北斗二号/三号融合的分米级星基增强算法与性能分析

北斗卫星导航系统星基增强服务通过地球静止卫星向用户播发等效钟差、轨道改正数、电离层格网改正数和分区综合改正数等四重广域差分改正数,用户在此基础上利用载波相位观测值实现实时分米级的定位性能.本文介绍了分米级星基增强服务的参数匹配算法以及单频、双频用户精密定位模型.将系统播发的四重差分改正数应用于北斗二号与三号融合的精密单点定位,分析了不同频点及定位模型的系统精密定位服务性能.18个测站7 d的结果表明:北斗二号/三号融合的星基增强服务双频组合动态精密单点定位平均12.42 min收敛至0.5 m以内,收敛后的平均定位精度为平面0.15 m,高程0.2 m;相比仅使用北斗二号系统,不同定位模型收敛时间平均缩短了56.7%;而基于非差非组合的分区定位收敛速度更快,并且能达到与无电离层组合模型相同的精度水平.使用北斗电离层格网信息改正的单频动态定位PPP平均11.74 min收敛至0.8 m以内,收敛后的平均定位精度为平面0.2 m,高程0.3 m;相比使用广播星历电离层模型改正的结果,静态和动态定位平均收敛时间分别缩减了21.4%和25.2%.

Decimeter-level algorithm for satellite-based augmentation systems and performance analysis of BDS-2/BDS-3

BeiDou navigation satellite systems and satellite-based augmentation systems(BDS-SBAS)broadcast various wide-area differential corrections,including satellite orbit/clock corrections,ionospheric grids,and partition comprehensive corrections,through geostationary earth orbit(GEO)satellites.Users in the BDS GEO coverage areas can achieve decimeter-level positioning in real time.Based on the positioning parameters and carrier-phase observations,this paper introduces matching algorithms for BDS-SBAS differential corrections and related precise point positioning(PPP)models.Datasets were collected from 18 stations over 7 d in 2020 and were analyzed by PPP in BDS-2 only and combined BDS-2/BDS-3 scenarios.The convergence time was significantly shorter in the combined BDS-2/BDS-3 scenario than in the BDS-2 only scenario,owing to the larger number of satellites and the optimized constellation geometry in the combined case.In the BDS-2/BDS-3 combination,the dual-frequency kinematic PPP converged to 0.5 m in 12.42 min(on average),56.7%shorter than in the BDS-2 only scenario,and the horizontal and height positioning accuracies after convergence were 0.15 and 0.2 m,respectively.Moreover,the un-differenced and un-combined model converged faster than the ionosphere-free combination model while achieving the same accuracy.Meanwhile,the singlefrequency kinematic PPP with ionospheric grid corrections converged to 0.8 m in 11.74 min,and the horizontal and height positioning accuracies after convergence were 0.2 and 0.3 m,respectively.Relative to the broadcast ionospheric model,the ionospheric grids reduce the convergence time of single-frequency static and kinematic PPP by 21.4%and 25.2%,respectively.