Quasi-optimal Satellite Selection Algorithm for Real-time Applications1

Chan-Woo Park and Jonathan P. How

Abstract:	This paper presents a quasi-optimal satellite geometry selection algorithm for navigation systems where a large number of ranging signals are available (e.g. LEO spacecraft navigation system using GPS, on-board ranging transmitter augmented CDGPS systems [14], combined (NAVSTAR and GLONASS) systems, and ground based pseudolite augmented systems). This algorithm is especially important for LEO spacecraft DGPS systems since there are limited numbers of channels on the receiver and the on-board computer has limited real-time processingca pability. However, typically, 12–15 NAVSTAR satellites and possibly a number of local ranging signals from other vehicles in the formation are visible to a LEO spacecraft. Thus, it is very important to select the subset of measurements that provides the best possible geometry. The algorithm presented in this paper provides near optimal geometries from the combined NAVSTAR, GLONASS, and local constellations, but dramatically reduces the computational load when compared to the true optimal method. In contrast to the other algorithms considered, this quasioptimal approach also allows other weighting factors to be included in the selection to account for differences in the signal quality and the covariance of the bias estimates. By includingthese weighting factors, the algorithm can select the measurement subset that ensures the best position and velocity estimates.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	3018 - 3028
Cite this article:	Park, Chan-Woo, How, Jonathan P., "Quasi-optimal Satellite Selection Algorithm for Real-time Applications1," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 3018-3028.
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