedMeasurement;
28  import org.orekit.estimation.measurements.ObservedMeasurement;
29  import org.orekit.estimation.measurements.gnss.InterSatellitesPhase;
30  import org.orekit.estimation.measurements.gnss.InterSatellitesPhaseMeasurementCreator;
31  import org.orekit.frames.LOFType;
32  import org.orekit.gnss.Frequency;
33  import org.orekit.orbits.CartesianOrbit;
34  import org.orekit.orbits.Orbit;
35  import org.orekit.orbits.OrbitType;
36  import org.orekit.orbits.PositionAngle;
37  import org.orekit.propagation.BoundedPropagator;
38  import org.orekit.propagation.EphemerisGenerator;
39  import org.orekit.propagation.Propagator;
40  import org.orekit.propagation.SpacecraftState;
41  import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
42  import org.orekit.utils.TimeStampedPVCoordinates;
43  
44  public class OnBoardAntennaInterSatellitesPhaseModifierTest {
45  
46      private static final Frequency FREQUENCY = Frequency.G01;
47  
48      @Test
49      public void testPreliminary() {
50  
51          // this test does not check OnBoardAntennaInterSatellitesPhaseModifier at all,
52          // it just checks InterSatellitesPhaseMeasurementCreator behaves as necessary for the other test
53          // the *real* test is testEffect below
54          Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
55  
56          final NumericalPropagatorBuilder propagatorBuilder =
57                          context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true,
58                                                1.0e-6, 60.0, 0.001);
59          propagatorBuilder.setAttitudeProvider(new LofOffset(propagatorBuilder.getFrame(), LOFType.LVLH));
60  
61          // create perfect inter-satellites phase measurements without antenna offset
62          final TimeStampedPVCoordinates original = context.initialOrbit.getPVCoordinates();
63          final Orbit closeOrbit = new CartesianOrbit(new TimeStampedPVCoordinates(context.initialOrbit.getDate(),
64                                                                                   original.getPosition().add(new Vector3D(1000, 2000, 3000)),
65                                                                                   original.getVelocity().add(new Vector3D(-0.03, 0.01, 0.02))),
66                                                      context.initialOrbit.getFrame(),
67                                                      context.initialOrbit.getMu());
68          final Propagator closePropagator = EstimationTestUtils.createPropagator(closeOrbit,
69                                                                                  propagatorBuilder);
70          final EphemerisGenerator generator = closePropagator.getEphemerisGenerator();
71          closePropagator.propagate(context.initialOrbit.getDate().shiftedBy(3.5 * closeOrbit.getKeplerianPeriod()));
72          final BoundedPropagator ephemeris = generator.getGeneratedEphemeris();
73          final Propagator p1 = EstimationTestUtils.createPropagator(context.initialOrbit,
74                                                                             propagatorBuilder);
75          final int    ambiguity         = 0;
76          final double localClockOffset  = 0.137e-6;
77          final double remoteClockOffset = 469.0e-6;
78          final List<ObservedMeasurement<?>> spacecraftCenteredMeasurements =
79                          EstimationTestUtils.createMeasurements(p1,
80                                                                 new InterSatellitesPhaseMeasurementCreator(ephemeris,
81                                                                                                            FREQUENCY,
82                                                                                                            ambiguity,
83                                                                                                            localClockOffset,
84                                                                                                            remoteClockOffset,
85                                                                                                            Vector3D.ZERO,
86                                                                                                            Vector3D.ZERO),
87                                                                 1.0, 3.0, 300.0);
88  
89          // create perfect inter-satellites phase measurements with antenna offset
90          final double xOffset1 = -2.5;
91          final double yOffset2 =  0.8;
92          final Propagator p2 = EstimationTestUtils.createPropagator(context.initialOrbit,
93                                                                     propagatorBuilder);
94          final List<ObservedMeasurement<?>> antennaCenteredMeasurements =
95                          EstimationTestUtils.createMeasurements(p2,
96                                                                 new InterSatellitesPhaseMeasurementCreator(ephemeris,
97                                                                                                            FREQUENCY,
98                                                                                                            ambiguity,
99                                                                                                            localClockOffset,
100                                                                                                           remoteClockOffset,
101                                                                                                           new Vector3D(xOffset1, 0, 0),
102                                                                                                           new Vector3D(0, yOffset2, 0)),
103                                                                1.0, 3.0, 300.0);
104 
105         for (int i = 0; i < spacecraftCenteredMeasurements.size(); ++i) {
106             InterSatellitesPhase sr = (InterSatellitesPhase) spacecraftCenteredMeasurements.get(i);
107             InterSatellitesPhase ar = (InterSatellitesPhase) antennaCenteredMeasurements.get(i);
108             Assert.assertEquals(0.0, sr.getDate().durationFrom(ar.getDate()), 2.0e-8);
