Since its full operation in 2020, BeiDou Satellite Navigation System (BDS) has provided global services with highly precise Positioning, Navigation, and Timing (PNT) as well as unique short-message communication. More and more academics focus on multi-frequency Precise Point Positioning (PPP) models, but few on BDS five-frequency PPP models. Therefore, this study using the uncombined and Ionospheric-Free (IF) observations develops five BDS five-frequency PPP models and compares them with the traditional dual-frequency model, known as Dual-frequency IF (DF) model. Some biases such as Inter-Frequency Biases (IFB) and Differential Code Bias (DCB) are also addressed. With the data collected from 20 stations, the BDS dual- and five-frequency PPP models are comprehensively evaluated in terms of the static and simulated kinematic positioning performances. Besides, the study also analyzes some by-product estimated parameters in five-frequency PPP models such as Zenith Troposphere Delay (ZTD). The results of experiment show that five-frequency PPP models have different levels of improvement compared with the DF model. In the static mode, the one single Five-Frequency IF combination (FF5) model has the best positioning consequent, especially in the up direction, and in the simulated kinematic mode, the Three Dual-frequency IF combinations (FF3) model has the largest improvement in convergence time.

中文翻译：

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五频北斗精密单点定位建模与评估

自2020年全面运行以来，北斗卫星导航系统（BDS）以高精度的定位、导航和授时（PNT）以及独特的短消息通信，为全球提供服务。越来越多的学者关注多频精确点定位（PPP）模型，但很少关注北斗五频PPP模型。因此，本研究利用未组合和无电离层（IF）观测建立了五个北斗五频PPP模型，并将它们与传统的双频模型，即双频IF（DF）模型进行了比较。还解决了一些偏差，例如频率间偏差 (IFB) 和差分码偏差 (DCB)。结合20个站点的数据，对北斗双频和五频PPP模型的静态和模拟运动定位性能进行综合评价。此外，研究还分析了天顶对流层延迟（ZTD）等五频PPP模型中的一些副产品估计参数。实验结果表明，五频PPP模型与DF模型相比有不同程度的提升。在静态模式下，单个五频中频组合（FF5）模型的定位结果最好，尤其是在向上方向，而在模拟运动模式下，三个双频中频组合（FF3）模型的定位结果最大收敛时间的改进。