基于CNES实时产品的精密单点定位性能评估

Performance evaluation of precise point positioning based on CNES real-time products

关键词:  精密单点定位  模糊度固定  实时精密产品  非差非组合  无电离层组合

Key words:  Precise point positioning  Ambiguity resolution  Real-time precise products  Undifferenced and uncombined  Ionosphere-free combination

摘要:

实时精密单点定位(PPP)技术是全球卫星导航系统(GNSS)技术发展的重要方向。为进一步推动实时PPP技术的应用，考虑到法国国家空间研究中心(CNES)是全球领先的实时产品播发机构，从轨道和钟差产品精度、观测值偏差(OSB)产品数据可用率和模糊度残差、定位精度及收敛时间等方面，综合分析了CNES实时精密产品的质量及精密单点定位模糊度固定(PPP-AR)的定位性能。同时，提出了利用一次多项式进行拟合推估，解决了短期OSB产品中断的问题。实验结果表明：GPS/Galileo/BDS的轨道和钟差产品精度分别为3 cm，5 cm，13 cm和0.10 ns，0.13 ns，0.34 ns;宽巷模糊度残差在±0.25周以内的百分比分别为97.36%，95.67%，81.05%，而窄巷为88.01%，88.63%，75.38%。与GPS和Galileo相比，BDS的实时产品质量较差，限制了其提供的定位服务。在PPP-AR定位性能方面，与无电离层组合模型相比，非差非组合PPP的性能提升较为显著。GPS和Galileo双系统动态非差非组合PPP-AR定位误差在东、北及天顶方向分别为1.45 cm，1.51 cm，4.16 cm，模糊度固定率约为97%，收敛时间比PPP缩短了37%以上。最后，采用一次多项式模型推估缺失的OSB产品，可提高实时PPP-AR定位的稳定性和可靠性。

Abstract:

Real-time precise point positioning (PPP) is an important direction for the development of GNSS technology. In order to further promote the application of real-time PPP technology, considering that the Centre National D‘études Spatiales (CNES) is a leading real-time product broadcasting organization around the world, and the quality of CNES real-time precise products and the positioning performance of PPP-ambiguity resolution (PPP-AR) are synthetically analyzed based on aspects including orbit and clock error product accuracy, observable-specific bias (OSB) product data availability and ambiguity residuals, positioning accuracy, and convergence time. Meanwhile, the problem of short-term OSB product interruption is solved using polynomial fitting and estimation. The experimental results show that the accuracy of GPS/Galileo/BDS orbit and clock products are 3 cm, 5 cm and 13 cm, and 0.10 ns, 0.13 ns and 0.34 ns, respectively. And the percentages of wide-lane ambiguity residuals within ±0.25 cycles are 97.36%, 95.67%, and 81.05%, respectively, while the percentages of narrow-lane ambiguity residuals within ±0.25 cycles are 88.01%, 88.63%, and 75.38%. Compared to GPS and Galileo, the real-time product of BDS is of poor quality, which limits the positioning services it provides. In terms of PPP-AR positioning performance, undifferenced and uncombined PPP shows significant improvements over the ionosphere-free combination model. The kinematic undifferenced and uncombined PPP-AR positioning errors of the GPS and Galileo dual systems are 1.45 cm, 1.51 cm and 4.16 cm in the east, north and up directions, respectively, with an ambiguity resolution success rate of about 97%, and the convergence time is reduced by more than 37% compared to PPP. Finally, the OSB product estimated by a polynomial model can improve the stability and reliability of real-time PPP-AR positioning.