基于地面监测网的多星精密定轨可以同时解算出北斗卫星轨道和卫星钟差。由于轨道和钟差的耦合影响,卫星钟差时序难免会出现周期性波动。此外,受限于目前并不完善的北斗全球监测网络分布、系统导航文件缺失以及定轨后处理软件的设置问题,3类卫星的钟差均存在大量数据间断问题。本文利用适用于间断数据的谱分析方法,对多星定轨条件下的北斗卫星钟差数据进行了周期项提取,并利用周期项改进后的钟差预报模型评估了24 h以内的预报精度。基于近一年的数据分析表明,北斗GEO卫星钟差3个主周期依次为12、24和8 h,IGSO卫星钟差的3个主周期依次为24、12和8 h,而MEO卫星钟差的3个主周期依次为12.91、6.44和24 h。与改进前相比,周期项改进后的钟差预报模型将北斗卫星钟差在24 h以内的预报精度提高了20%~40%。
Multi-satellite orbit determination based on global tracking network can generate satellite orbit and clock products for BDS at the same time. The errors in the two resulting products, however, are difficult to be decoupled completely. There might be periodic fluctuations existing in the satellite clock offsets. Restricted by current imperfect global tracking network, loses of navigation files and software settings, there exist a lot of data gaps in the BeiDou satellite orbit and clock products. A spectrum analysis method applicable to data with gaps was used, and the main periodic items of BeiDou satellite clock offsets were extracted with it. Two improved clock prediction models augmented with periodic corrections were proposed and the prediction accuracy within 24 hours was evaluated. The tested results with nearly one-year-long data showed that the three main periods in BeiDou GEO and IGSO satellite clock offsets are 12, 24 and 8 hours, respectively, while those for MEOs are 12.91, 6.44 and 24 hours. Compared with the conventional clock model of quadratic polynomial, the improved model can increase the prediction accuracy of BeiDou GEO and IGSO satellite clock offsets by 20 to 40 percent at spans less than 24 hours.
[1] GUO Hairong. Study on the Analysis Theories and Algorithms of the Time and Frequency Characterization for Atomic Clocks of Navigation Satellites[D]. Zhengzhou: Information Engineering University, 2006. (郭海荣. 导航卫星原子钟时频特性分析理论与方法研究[D]. 郑州: 信息工程大学, 2006.)
[2] GUO Hairong, YANG Yuanxi, HE Haibo, et al. Determination of Covariance Matrix of Kalman Filter Used for Time Prediction of Atomic Clocks of Navigation Satellites[J]. Acta Geodaetica et Cartographica Sinica, 2010, 39(2): 146-150. (郭海荣, 杨元喜, 何海波, 等. 导航卫星原子钟Kalman滤波中噪声方差-协方差的确定[J]. 测绘学报, 2010, 39(2): 146-150.)
[3] HUANG Guanwen. Research on Algorithm for Precise Clock Offset and Quality Evaluation of GNSS Satellite Clock[D]. Xi'an: Chang'an University, 2012. (黄观文. GNSS星载原子钟质量评价及精密钟差算法研究[D]. 西安: 长安大学, 2012.)
[4] SENIOR K L, RAY J R, BEARD R L. Characterization of Periodic Variations in the GPS Satellite Clocks[J]. GPS Solutions, 2008, 12(3): 211-225.
[5] WALLER P, GONZALEZ F, HAHN J, et al. In-orbit Performance Assessment of Giove Clocks[R]. Noordwijk: European Space Agency Noordwijk, 2008.
[6] MONTENBRUCK O,HUGENTOBLER U, DACH R, et al. Apparent Clock Variations of the Block IIF-1 (SVN62) GPS Satellite[J]. GPS Solutions, 2012, 16(3): 303-313.
[7] MONTENBRUCK O, STEIGENBERGER P, HUGENTOBLER U. Enhanced Solar Radiation Pressure Modeling for Galileo Satellites[J]. Journal of Geodesy, 2015, 89(3): 283-297.
[8] BROEDERBAUER V,OPITZ M,WEBER R.Automated Quasi-realtime Prediction of GNSS Clock Corrections[J]. Geophysical Research Abstracts, 2007, 9: 02964.