109             Assert.assertTrue((ar.getObservedValue()[0] - sr.getObservedValue()[0]) * FREQUENCY.getWavelength() >= -1.0);
110             Assert.assertTrue((ar.getObservedValue()[0] - sr.getObservedValue()[0]) * FREQUENCY.getWavelength() <= -0.36);
111         }
112     }
113 
114     @Test
115     public void testEffect() {
116 
117         Context context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
118 
119         final NumericalPropagatorBuilder propagatorBuilder =
120                         context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true,
121                                               1.0e-6, 60.0, 0.001);
122         propagatorBuilder.setAttitudeProvider(new LofOffset(propagatorBuilder.getFrame(), LOFType.LVLH));
123 
124         // create perfect inter-satellites phase measurements without antenna offset
125         final TimeStampedPVCoordinates original = context.initialOrbit.getPVCoordinates();
126         final Orbit closeOrbit = new CartesianOrbit(new TimeStampedPVCoordinates(context.initialOrbit.getDate(),
127                                                                                  original.getPosition().add(new Vector3D(1000, 2000, 3000)),
128                                                                                  original.getVelocity().add(new Vector3D(-0.03, 0.01, 0.02))),
129                                                     context.initialOrbit.getFrame(),
130                                                     context.initialOrbit.getMu());
131         final Propagator closePropagator = EstimationTestUtils.createPropagator(closeOrbit,
132                                                                                 propagatorBuilder);
133         final EphemerisGenerator generator = closePropagator.getEphemerisGenerator();
134         closePropagator.propagate(context.initialOrbit.getDate().shiftedBy(3.5 * closeOrbit.getKeplerianPeriod()));
135         final BoundedPropagator ephemeris = generator.getGeneratedEphemeris();
136         final Propagator p1 = EstimationTestUtils.createPropagator(context.initialOrbit,
137                                                                            propagatorBuilder);
138         final int    ambiguity         = 0;
139         final double localClockOffset  = 0.137e-6;
140         final double remoteClockOffset = 469.0e-6;
141         final List<ObservedMeasurement<?>> spacecraftCenteredMeasurements =
142                         EstimationTestUtils.createMeasurements(p1,
143                                                                new InterSatellitesPhaseMeasurementCreator(ephemeris,
144                                                                                                           FREQUENCY,
145                                                                                                           ambiguity,
146                                                                                                           localClockOffset,
147                                                                                                           remoteClockOffset,
148                                                                                                           Vector3D.ZERO,
149                                                                                                           Vector3D.ZERO),
150                                                                1.0, 3.0, 300.0);
151 
152         // create perfect inter-satellites phase measurements with antenna offset
153         final Vector3D apc1 = new Vector3D(-2.5, 0.0, 0);
154         final Vector3D apc2 = new Vector3D( 0.0, 0.8, 0);
155         final Propagator p2 = EstimationTestUtils.createPropagator(context.initialOrbit,
156                                                                    propagatorBuilder);
157         final List<ObservedMeasurement<?>> antennaCenteredMeasurements =
158                         EstimationTestUtils.createMeasurements(p2,
159                                                                new InterSatellitesPhaseMeasurementCreator(ephemeris,
160                                                                                                           FREQUENCY,
161                                                                                                           ambiguity,
162                                                                                                           localClockOffset,
163                                                                                                           remoteClockOffset,
164                                                                                                           apc1, apc2),
165                                                                1.0, 3.0, 300.0);
166 
167         final Propagator p3 = EstimationTestUtils.createPropagator(context.initialOrbit,
168                                                                    propagatorBuilder);
169 
170         OnBoardAntennaInterSatellitesPhaseModifier modifier = new OnBoardAntennaInterSatellitesPhaseModifier(apc1, apc2);
171         for (int i = 0; i < spacecraftCenteredMeasurements.size(); ++i) {
172             InterSatellitesPhase sr = (InterSatellitesPhase) spacecraftCenteredMeasurements.get(i);
173             sr.addModifier(modifier);
174             EstimatedMeasurement<InterSatellitesPhase> estimated = sr.estimate(0, 0, new SpacecraftState[] {
175                                                                                          p3.propagate(sr.getDate()),
176                                                                                          ephemeris.propagate(sr.getDate())
177                                                                                      });
178             InterSatellitesPhase ar = (InterSatellitesPhase) antennaCenteredMeasurements.get(i);
179             Assert.assertEquals(0.0, sr.getDate().durationFrom(ar.getDate()), 2.0e-8);
180             Assert.assertEquals(ar.getObservedValue()[0] * FREQUENCY.getWavelength(), estimated.getEstimatedValue()[0] * FREQUENCY.getWavelength(), 2.0e-5);
181         }
182 
183     }
184 
185 }
186 
187