电离层时变特性约束的BDS长距离RTK定位算法

doi:10.11947/j.AGCS.2023.20220283

摘要/Abstract

摘要： 电离层误差是影响长距离GNSS定位性能的主要因素,通常采用无电离层组合消除电离层误差的影响,但无电离层组合存在观测噪声放大、在多系统多频数据时无法对单个频率的观测值进行单独处理,直接消除电离层参数使得无法对电离层参数施加约束,而电离层的先验信息,时空约束信息更易获得,为此本文对非组合定位模型中电离层误差的时变特性进行研究。在非组合定位模型中电离层参数常被估计为随机游走,功率谱密度决定了随机游走的过程,也表达了电离层误差的时变特性,通过对功率谱密度的研究,对电离层参数进行合理的约束来改善定位的性能。不需要经验模型及人为的给予电离层参数时变约束信息,而是通过顾及电离层实时特性的电离层观测值确定功率谱密度值,提供了简单实用的电离层时变约束方法。通过试验验证采用Vondrak平滑方法进行电离层延迟的最佳平滑,能在削弱观测噪声的同时反映电离层实时变化,求得的电离层功率谱密度能显著提升整周模糊度收敛时间,使定位性能达到最优。对电离层时变约束的BDS三频观测数据长距离RTK定位试验表明:静态和动态定位模式下均能实现模糊度的快速固定,可满足高精度实时定位的需求。

关键词: 长距离, 电离层延迟, 功率谱密度, 时变特性, Vondrak平滑

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

中图分类号:

P288

李军, 祝会忠, 徐爱功, 路阳阳, 雷啸挺. 电离层时变特性约束的BDS长距离RTK定位算法[J]. 测绘学报, 2023, 52(3): 383-396.

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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