面向高轨航天器的北斗导航特性分析

Characteristics Analysis of Beidou Navigation Signal Based on High Orbit Spacecraft

利用卫星导航信号实现高轨航天器的自主定轨与导航已成为当前国内外的研究热点,高轨星载导航接收机面临可见卫星数少、接收导航信号微弱、动态性较大等问题。针对以上问题,分析了高轨环境下星载导航接收机获取到的信号功率、可见星数、DOP值及多普勒频移状态。首先建立了北斗星座模型与高轨航天器动力学模型,构建星间测距链路,对高轨卫星的可见性进行了仿真分析,结果表明当星载接收机功率为-177 dBw时,可见星数能达到4颗以上,能满足定轨需求;然后对高轨卫星的定轨精度进行了仿真,DOP值的均值为15.6578;最后对导航卫星和高轨卫星之间的多普勒频移进行了分析,仿真的多普勒范围为±14 kHz。相关研究结果可支撑高轨航天器星载接收机的开发。

With the development of satellite navigation technology and the maturity of satellite navigation receiver,the application of satellite navigation receiver to autonomous navigation of high orbit spacecraft has gradually become the focus of research at home and abroad.The high orbit satellite borne navigation receivers are confronted with such problems as less visible satellites,weak navigation signals and larger dynamic characteristics.In view of the above problems,the navigation signal power,visible star number,DOP value and Doppler frequency shift received by satellite borne navigation receivers in high orbit environment are analyzed.First,the Big Dipper model is established according to the ephemeris,dynamics model construction of high orbit spacecraft,build inter satellite communication link,visibility of high orbit satellite are simulated and analyzed,the results show that when the satellite receiver power is-177 dBw,the number of visible satellites can reach more than four,can meet the demand of the orbit;then high orbit satellite orbit accuracy simulation,the orbit accuracy than the ground precision high orbit satellite receiver,this is due to the high orbit visible stars attract less;finally between navigation satellite and high orbit satellite Doppler simulation,Doppler simulation range is±14 kHz.The research provides the theoretical basis and data support for the following weak signal acquisition and tracking.