Detection of Cycle Slips and Multipath in GNSS RTK Precise Point Positioning

M. Kamimura, R. Tomita, T. Nagano, A. Chabata, Y. Kubo, and S. Sugimoto

Abstract:	In this paper, we present methods of detecting cycle slips and multipath in GNSS for RTK-PPP, based on GR (Gnss Regressive) models and the statistical tests for the innovation processes and difference between successive-time estimates of integer ambiguities, with applying the Kalman filter. In order to estimate the unknown values such as the position, velocity and integer ambiguities by the Kalman filter, detection of cycle slips and multipath is implemented by using the statistical hypothesis tests on the byproduct of the estimation. If a cycle slip occurs, the statistical property of the innovation process changes. Therefore, we formulate two hypotheses such that the change of the innovation process does not occur (null hypothesis), and the change occurs (alternative hypothesis). The second method of the statistical test based on Kalman filtering is developed in this paper. A main idea of this statistical test is based on deriving the statistical properties of the difference between two successive-time filtering estimates of integer ambiguities. Especially, the mean vector and covariance matrix of difference between two successive-time filtering estimates are derived by the recursive formula including Lyapunov difference equations. The two tests described above are implemented at every recursion of the Kalman filter. Detecting the changes of C/A or P(Y) psuedoranges, we regard that the corresponding GNSS observables are af-fected by the multipath such that these observables are removed from positioning algorithms. Also, however, when the change of L1 or L2 carrier phases are detected, we regard that cycle slips occur in carrier phases from the corresponding GNSS satellites, then utilize these measurement data of L1 and L2 carrier phases for re-initializing the estimates of integer ambiguities, on the purpose of maintaining the accuracy of GNSS RTK-PPP. Finally experimental results of the data received by the automobile in Chofu city, Tokyo, Japan are shown, and discussed for the feasibility of our methods presented in this paper, for detecting cycle slips and multipath, and for recovering and maintaining the accuracy of the positioning in GNSS RTK-PPP.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1056 - 1067
Cite this article:	Kamimura, M., Tomita, R., Nagano, T., Chabata, A., Kubo, Y., Sugimoto, S., "Detection of Cycle Slips and Multipath in GNSS RTK Precise Point Positioning," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 1056-1067.
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