[9] ZHENG Zuoya, DANG Yaming, LU Xiushan, et al. Prediction Model with Periodic Item and Its Application to the Prediction of GPS Satellite Clock Bias[J]. Acta Astronomica Sinica, 2010, 51(1): 95-102. (郑作亚, 党亚民, 卢秀山, 等. 附有周期项的预报模型及其在GPS卫星钟差预报中的应用研究[J]. 天文学报, 2010, 51(1): 95-102.)
[10] HEO Y J, CHO J, HEO M B. Improving Prediction Accuracy of GPS Satellite Clocks with Periodic Variation Behaviour[J]. Measurement Science and Technology, 2010, 21(7): 073001.
[11] HUANG Guanwen, ZHANG Qin, XU Guochang, et al. IGS Precise Satellite Clock Model Fitting and Its Precision by Using Spectral Analysis Method[J]. Geomatics and Information Science of Wuhan University, 2008, 33(5): 496-499. (黄观文, 张勤, 许国昌, 等. 基于频谱分析的IGS精密星历卫星钟差精度分析研究[J]. 武汉大学学报: 信息科学版, 2008, 33(5): 496-499.)
[12] YANG Yuanxi. Progress, Contribution and Challenges of Compass/BeiDou Satellite Navigation System[J]. Acta Geodaetica et Cartographica Sinica, 2010, 39(1): 1-6. (杨元喜. 北斗卫星导航系统的进展、贡献与挑战[J]. 测绘学报, 2010, 39(1): 1-6.)
[13] LIU Weiping, HAO Jinming, LI Jianwen, et al. Multi-GNSS Joint Precise Orbit Determination of BeiDou Navigation Satellite System[J]. Acta Geodaetica et Cartographica Sinica, 2014, 43(11): 1132-1138. (刘伟平, 郝金明, 李建文, 等. 多GNSS融合的北斗卫星精密定轨[J]. 测绘学报, 2014, 43(11): 1132-1138.)
[14] MONTENBRUCK O, STEIGENBERGER P, KHACHIKYAN R, et al. IGS-MGEX: Preparing the Ground for Multi-constellation GNSS Science[C]//Proceedings of the 4th International Colloquium on Scientific and Fundamental Aspects of the Galileo System. Prague: ESA, 2013.
[15] YANG Yuanxi, LI Jinlong, WANG Aibing, et al. Preliminary Assessment of the Navigation and Positioning Performance of BeiDou Regional Navigation Satellite System[J]. Science China Earth Sciences, 2014, 57(1): 144-152.
[16] ZHOU Shanshi, HU Xiaogong, WU Bin, et al. Orbit Determination and Time Synchronization for a GEO/IGSO Satellite Navigation Constellation with Regional Tracking Network[J]. Science China Physics, Mechanics and Astronomy, 2011, 54(6): 1089-1097.
[17] ZHAO Qile, GUO Jing, LI Min, et al. Initial Results of Precise Orbit and Clock Determination for Compass Navigation Satellite System[J]. Journal of Geodesy, 2013, 87(5): 475-486.
[18] DENG Z, ZHAO Q, SPRINGER T, et al. Orbit and Clock Determination——BeiDou[C]//Proceedings of IGS Workshop. Pasadena: IGS, 2014.
[19] MAO Yue, DU Yu, SONG Xiaoyong, et al. GEO and IGSO Joint Precise Orbit Determination[J]. Science China Physics, Mechanics and Astronomy, 2011, 54(6): 1009-1013.
[20] STEIGENBERGER P, HUGENTOBLER U, HAUSCHILD A, et al. Orbit and Clock Analysis of Compass GEO and IGSO Satellites[J]. Journal of Geodesy, 2013, 87(6): 515-525.
[21] RILEY W J. User Manual: Stable32 Frequency Stability Analysis Version 1.5.0[M]. Beaufort, SC: Hamilton Technical Services, 2007.
[22] RILEY W J. Frequency Jump Detection in Stable32[M]. Beaufort, SC: Hamilton Technical Services, 2008.
[23] BARTOCCINI U, BARCHI G, NUNZI E. Methods and Tools for Frequency Jump Detection[C]//Proceedings of IEEE International Workshop on Advanced Methods for Uncertainty Estimation in Measurement, 2009. Bucharest: IEEE, 2009: 109-112.
