一种新的二进制偏移载波调制信号无模糊度捕获算法

New unambiguous acquisition algorithm for binary offset carrier modulated signal

二进制偏移载波(BOC,Binary Offset Carrier)调制有效地解决了导航信号间的相互干扰,实现了频谱资源的有效利用。针对BOC信号的自相关函数在±1码片内存在多个正负峰,易造成误捕旁峰和漏捕信号的风险,通过分析了BOC信号中单个码片内调制的矩形脉冲之间的周期延拓关系,确定一个基准单元,将BOC信号可分离成基准单元和基准单元经一系列周期延拓后相加,基于此实现BOC信号自相关函数的分离。根据对称性,可重构一个峰值较低单峰,基于产生的单峰与BOC信号自相关函数相乘即可消除多峰并提高中心主峰峰值。BOCs(2,1)、BOCs(3,2)和BOCc(2,1)信号仿真结果表明,该方法能完全消除信号的旁峰,适用于任意阶数的正弦或余弦相位BOC信号的捕获,而且保留了BOC信号窄相关峰特性,峰宽度为1/k个码片。

Binary offset carrier(BOC) modulation can effectively solve the mutual interference between navigation signals, and realize the effective use of spectrum resources. However, BOC signal's autocorrelation function has multiple positive and negative peaks within ±1chip, which leads to error acquisition and lost acquisition. To solve this problem, the periodic extension among the modulated rectangular pulses in each spread spectrum code chip are analyzed, and a base unit is determined to separate the BOC signals into a base unit and a combined unit which superimposed a series of periodic extended base units, and thus realize the separation of BOC signal's autocorrelation function. According to the symmetry, a low single correlation function is reconstructed, which can not only remove side peak, but also increase the value of center main peak by means of single peak multiplied with BOC single's autocorrelation function. The results show that the proposed method can remove side-peaks of BOCs(2,1), BOCs(3,2), and BOCc(2,1) signal, and therefore can be applied to any order of sine or cosine phase BOC signal acquisition. Moreover, it reserves BOC signal's the features of narrow correlation peak, and the width is 1/k chip.