GPS and Pseudolite Integration for Deformation Monitoring Applications

Liwen Dai, Jun Zhang, Chris Rizos, Shaowei Han and Jinling Wang

Abstract:	Due to the millimeter-level resolution of the carrier phase observable, the Global Positioning System (GPS) tech- nology has been widely used for monitoring crustal mo- tion and ground subsidence, and more recently for defor- mation monitoring of man-made structures such as bridges, dams, buildings, etc. However, due to the limita- tions of satellite geometry, the accuracy of the height component is generally 2 or 3 times worse than the hori- zontal components. Pseudolites, which are ground-based instruments that transmit GPS-like signals, can improve the satellite-receiver geometry. Hence, in principle, they can be used as additional range observations to improve the performance of a GPS-based deformation monitoring system. There are many additional effects that need to be consid- ered in hybrid GPS-pseudolite systems compared to GPS- only systems. These include pseudolite location- dependent errors, multipath, and troposphere delay ef- fects, and must be modeled in a different way to the GPS signals. In this paper some theoretical analyses of these factors will be presented in order to determine whether the use of pseudolite signals can indeed improve GPS per- formance. In particular, the effects of additional pseu- dolite signal(s) on ambiguity resolution and positioning accuracy have been investigated. A few experiments have been carried out using NovAtel receivers with three IntegriNautics IN200CXL pseudolite instruments. The results indicate that the accuracy of the height component can indeed be improved to the almost same level as the horizontal components. The accuracy, reliability, availability and integrity of the solutions from an integrated GPS and pseudolite system can also be sig- nificantly improved.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	1 - 8
Cite this article:	Dai, Liwen, Zhang, Jun, Rizos, Chris, Han, Shaowei, Wang, Jinling, "GPS and Pseudolite Integration for Deformation Monitoring Applications," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 1-8.
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