BDS long-range RTK positioning algorithm considering the time-varying properties of ionosphere

doi:10.11947/j.AGCS.2023.20220283

Abstract

Abstract: The ionospheric delay error is the main factor affecting the long-range GNSS positioning performance, and the ionospheric-free combination is usually used to eliminate the influence of the ionospheric delay. Ionosphere-free combination model enlarges the noise of the observation, and cannot independent process the observation information of each frequency in multi-system multi-frequency data processing. Directly eliminating the ionospheric parameters makes it impossible to impose constraints on the ionospheric parameters, but the prior information and time-space constraint information of the ionosphere can be obtained very well. Therefore, this paper studies the time-varying properties of the ionospheric error in the un-combined positioning model. In the uncombined positioning model, the ionospheric parameters are often estimated as random walks. The power spectral density determines the random walk process, and also expresses the time-varying properties of the ionospheric errors. Therefore, our research on the power spectral density leads to reasonable constraints on ionospheric parameters to improve the positioning performance. It does not require empirical models and artificial time-varying constraint information for ionospheric parameters, but determines the power spectral density by taking into account the real-time characteristics of the ionosphere, providing a simple and practical ionospheric time-varying constraint method. It is verified by experiments that the optimal smoothing of the ionospheric delay using the Vondrak smoothing can reflect the real-time changes of the ionosphere while weakening the observation noise. The obtained ionospheric power spectral density can optimize the positioning performance. The BDS three-frequency observation data long-range RTK positioning experiment with time-varying constraints on the ionosphere shows that: Both the static and dynamic modes can quickly realize the ambiguity fix, which can meet the needs of high-precision real-time positioning.

Key words: long-range, ionospheric delay, power spectral density, time-varying properties, Vondrak smoothing

CLC Number:

P288

LI Jun, ZHU Huizhong, XU Aigong, LU Yangyang, LEI Xiaoting. BDS long-range RTK positioning algorithm considering the time-varying properties of ionosphere[J]. Acta Geodaetica et Cartographica Sinica, 2023, 52(3): 383-396.

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