Subsidence Monitoring System Using Real-Time GPS Sensors

Kai Borre, Kees de Jong and Christophe Pichot

Abstract:	Today GPS observables are so accurate that it makes sense to investigate if they can be used for subsidence monitoring at the mm-level. This challenge, of course, asks for using sophisticated filters and data handling. Most systematic errors are eliminated to some extent by using relative positioning techniques. The difficulties in ionospheric and tropospheric modeling set certain limits for the extension of the system: all baselines should be short and the height differences small. The ultimate difficulty is to cope with multipath effects. We exploit the well-known repetition of the satellite constellation every 24 hours. Efficient filters model this error source down to sub-millimeter level. Hence we have a system that works at the mm-level within a 24 hours period and at the sub-mm level as time proceeds. The software has both an initialization and a monitoring mode. The initialization period takes 24 hours, monitoring takes place in the 24 hour periods following the initialization by comparing the results from these periods with those from the initialization periods. Since the orbital repetition is not exactly 24 hours, the software determines the optimal repetition period. Also, it takes care that the same satellite configuration is used when comparing corresponding epochs. The software runs under MS Windows (TM). The number of receivers for which data can be processed simultaneously is limited only by the capacity of the data links. The developed software builds on the Scorpio receiver from Thales-Navigation. We believe the patented method makes a break-through for a new precise application of GPS.
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:	362 - 367
Cite this article:	Borre, Kai, de Jong, Kees, Pichot, Christophe, "Subsidence Monitoring System Using Real-Time GPS Sensors," 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. 362-367.
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