GALILEO接收机中BOC(1,1)信号的捕获

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

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.

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（I, 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.