导航辅助下基于LAS码的天基多目标测控

中继卫星的天基测控是解决中低轨道航天器大范围、长时间、多目标测控的有效途径,但用户星到中继卫星的时延误差、多普勒频移校正误差等参数会对多目标测控带来干扰。针对该问题,首先分析了定位误差引起的时延误差、多普勒频移校正误差等因素,设计了天基多目标前向链路遥控SMA(S-band Multiple Access,S频段多址)信号形式和反向遥测链路SMA信号形式,选择与时延校正误差相匹配的LAS(Large Area Synchronous,大区域同步)码作为反向遥测信息的扩频码,建立了导航辅助的终端时延和频率预校正方案模型,可以有效消除多用户干扰。仿真表明,当Eb/N0≥10.5dB时,前向遥控信息误码率pe≤1×10~(-6),反向遥测信息误码率pe≤1×10~(-6),使用LAS码比Gold序列约有2dB性能改善,为基于我国天链卫星的中低轨道卫星稳定运行、载人航天交会对接以及后续空间站建设等任务的测控提供重要参考。

Space-Based Multi-Object TT&C with Navigation Aids Based on LAS Code

With the rapid development of China's manned space flights,Beidou navigation and Low Earth Orbit (LEO) constellation system,Tracking and Data Relay Satellite (TDRS) provides a fundamental solution to solve the long time,high coverage and multi-satellites Tracking,Telemetry and Command (TT&C) problems for its space-based design thinking.In this process,parameters such as time delay of user satellites to relay satellites and correction error of Doppler frequency shift will bring interference to multi-object TT&C.In order to solve this problem,this paper analyzes factors such as time delay,Doppler frequency shift correction error due to positioning error,design S-band Multiple Access (SMA) signal form of forward link and reverse link based on the multi-object,choose Large Area Synchronous (LAS) code matching the time delay correction error as the spread spectrum code of the reverse telemetry information,and then proposes a navigation aided terminal delay and frequency pre-correction scheme model,which can eliminate multi-user interference effectively.Simulation results show when Eb/N0 of reverse link is more than 10.5 dB,the bit error rate of telemetry information is less than 1 × 10-6,which is economized 2 dB compared with Gold sequence.It provides an important reference to space-based TT&C for the stable operation of satellites in orbit,manned space rendezvous and docking and subsequent space station construction,etc.