Abstract For precise position services, the real-time precise point positioning (PPP) is a promising technology. The real-time PPP performance is expected to be improved by multi-system combination. The performance of real-time multi-system PPP needs to be periodically investigated, with the increasing number of available satellites and the continuously improved quality of real-time precise products of satellite clocks and orbits. In this study, a comprehensive performance assessment is conducted for the four-system integrated real-time PPP (FSIRT-PPP) with GPS, BDS, Galileo and GLONASS in both static and kinematic modes. The datasets from 118 stations spanning approximately a month are used for analysis, and the real-time stream CLK93 is employed. The superior performance of FSIRT-PPP is validated by comparing with the results of GPS/BDS, GPS/Galileo, GPS/GLONASS, GPS-only, BDS-only, Galileo-only and GLONASS-only cases. The FSIRT-PPP using ionospheric-free (IF) combined observables can achieve a convergence time of 10.9, 4.8 and 11.8 min and a positioning accuracy of 0.4, 0.5 and 0.7 cm in the static mode in the east, north and up directions, respectively, while the derived statistic is 15.4, 7.0 and 16.4 min, and 1.6, 1.2 and 3.4 cm in the kinematic mode in the three directions, respectively. Moreover, we also compare the position solutions of real-time PPP adopting IF combined and uncombined (UC) observables, and prove the mathematical equivalence between the two PPP models in the converged stage, provided that there are no external ionospheric corrections or constraints given to the estimated ionospheric delays in the UC model. The difference between the fully converged positioning accuracy of IF-based and UC-based real-time PPP is marginal, but the UC-based real-time PPP has longer convergence time due to the influence of the significant unmodeled time-varying errors in the real-time precise products as well as the different parameterization between them. For completeness, the real-time kinematic PPP results in harsh environments and the post-processed PPP results are also presented.

中文翻译：

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实时多 GNSS 集成 PPP 与未组合和无电离层组合可观测物的性能评估

摘要 对于精确定位服务，实时精确点定位（PPP）是一种很有前途的技术。多系统组合有望提高实时PPP性能。随着可用卫星数量的不断增加和卫星钟轨实时精密产品质量的不断提高，实时多系统PPP的性能需要定期进行研究。在这项研究中，对具有 GPS、BDS、Galileo 和 GLONASS 的四系统集成实时 PPP（FSIRT-PPP）在静态和运动模式下进行了综合性能评估。使用来自 118 个站点大约一个月的数据集进行分析，并采用实时流 CLK93。通过与 GPS/BDS 的结果对比，验证了 FSIRT-PPP 的优越性能，GPS/Galileo、GPS/GLONASS、仅 GPS、仅 BDS、仅 Galileo 和仅 GLONASS 情况。FSIRT-PPP使用无电离层（IF）组合可观测物在东、北和上方向的静态模式下收敛时间分别为10.9、4.8和11.8分钟，定位精度分别为0.4、0.5和0.7厘米，而导出的统计量分别为 15.4、7.0 和 16.4 分钟，在三个方向的运动模式下分别为 1.6、1.2 和 3.4 厘米。此外，我们还比较了采用 IF 组合和未组合 (UC) 可观测量的实时 PPP 的位置解，并证明了收敛阶段两个 PPP 模型之间的数学等价性，前提是没有外部电离层校正或约束UC 模型中估计的电离层延迟。基于 IF 和基于 UC 的实时 PPP 的完全收敛定位精度之间的差异很小，但基于 UC 的实时 PPP 的收敛时间更长，因为在实时精确产品以及它们之间的不同参数化。为完整起见，还提供了恶劣环境下的实时动态 PPP 结果和后处理的 PPP 结果。