Data Screening and Quality Analysis for Kinematic Orbit Determination of CHAMP Satellite

Tae-Suk Bae, Jay H. Kwon and Dorota A. Grejner-Brzezinska

Abstract:	Kinematic orbit determination of the Low Earth Orbiters (LEO) based on GPS observable 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 the LEO, the OD procedures are much simpler and computationally efficient than the dynamic OD approach. However, the quality of kinematic POD strongly depends on the quality and continuity of GPS data, and the geometry between the GPS satellites, LEO and the ground stations. The main purpose of this paper is to present the analysis of the GPS data quality and the data prescreening procedures for the kinematic orbit determination of the CHAMP satellite (German CHAllenging Minisatellite Payload, launched on July 15, 2000). Since, as mentioned above, the accuracy of the kinematic orbit determination highly depends on the configuration of GPS satellites as well as the ground stations, the discussion and the test results related to various configurations are presented. Since kinematic method displays a strong dependence on the data quality and continuity, the data prescreening is of a major importance. The prescreening of the data is mainly composed of detection of cycle slips (CS) for CHAMP and the ground stations. Two test quantities, namely the one-way ion-residual of phase and phase/range linear combinations, as well as wide-lane combination are used for the CS detection. While the ground stations show less than 3 % of cycle slips, CHAMP shows much higher number (about 5.5%) of cycle slips for the period of 24 hours, based on the test data analyzed here. It should be mentioned however, that the classical methods of CS detection were found not fully reliable for a LEO moving very fast (CHAMP: ~7.6 km/sec) in the middle of the ionospheric layer. In order to analyze the reliability of the classical method of CS detection in that case, a dynamic solution was used as a true reference. The CS analysis, their effect on the continuity and the quality of the orbit, the effects of the geometry as well as the elevation cut off and processing batch length on the final kinematic orbit accuracy are presented in this paper.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	771 - 777
Cite this article:	Bae, Tae-Suk, Kwon, Jay H., Grejner-Brzezinska, Dorota A., "Data Screening and Quality Analysis for Kinematic Orbit Determination of CHAMP Satellite," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 771-777.
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