伽利略系统BOC信号的特性及码跟踪方法研究

为了节省卫星频率资源并提高导航信号的可靠性,新一代的导航定位系统采用了一种更有效的调制方式-BOC调制,它具有与BPSK之间串扰小、抗衰落能力强等诸多优点.但由于BOC调制信号特性比较复杂,因此加大了接收处理的难度.本文主要从理论上介绍了BOC和Alt-BOC的调制方式和信号产生方法、调制后信号的频谱特性以及自相关函数特性,依此分析了BOC信号自相关结果的多峰值特性和由此特性造成的跟踪和锁定难度的增加,以及相应于其频谱特性栽的信号处理方法.并在此基础上提出了一种能提高码跟踪可靠性的基带信号相关处理方法,Matlab仿真结果表明此方法有较好的效果,能提高码跟踪的可靠性.

Characteristics of GNSS BOC modulation signal and code tracking technique

With an aim to save the satellite frequency resource and the reliability of navigation signal,a novel signal modulating method,Binary Offset Carrier(BOC) modulation,was adopted in modern satellite navigation system.BOC modulation has the advantages of little crosstalk with BPSK and high anti-fading capability.Since the spectrum characteristics of BOC modulation signal is rather complicated,it can increase the difficulty in signal processing.The author presented the modulating mode,signal generating method,spectrum density of modulated signal,and autocorrelation characteristics of BOC modulation,as well as AltBOC modulation which will be used in SoL service.On which basis,the characteristics of BOC signal and the increased difficulty in tracking and locking on resulted from that were analyzed,the corresponding signal processing method adapted to the spectrum characteristics was put forward.Then,a method for baseband signal processing is put forward,which can improve code tracking reliability.Simulation result proved the effect of the method.