Improving Kinematic LEO POD with the Use of a Space-Based and Ground-Based GPS Transceiver Constellation: Feasibility Study

Dorota Grejner-Brzezinska, Chang-Ki Hong, and Tae-Suk Bae

Abstract:	Kinematic orbit determination of satellites on Low Earth Orbits (LEOs) based on GPS observables offers a viable alternative to the predominantly dynamic orbit determination approaches. Since kinematic orbit determination (OD) requires neither dynamic force models nor the physical properties of LEO, the OD procedures are much simpler and computationally efficient compared to the dynamic OD approach. However, the quality and continuity of kinematic OD strongly depends on the quality and continuity of the GPS data, and the geometry between the GPS satellites, LEO and the ground-based tracking stations. Since the kinematic method displays a strong dependence on the tracking data quality and continuity, an alternative approach to strengthen the constellation geometry of the positioning satellites is proposed and discussed in this paper. One solution to improve the quality of kinematic OD might be to place pseudolite transceivers (which transmit and receive GPS signals) on board LEO satellites, which would allow determination of relative positions between the vehicles, augmenting the GPS constellation, and potentially acting as a self-constellation when limited GPS is available. Another approach would be to place a constellation of GPS pseudolite transceivers, sending a ranging signal to LEO (and higher orbit) satellites, on the ground, to strengthen the geometry and to improve the continuity. In this paper we present a feasibility study of the simulated configuration, which uses orbiting GPS pseudolite transceivers (such as those designed for formation flying). In addition to the orbiting transceivers, the simulation of the observing system includes ground- based pseudolite transceivers. A feasibility analysis of the effects of combining the orbiting and ground-based transceivers with the GPS constellation for the kinematic LEO OD is carried out. A priori covariance analysis is presented to assess the model’s quality and viability for improved OD. The expected results could be used in planning future LEO constellations and their tracking networks. In addition, we considered the combination of GPS and the upcoming European GNSS (Global Navigation Satellite System) Galileo.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	643 - 651
Cite this article:	Grejner-Brzezinska, Dorota, Hong, Chang-Ki, Bae, Tae-Suk, "Improving Kinematic LEO POD with the Use of a Space-Based and Ground-Based GPS Transceiver Constellation: Feasibility Study," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 643-651.
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