高轨微弱信号的跟踪算法分析及仿真

Analysis and Simulation of Tracking Algorithm for High Orbit Weak Signal

高轨航天器自主导航技术是中国迫切需要发展的航天新技术之一,广泛应用于通信、导航、气象、预警等领域。高轨导航接收机为高轨航天器自主导航定位提供了便捷有效的手段。在高动态环境下,载波频率和相位、伪码相位均随载体运动发生较大变化。由于载体动态引入的多普勒频率变化对伪码跟踪环的影响可通过载波辅助消除,接收机的动态性能主要取决于载波跟踪模块的性能。高轨高动态信号由于传播路径的增加,导致高轨导航接收机出现接收信号路径损耗大和信号微弱的问题。通过开展高轨弱信号跟踪技术专项研究及多次仿真分析、合理设计环路噪声带宽和调整预检积分时间等措施,能够有效稳定地处理跟踪–173 dBw导航弱信号。该技术成功应用于嫦娥五号卫星,并为后期高轨卫星导航、绕月飞行等深空探测项目提供技术指导和指标参考。

Autonomous Navigation Technology of high orbit spacecraft is one of the new aerospace techniques to be developed urgently in China, which is widely used in communication navigation,meteorology, early warning and other fields. High orbit navigation receiver provides a convenient and effective means for autonomous navigation and positioning of high orbit spacecraft. In the high dynamic environment, the carrier frequency, phase and pseudo code phase change greatly with the carrier motion.Because the influence of Doppler frequency change introduced by carrier dynamics on PN code tracking loop can be eliminated by carrier assistance, the dynamic performance of receiver mainly depends on the performance of carrier tracking module. The increase of propagation path of high orbit, high dynamic signal leads to the problems of large loss of received signal path and weak signal of high orbit navigation receiver. Through carrying out special research on high orbit weak signal tracking technology, through many times of simulation and analysis, through reasonable design of loop noise bandwidth and adjustment of pre-integration time and other measures, it can effectively and stably process and track the navigation weak signal of –173 dBw. The algorithm has been applied to the Chang’E-5 high orbit navigation receiver project. It provides the technical guidance and index reference for later engineering application such as flying around the Moon.