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基于Hadamard方差的导航星座自主时间同步算法研究

顾亚楠;陈忠贵;帅平;   

  1. 中国空间技术研究院;
  • 出版日期:2010-02-25 发布日期:2010-02-25

Autonomous Time Synchronization Algorithm on Hadamard Variance Among Navigation Satellites

Gu Yanan Chen Zhonggui Shuai Ping(China Academy of Space Technology,Beijing 100094)   

  • Online:2010-02-25 Published:2010-02-25
  • Supported by:
    国家863计划课题资助(2008AA12Z304)

摘要: 文章在总结国内外研究成果基础上,针对GPS铷钟虽然短期稳定性较好,但采用Allan方差描述铷钟频率稳定性时,其钟差状态方程仅为两参数,在较长平滑时间里存在时钟漂移和甚低频噪声的影响,使噪声特性淹没或估值不收敛的缺陷,引入Hadamard方差建立了三参数系统状态误差模型,通过三次采样方差从模型上解决了线形漂移和甚低频噪声的影响问题。在时钟系统状态模型和星间双向测量方程建模基础上,给出了工程实用的标准Kalman基本滤波方程。数值分析仿真表明,采用Hadamard方差描述时钟频率稳定性显著提高星载时钟自主同步精度,从而克服了Allan方差描述产生的频率漂移影响较大和甚低频噪声不收敛的问题。

关键词: 自主时间同步, 铷原子时钟, 钟差预报, Hadamard方差, 卡尔曼滤波

Abstract: High-accuracy auto-time synchronization is the foundation of the navigation constellation and a key technology of auto-navigation.The accuracy of time synchronization among navigation satellites is directly affected by frequency stability of on-board atomic clocks.GPS Rubidium atomic frequency standards(RAFS) exhibit non-trivial aging and aging noise characteristics,whereas the Allan variance does not explicitly converge for the noise type of α not more than-3),and can be greatly affected by frequency drift.The three-sample variance,commonly referred as a renormalized Hadamard variance was proposed,which was unaffected by linear frequency drift,converges for α more than-5),and thus can be used for modeling noise in Rubidium frequency standards.A standard Kalman filter algorithm based on improved clock error predication model and inter-satellites measurements equations was established for practical use in on-board RAFS.System simulation results show that more precise auto-time synchronization is achieved by this method.