高精度电离层产品增强PPP-B2b定位性能分析

Analysis of PPP-B2b Positioning Performance Enhanced by High-Precision Ionospheric Products

北斗三号卫星导航系统(BeiDou-3 satellite navigation system,BDS-3)通过PPP-B2b信号向中国及周边区域提供实时精密单点定位(precise point positioning,PPP)服务。由于PPP-B2b信号未提供电离层模型产品,目前的定位研究主要采用无电离层组合,其精度可以到达分米级,但是需要30 min左右的收敛时间。针对PPP-B2b定位收敛时间长的问题,分析了电离层模型产品对定位收敛性能的提升。将准四维电离层建模方法引入中国区域电离层延迟建模,并采用2021年年积日第201—207天中国区域均匀分布的50、100、150和200个基准站4种方案进行解算,结果表明,当电离层建模所用测站数量从50个增加至200个时,电离层模型产品精度从2~3 TECU提升至优于0.8 TECU。高精度电离层模型产品可以显著缩短PPP-B2b定位收敛时间,相比于目前PPP-B2b定位,基于电离层模型产品增强的单BDS-3动态PPP收敛时间仅需7.56 min,缩短77%;GPS+BDS-3双系统动态PPP收敛时间由13.51 min缩短至4.45 min。因此,高精度电离层模型产品能显著缩短PPP-B2b的定位收敛时间。

Objectives:The BeiDou-3 satellite navigation system(BDS-3)can provide real-time precise point positioning(PPP)services to China and neighboring regions through PPP-B2b signals.Because PPPB2b signals do not contain ionospheric model products,the current positioning research mainly adopts ionospheric-free combination.The positioning accuracy can reach decimeter level,but requires about 30 min of convergence time.In this paper,aiming at the long convergence time of PPP-B2b positioning,the improvement of positioning convergence performance based on ionospheric model products is analyzed.Methods:Quasi-4-dimensional ionospheric modeling is introduced into regional ionospheric delay modeling in China and four schemes of 50,100,150 and 200 reference stations uniformly distributed in China(day of year 201—207)are adopted for ionospheric modeling.Results:The results show that when the number of stations used in ionospheric modeling increases from 50 to 200,the accuracy of ionospheric model products increases from 2-3 TECU to better than 0.8 TECU.Compared with the current ionospheric-free combined PPP,the convergence time of BDS-3 dynamic PPP can be deceased by 77%.In addition,the convergence time of GPS+BDS-3 dynamic PPP is reduced from 13.51 min to 4.45 min.Conclusions:High-precision ionospheric model products can significantly shorten the convergence time of PPP-B2b.