GALILEO接收机中BOC(1,1)信号的捕获

BOC(1,1)(Binary-Offset-Carrier)信号相关函数中的零值会使接收机判定没有捕获到信号.为了完全捕获到BOC(1,1)信号,从副载波相位和码相位角度出发,提出了一种3路并行捕获方法.通过数字仿真得到了BOC(1,1)和扩频码的相关函数图,比较了二者相关函数的峰值.推导了BOC(1,1)相关函数的解析式,给出了相关函数中的零点位置和峰值位置,比较了BOC(1,1)和扩频码的相关函数数值及捕获.3路本地BOC信号以其中一路相位为基准,另外2路相位分别超前、滞后该路.给出了3路本地信号的生成方法及捕获的结构框图.仿真结果表明,捕获码相位差在半个码片内时,BOC(1,1)信号的捕获率从33.3%提高到100％,码相位捕获范围从1/6码片增大到1/2码片.该方法可为跟踪环路提供相位信息,适用于BOC(n,n)信号的捕获. 

Acquisition for BOC (1,1) signal in GALILEO receiver

The zero values in BOC(1,1)(binary-offset-carrier) signal correlation function could make the receiver judge that the signal was not acquired.From the sub-carrier phase and code phase viewpoint,an acquisition method with three parallel tags was proposed to acquire the BOC(1,1) completely.The BOC(1,1) and its spread code correlation function figure were drawn by digital simulation,and the correlation function peaks were compared.The analytic formula for BOC(1,1) autocorrelation function was deduced,the position for peak values and zero values were shown.The correlation function values and acquisition were compared between BOC(1,1) and its spread code.The phase in one tag served as benchmark,the other two tags phases were respectively earlier or later than the benchmark in three local(BOC(1,1)) signals.The generation method for three local(BOC(1,1)) signals and the acquisition method figure were shown.When the difference of code phase between the received and the local(BOC(1,1)) signal lies in the half code chip,the signal acquisition rate increases from 33.3% to 100%,and the code phase range increases from 1/6 to 1/2 chip width by simulation.The method can provide phase information to the track loop and adapt to acquisition for BOC(n,n) signal.