不同电离层改正的PPP时间传递性能评估

Performance evaluation of PPP time transfer by different ionospheric correction strategies

为了进一步验证全球卫星导航系统(GNSS)电离层参数化模型及不同精度电离层改正产品在非差非组合精密单点定位(PPP)时间传递中的应用效果,提出一种不同电离层改正的PPP时间传递性能评估方法:分析比较无电离层组合PPP(IF-PPP)和非差非组合PPP(UDUC-PPP)时间传递模型与接收机钟差参数的差异;然后基于2020年年积日第11—31天欧洲永久跟踪站网数据进行实测数据验证,并选择其中202个跟踪站构建区域电离层格网图(RIM),比较全球电离层格网图(GIM)非差非组合PPP(GIM-PPP)及区域电离层格网图非差非组合PPP(RIM-PPP),基于5个外接氢钟的欧洲永久跟踪站网接收机实现进一步的PPP时间传递性能分析。结果表明,与传统IF-PPP模型相比,GIM-PPP和RIM-PPP模型PPP单向授时精度分别平均提高24%、44%,对于时间传递,IF-PPP、GIM-PPP和RIM-PPP模型重叠阿伦(Allan)方差百秒稳和千秒稳分别为9.36×10^(-14)、7.88×10^(-14)、5.11×10^(-14)和1.98×10^(-14)、1.78×10^(-14)、1.24×10^(-14);表明UDUC-PPP模型时间传递稳定性明显优于IF-PPP模型,而得益于高精度电离层模型,RIM-PPP可进一步提升GIM-PPP时间传递稳定性。

In order to further verify the deterministic plus stochastic ionospheric delay modeling for global navigation satellite system(GNSS)and the application effect of ionospheric correction products with different precision in non-differential and non-combination precise point positioning(PPP)time transfer,the paper proposed a performance evaluation method of PPP time transfer by different ionospheric correction strategies:the difference between the time transfer model and the receiver clock parameters of ionosphere-free PPP(IF-PPP)and undifferenced and uncombined PPP(UDUC-PPP)was comparatively analyzed;in addition,the data of European Permanent Tracking Network(EPN)from day of year(DOY)11-31,2020 were collected for the experimental evaluation,and 202 stations were selected to construct the regional ionosphere map(RIM),and the global ionosphere map(GIM)UDUC-PPP(GIM-PPP)and the regional ionosphere map UDUC-PPP(RIM-PPP)were further compared,futhermore,analyzing PPP time transfer performance was conducted with 5 EPN station network receivers equipped with an external hydrogen clock.Results showed that compared with the traditional IF-PPP model,the precision of one-way time service of GIM-PPP and RIM-PPP models could be improved by 24%and 44%,respectively,and for time transfer,IF-PPP,GIM-PPP and RIM-PPP would overlapp Allan variance with a 100-second stability and a 1000-second stability of 9.36×10^(-14),7.88×10^(-14),5.11×10^(-14)and 1.98×10^(-14),1.78×10^(-14),1.24×10^(-14),respectively,indicating that the time transfer stability of UDUC-PPP model would be significantly better than that of IF-PPP model,and RIM-PPP could further improve the time transfer stability of GIM-PPP benefiting by the high-precision ionosphere model.