Real Time Autonomous Orbit Determi GEO Satellite Using GPSnation of

Mikhail Vasilyev

Abstract:	The GPS technique is considered now as a preferred navi-gation tool to minimize GEO mission support from ground stations and to implement the real time autonomous sys-tems for orbit determination. There are two main and closely connected problems in GEO navigation using GPS: poor GEO-GPS mutual geometry and moderate stability of the standard onboard clocks. The first point means that maximum three GPS satellites are visible simultaneously. It makes the standard snapshot navigation solution inapplica-ble. A conventional approach for solving this problem is to take into account a satellite motion model and to perform the differential orbit correction and the clock model pa-rameters determination. It is shown in the paper that the navigation accuracy de-pends mainly on the quality of two models: the satellite motion and onboard clock models, rather than the GPS sat-ellites visibility conditions. Since the present-day space qualified processors are capable of real time computing of the precise satellite orbit model, the quality of the onboard clock model gets a special significance, especially for mod-erate stability 10 -9 quartz oscillators, which are typically used in GPS receivers. It is proposed to use the stochastic “random walk” model based on the Kalman filter for clock modeling. It is demon-strated that this model is much more efficient than classical polynomial one for the GEO navigation and allows, to-gether with the precise satellite dynamic model, to achieve three-dimensional accuracy of the order of 30 meters even in case of standard TCXO oscillator.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	451 - 458
Cite this article:	Vasilyev, Mikhail, "Real Time Autonomous Orbit Determi GEO Satellite Using GPSnation of," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 451-458.
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