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

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Chapter 8 Geostationary Orbit Determination And Prediction During Satellite Maneuvers Clearly from Eq.(8-57), the acceleration is in the earth-fixed system, which cannot be directly compared with the acceleration from the dynamic model. The coordinate system conversion should be made before. The transformation can de done as follows. Assuming [ N ] is the nutation transformation matrix, [ P ] the precession matrix, [ C ] the polar motion matrix and [ G ] the sidereal time transformation matrix, then transformations from the earth-fixed coordinate system to inertial coordinate system are ϖ ϖ ri = [ N][ P][ C][ G] re (8-58) ϖ& ϖ ϖ r = [ N][ P][ C] Gr ] & + [ Gr & ] (8-59) { } { } i e e ϖ& ϖ ϖ r [ N][ P][ C] [ Gr ] & [ Gr & ] & i = e +2 e (8-60) where ϖ ϖ ri, re ϖϖ r& , & i re ϖϖ r& , r& position vectors of satellite in the inertial and the earth-fixed systems, respectively velocity vectors of satellite in the inertial and the earth-fixed systems, respectively i e acceleration vectors of satellite in the inertial and the earth-fixed systems, respectively Normally ϖ r &and [ G & ] are very small, therefore the product of [ & ϖ ] & can be neglected. According to the method described above, using simulation data, the results of orbit prediction during satellite maneuvers are shown in Figure 8-13 and Figure 8-14. For the maneuver operated at the acceleration of Eq.(8-53), the orbit prediction during satellite maneuver is drawn as in Figure 8-13; for the maneuver acceleration of Eq.(8-54), the orbit prediction is drawn in Figure 8-14. In the orbit prediction, it is assumed that 50% of maneuver acceleration is modeled by nominal maneuver force model, Eq.(8-55) and Eq.(8-56); 20% of maneuver acceleration were corrected by Eq.(8-57), which was updated at the rate of about 60 minutes for Figure 8-13 and 10-15 minutes for Figure 8-14 by kinematic orbit determination results, the remaining 30% were unmodeled maneuver force errors that were not corrected during orbit prediction. 110 Gr e Figure 8-13 Orbit Prediction during Satellite Maneuver
Chapter 8 Geostationary Orbit Determination And Prediction During Satellite Maneuvers Figure 8-14 Orbit Prediction during Satellite Maneuver Comparing Figure 8-10 with Figure 8-13 and Figure 8-12 with Figure 8-14, it can be seen that the accuracies of predicted orbit are significantly enhanced by the maneuver force models that are updated by kinematic orbit determination. In Figure 8-11, the accuracy of prediction orbit is about 300 meters for 5 hours of maneuver operation, but in Figure 8-13, the accuracy of prediction orbit is about 5 meters for 5 hours of maneuver operation. In Figure 8-12, the accuracy of prediction orbit is about 300 meters after 48 minutes of maneuver operation, but in Figure 8-14, the accuracy of prediction orbit is about 5-10 meters after 48 minutes of maneuver operation. It should be noted again that in the results above, 30% unmodeled maneuver force errors are assumed, which were not corrected during orbit determination and prediction. If maneuver force model is more accurately or the accuracy of observation is increased, the time of orbit prediction will be longer. 111
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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 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
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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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Precise Orbit Determination of Global Navigation Satellite System of ...

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