Pressure Altitude Enhanced AGNSS Hybrid Receiver for a Mobile Terminal

Jani Käppi and Kimmo Alanen

Abstract:	The vertical positioning capability of GNSS receivers as a performance criterion will be more important in the near future due to upcoming location-based services setting stricter vertical positioning requirements. Vertical positioning accuracy particularly suffers in situations where there is poor satellite geometry, e.g., due to the low satellite elevation angle in high-rise buildings. The focus of this paper is to study ways to improve AGNSS performance in terms of vertical positioning accuracy and reliability by providing pressure altitude measurements for the GNSS positioning solution. Pressure measurements are obtained from an AGNSS receiver integrated MEMS pressure sensor. To cope with the bias and drift tendency of the pressure altitude, the reference pressure information is transmitted via a TCP/IP network. System performance was evaluated in an urban office environment both indoors and outdoors. Single-fix and navigation tests show that pressure altitude augmentation improves the vertical positioning capability and measurement geometry of the AGNSS receiver. Singlefix tests also indicated improvement on the time-to-firstfix estimates compared to the GNSS-only solution.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	1991 - 1997
Cite this article:	Käppi, Jani, Alanen, Kimmo, "Pressure Altitude Enhanced AGNSS Hybrid Receiver for a Mobile Terminal," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 1991-1997.
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