一种顾及先验约束的北斗观测数据多路径一步修正模型

A One-Step Multipath Delay Correction Model for BeiDou Satellite Observations with Prior Constraint

  • 摘要: 卫星观测数据质量是衡量系统服务性能的关键指标之一。多路径延迟作为导航定位服务中的主要误差源,是全球导航卫星系统数据处理领域的研究热点。针对多路径分步处理策略无法获得全局最优解的问题,提出一种基于先验约束的北斗卫星导航系统(BeiDou navigation satellite system, BDS)观测数据多路径实时修正模型。首先,基于提取的多路径延迟序列,利用全变分正则化算法实现多路径序列的分离与降噪;然后,利用最小二乘和自回归模型对多路径序列中趋势项与随机项进行一步建模处理;最后,以求解的多路径模型系数为先验信息,精化实时服务条件下BDS多路径处理模型。BDS实时精密单点定位实验表明,相较于传统多路径处理策略,经顾及先验约束的BDS观测数据一步修正后,BDS-2定位精度在E、N、U方向分别提升了10.6%~64.9%、0.0%~59.1%和12.6%~67.2%(B1I+B3I),BDS-3定位精度在E、N、U方向分别提升了13.9%、60.0%、45.9%(B1I+B3I)与19.1%、46.5%、23.9%(B1C+B2a)。所提的多路径处理模型可有效改善BDS实时定位应用中观测数据质量。

     

    Abstract:
      Objectives  Observation quality is one of the key issues to assess the performances of satellite navigation system. As the main error of positioning and navigation, the multipath delay mitigation has become the focus of the research in global navigation satellite system. Because the traditional multipath modelling strategy cannot obtain the global optimal solutions, this paper proposes a real-time multipath correction model for BeiDou navigation satellite system (BDS) observation with information constraints.
      Methods  Firstly, the regularization algorithm combined with total variation term is used to denoise and solve the multipath delay series based on the estimated BDS multipath delays. Secondly, the trend and random parts of multipath delays are separately processed and together modelled, in which the strategy of least square plus autoregression is used to estimate model coefficients of multipath delay model by one-step solution. Finally, the multipath mitigation model is further optimized by introducing the estimated model coefficients as the prior information constraints in the BDS real-time applications.
      Results  The results of real-time experiments of BDS precise point positioning show that, compared with the traditional strategy, the position accuracy of BDS-2 PPP in east (E), north (N) and up (U) directions can be improved with 10.6%-64.9%, 0.0%-59.1% and 12.6%-67.2% (B1I+B3I), respectively. Moreover, the position accuracy of BDS-3 PPP can be optimized with at least 13.9%, 60.0%, 45.9% (B1I+B3I) and 19.1%, 46.5%, 23.9% (B1C+B2a) in E, N and U directions, respectively.
      Conclusions  Therefore, the proposed mitigation multipath delays method can significantly improve the BDS observation quality in the BDS real-time positioning services.

     

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