An efficient undifferenced method for estimating multi-GNSS high-rate clock corrections with data streams in real time
An efficient undifferenced method for estimating multi-GNSS high-rate clock corrections with data streams in real time
复制标题
一种利用数据流实时估计多 GNSS 高速时钟校正的高效无差异方法
DOI：
10.1007/s00190-019-01255-9
复制
发表时间：
2019
影响因子：
4.4
通讯作者：
Zhao Chuanbao
中科院分区：
文献类型：
--
作者：
Liu Teng;Zhang Baocheng;Yuan Yunbin;Zha Jiuping;Zhao Chuanbao
卫星钟改正是实现实时精密单点定位的关键。为充分提高多GNSS实时卫星钟差定位能力，提出了一种真实的实时高精度估计多GNSS高速率卫星钟差的方法。与现有文献中的历元差分方法不同，该方法基于非差观测值，建立函数模型，在提高处理效率的同时实现了全参数可达性。在该方法中，主要的数据处理是基于两个函数模型：全参数（FP）模型和高速率（HR）模型。在FP模型中，码和相位观测值都被使用，主要用于估计大量的相位模糊度，这实际上是时钟估计中最耗时的部分。在HR模型中，只利用相位观测值估计高速率时钟校正，其中引入了从FP模型获得的最新模糊度估计和相应的方差信息作为相位校正，以减小正规方程的大小，并保证HR处理的高处理效率。利用该方法，实现了四系统（GPS/GLONASS/Galileo/BeiDou）实时数据流的高速率（1 Hz）时钟校正量的实时估计，并进行了验证。将卫星时钟校正值编码为状态空间代表性校正值，并广播到用户端，以支持多GNSS RTPPP。仿真结果表明，该方法具有较高的计算效率，能够真实的实时提供1 Hz甚至更高速率的多GNSS时钟校正。将四系统实时卫星钟与GFZ的后处理产品进行了比较。对RTPPP的定位精度和收敛速度等定位性能进行了验证和分析。仿真结果表明，该方法在多GNSS系统实时高速时钟估计中具有良好的应用前景。
Precise satellite clock corrections are the key elements for the implementation of Real-Time Precise Point Positioning (RTPPP). To fully promote the capability of multi-GNSS RTPPP, an efficient method is proposed for the precise estimation of multi-GNSS high-rate satellite clock corrections in real time. Different from the epoch-differenced methods in the current literature, the proposed method is based on undifferenced observations and the function models are established to achieve high processing efficiency and full-parameter accessibility at the same time. In the proposed method, main data processing is performed based on two function models: the full-parameter (FP) model and the high-rate (HR) model. In the FP model, both code and phase observations are used, mainly for the estimation of the large number of phase ambiguities, which is actually the most time-consuming part in clock estimation. In the HR model, high-rate clock corrections are estimated with only phase observations, in which the latest ambiguity estimates and corresponding variance information obtained from the FP model are introduced as phase corrections to reduce the size of the normal equations and guarantee high processing efficiency for the HR processing. With the proposed method, real-time estimation of high-rate (1 Hz) clock corrections for a quad-system (GPS/GLONASS/Galileo/BeiDou) solution with real-time streams has been realized and validated. Satellite clock corrections are encoded to state-space representative corrections and broadcasted to the user side to support multi-GNSS RTPPP. Results show that the proposed method is highly efficient and can provide 1 Hz or even higher-rate clock corrections for multi-GNSS in real time. Quad-system real-time satellite clocks are compared with the post-processed products from GFZ. Positioning performances of RTPPP, including positioning accuracy and convergence speed, have also been validated and analyzed. All the results show that the proposed method is effective, efficient, accurate and promising in multi-GNSS real-time high-rate clock estimation.