中文摘要：

GNSS精密单点定位技术因其只采用单台接收机就能获得高精度的定位结果而成为近年来的研究热点。精密单点定位通常采用3种模型：无电离层组合模型、Uofc模型与非组合模型。本文从模糊度固定的角度详细论述了这3种模型的相互关系,公式推导证明了非组合模型与Uofc模型等价,且都优于无电离层组合模型;与采用等价性原理消去电离层延迟的Uofc模型相比,非组合模型将电离层延迟作为参数求解,能为用户提供附加电离层先验约束的条件,从而方便地转换为电离层加权模型。在固定宽巷模糊度的情况下,采用模糊度精度因子（ADOP）对模糊度的固定效率进行了分析,验证了Uofc模型相对于无电离层组合模型具有噪声小、不损失原始观测信息等优点。而附电离层约束的非组合模型在高精度先验电离层信息约束下能有效提高模糊度固定效率。

英文摘要：

GNSS precise point positioning （PPP） has become the research hotspot in the most recent years due to its capability of obtaining precise position with single receiver. Usually, three models are used in PPP, that is, uncombined model, Uofc model and ionosphere-free combination model. The relationships between the these models are described in detail in this paper. On the one hand, it is clarified that the uncombined model is equivalent to the Uofc model and both of them are better than the ionosphere-free model in the sense of ambiguity resolution. On the other hand, in comparison with the Uofc model that eliminates the ionosphere delay by using the equivalence principle, the uncombined model that takes the ionosphere delay as the parameter has its advantage that it can provide the users with the prior constrained conditions for the ionosphere. As a result, the model can be converted to the ionosphere- weighted model easily, In the circumstance of fixing the wide-lane, when comparing with the ionosphere- free model by using ambiguity dilution of precision （ADOP） from the aspect of fixing ambiguity, Uofc model has many advantages such as small noise, origin information preserving etc.,while the ionosphere-weighted model can improve the ambiguity resolution significantly when the high precise prior ionosphere information is available.