基于钟差解耦的GNSS精密单点定位模糊度固定模型及效果分析

精密单点定位模糊度固定可以显著提升定位精度,钟差解耦模型作为一种重要的模糊度固定模型,却鲜有文献对其进行研究。本文首先给出了基于钟差解耦模型的用于模糊度固定的产品估计策略,分析了传统的消电离层模型和钟差解耦模型钟差重构形式的差异,导出了提取卫星码偏差的钟差估计模型。然后,深入研究了钟差解耦模型在钟差估计收敛速度等方面的优势。不同于其他模型将宽巷模糊度偏差视为天内常数,钟差解耦模型逐历元估计该偏差项,基于此展开对宽巷模糊度偏差天内时变特性的研究。最后,评价了解耦钟差的精度,并利用解耦钟差产品进行精密单点定位模糊度固定试验。结果表明,相比于提取卫星码偏差的卫星钟差估计模型,钟差解耦模型在钟差估计中的收敛速度更快,钟差产品更加稳定;宽巷模糊度偏差在天内较为稳定;解耦钟差产品具有较高的精度,相比于传统消电离层组合模型,基于该产品的精密单点定位模糊度固定可显著提升定位精度。

Modeling and effects analysis of GNSS precise point positioning ambiguity resolution based on the decoupled clock method

Precise point positioning with ambiguity resolution can significantly improve the positioning accuracy.However,as an important ambiguity resolution model,there are few literatures focused on the study of the decoupled clock model.Firstly,this paper introduces the product estimation strategy for ambiguity resolution based on the decoupled clock model,analyzes the differences of clock offsets between the conventional ionosphere-free model and the decoupled clock model,derives the satellite clock estimation model with satellite code bias extraction,and deeply investigates the advantages of the decoupled clock model in the convergence speed of satellite clock estimation.Different from other models,the wide-lane ambiguity bias of the decoupled clock model is time-varying in one day and estimated epoch by epoch.Based on this,the intra-day time-varying characteristics of wide-lane ambiguity bias are studied.Finally,the accuracy of the decoupled clocks is evaluated,and the precise point positioning ambiguity resolution experiment is carried out by using the decoupled clock products.The results show that,compared with the satellite clock estimation model with satellite code bias extraction,the decoupled clock model has faster convergence speed,and the clock product is more stable.The wide-lane ambiguity bias is relatively stable in one day,and the decoupled clock product has high accuracy.Compared with the conventional ionosphere-free model,the precise point positioning ambiguity resolution based on the decoupled clock product can significantly improve the positioning accuracy.