Study of Improved Observation Modeling for Surveying Type Applications in Multipath Environment

B. Richter and H.J. Euler

Abstract:	Besides ionospheric and tropospheric effects, multipath and diffraction are the factors which can most limit the accuracy of real-time applications. Phase observations contaminated by diffraction may have unwanted effects in kinematic applications and this would limit the suitability of monitoring systems based on GPS as well as pure GPS surveying real-time applications. The concept of a self-calibrating weighting model is presented which can be used to weight down or completely eliminate poor signals from processing. The Signal- to-Noise ratio (SNR) is highly correlated with signals contaminated by diffraction. The problem with using the SNR for the weighting model is that the SNR is dependent on the setup, which means that different receiver/ antenna combinations and cables with varying resistances show different elevation dependent SNR patterns. Even a different location would have an influence on this pattern. For real-time applications it is therefore necessary to automatically calibrate a weighting model, which is based on the SNR. Our paper describes the advantages of such a self-calibrating weighting model compared to purely elevation dependent weighting models. The efficiency of the used model is demonstrated for a kinematic real-time application as well as for a typical static survey. The kinematic test was conducted on the world’s largest suspension bridge in Hong Kong. Such monitoring applications, where the place of mounting a GPS-antenna is almost given, benefit strongly from this approach.
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:	1048 - 1055
Cite this article:	Richter, B., Euler, H.J., "Study of Improved Observation Modeling for Surveying Type Applications in Multipath Environment," 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. 1048-1055.
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