全球参考站网窄巷非校准相位延迟

窄巷非校准相位延迟（UPD）产品的质量和可用性是影响精密单点定位模糊度固定（PPPAR）效率的重要因素.采用全球108个国际GPS服务（International GPS Service，IGS）测站观测数据，计算了基于全球参考站网的窄巷UPD产品，分析了窄巷UPD产品的变化特性，其单日变化量最大可达0.6周.通过分析UPD改正后的模糊度残差，论证了UPD产品和用户端模糊度均受到因未被恰当模型化而造成的残余误差的影响，且UPD的时变特性与各参考站残余系统误差有关.最后，采用4个用户站进行PPPAR实验分析UPD产品的可用性，以模糊度固定失败率、固定错误率和首次固定时间为评估指标，结果表明，全球参考站网窄巷UPD产品的最佳使用时限不大于30 min.

Time varying Property of Narrowlane Uncalibrated Phase Delays Products Estimated from a Global Reference Station Network

The quality and availability of narrowlane (NL) uncalibrated phase delays (UPD) products are the key factors to precise point positioning ambiguity resolution (PPP AR) service. In this paper, the GPS observations from 108 world distributed International GPS Service (IGS) reference stations were employed to calculate the widelane (WL) and NL UPD products. The variations of NL UPDs were evaluated and the results show that the maximum daily variation can reach 0.6 cycles. Then, the residuals of ambiguities corrected with UPDs were analyzed to demonstrate that ambiguities and UPDs are both influenced by the unmodeled atmosphere errors. We found the time varying property of NL UPD is relevant to the residual atmospheric errors of the selected reference stations used to estimate UPDs. Moreover, the real observation data of four IGS stations were processed in PPPAR mode to demonstrate the time availability of UPD products. The statistical results of time to first fix (TTFF), unfix rate and incorrect fix rate were adopted to evaluate the performance of PPPAR service. According to the experiment results, we concluded that the effective time limit of NL UPD products should be no more than 30 minutes.