Precise Orbit Determination of Global Navigation Satellite System of ...

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Chapter 8 Geostationary Orbit Determination And Prediction During Satellite Maneuvers On the other side, the accuracy of kinematic orbit determination is not related to the dynamic force models, it only dependents on the observation noise and geometrical distribution of the ground tracking stations. The lower the noise of observation, the better the accuracy of the kinematic orbit determination. Figure 8-7, that shows the results of kinematic orbit determination using carrier phase observation, verifies the conclusion above. Difference (meter) 10 8 6 4 2 0 -2 -4 -6 -8 -10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Tim e (hour) Figure 8-7 Kinematic Orbit Determination of Geostationary Satellite using Carrier Phase Observation 8.2.2 Orbit Determination With Maneuver Operation Following are the results of orbit determination during satellite maneuvers using the kinematic and the dynamic methods. The observations are still ranges with 1 m random noise. The satellite maneuver starts at 5 h 00 m and stops at 10 h 00 m . The maneuver lasts 5 hours. The maneuver accelerations are assumed as follows −7 2 x&= y& = 8× 10 m/ s � � z&= 0 � 106 dx dy dz (8-53) Eq. (8-53) means the satellite maneuver force push the satellite to move in the east direction in the in-plane of the orbit. Difference (meter) 20 15 10 5 0 -5 -10 -15 -20 Maneuver Start Maneuver Stop 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hour) Figure 8-8 Kinematic Orbit Determination of Geostationary Satellite during Maneuver dx dy dz
Chapter 8 Geostationary Orbit Determination And Prediction During Satellite Maneuvers Difference (meter) 30 20 10 0 -10 -20 Maneuver Start -30 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hour) Maneuver Stop Figure 8-9 Dynamic Orbit Determination of Geostationary Satellite during Maneuver Comparing Figure 8-5 with Figure 8-8, it shows that there are no great differences found for orbit determination using kinematic method with or without maneuver operations. This property can be used for improving maneuver force model. Comparing Figure 8-6 with Figure 8-9 it is obvious that during satellite maneuver, the accuracy of the dynamic orbit determination is significantly degraded. For some larger maneuver force, the accuracy of dynamic orbit determination would be worse. This is because in the dynamic method, no precise maneuver force models are included. Even if the maneuver force models were included, but there were some unmodeled or mismodeled errors, the accuracy of the dynamic orbit determination would also be reduced. 8.3 Maneuver Force Model For post-processing, it is sufficient to use the kinematic method for orbit determination during satellite maneuver. For real-time navigation application, users usually need the so-called satellite ephemeris, i.e. predicted orbit, as a reference to compute their positions and velocities. The kinematic method can be used to determine the satellite orbit during satellite maneuver, but it cannot be used to predict orbit. For orbit prediction, the dynamic method is still needed and the maneuver force should be included in the satellite dynamic force models. First let us see the accuracy of orbit prediction using current dynamic models without satellite maneuver force model included. Figure 8-10 and Figure 8-11 show the accuracy of orbit prediction due to the maneuver accelerations expressed by Eq.(8-53). The maneuver operation lasts about 5 hours. Figure 8-12 shows the accuracy of orbit prediction due to the maneuver accelerations written below and the maneuver operation lasts about 48 minutes −5 2 x&= y& = 8× 10 m/ s � � z&= 0 � 107 dx dy dz (8-54)
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PRECISE ORBIT DETERMINATION OF GLOB
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Summary GNSS-2 (Global Navigation S
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3.2.2.1 Principle..................
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9.3.3 The Effect of Distribution of
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Chapter 1 Introduction 1.2 Developm
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Chapter 2 Observations of Orbit Det
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Chapter 3 Orbit Tracking System and
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Chapter 4 Major Error Sources of Sa
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Chapter 5 Perturbation Models of IG
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Page 64 and 65: Chapter 5 Perturbation Models of IG
Page 74 and 75: Chapter 6 Algorithms of Orbit Deter
Page 94 and 95: Chapter 7 Orbit Determination Using
Page 104 and 105: Chapter 8 Geostationary Orbit Deter
Page 122 and 123: Chapter 9 Software and Simulation R
Page 152 and 153: Conclusion 144
Page 154 and 155: References Carpino M. (1995): SAEG
Page 156 and 157: References Klobuchar, J. A.(1996):
Page 158 and 159: References Traquilla, J. M. and J.
Page 160 and 161: Acknowledgments 152
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