Geng Tao, Zhang Peng, Wang Wei, Xie Xin
GNSS Research Center, Wuhan University, No.129 Luoyu Road, Wuhan 430079, China.
Collaborative Innovation Center of Geospatial Technology, No.129 Luoyu Road, Wuhan 430079, China.
Sensors (Basel). 2018 Feb 6;18(2):477. doi: 10.3390/s18020477.
Currently, ultra-rapid orbits play an important role in the high-speed development of global navigation satellite system (GNSS) real-time applications. This contribution focuses on the impact of the fitting arc length of observed orbits and solar radiation pressure (SRP) on the orbit prediction performance for GPS, GLONASS, Galileo and BeiDou. One full year's precise ephemerides during 2015 were used as fitted observed orbits and then as references to be compared with predicted orbits, together with known earth rotation parameters. The full nine-parameter Empirical Center for Orbit Determination in Europe (CODE) Orbit Model (ECOM) and its reduced version were chosen in our study. The arc lengths of observed fitted orbits that showed the smallest weighted root mean squares (WRMSs) and medians of the orbit differences after a Helmert transformation fell between 40 and 45 h for GPS and GLONASS and between 42 and 48 h for Galileo, while the WRMS values and medians become flat after a 42 h arc length for BeiDou. The stability of the Helmert transformation and SRP parameters also confirmed the similar optimal arc lengths. The range around 42-45 h is suggested to be the optimal arc length interval of the fitted observed orbits for the multi-GNSS joint solution of ultra-rapid orbits.
目前，超快速轨道在全球导航卫星系统（GNSS）实时应用的高速发展中发挥着重要作用。本文着重研究观测轨道的拟合弧长和太阳辐射压力（SRP）对GPS、GLONASS、伽利略和北斗轨道预测性能的影响。将2015年一整年的精密星历用作拟合观测轨道，然后作为参考与预测轨道进行比较，并结合已知的地球自转参数。本研究选用了完整的九参数欧洲定轨经验中心（CODE）轨道模型（ECOM）及其简化版本。经赫尔默特变换后，轨道差异的加权均方根（WRMS）和中位数最小的观测拟合轨道弧长，对于GPS和GLONASS而言在40至45小时之间，对于伽利略系统在42至48小时之间，而对于北斗系统，在42小时弧长之后WRMS值和中位数趋于平稳。赫尔默特变换和SRP参数的稳定性也证实了类似的最佳弧长。建议42 - 45小时左右的范围为超快速轨道多GNSS联合解算中观测拟合轨道的最佳弧长时间间隔。
