余弦BOC信号伪相关函数无模糊跟踪方法

Unambiguous Tracking Method for Cosine-phased BOC Signals Based on Pseudo Correlation Function Method

摘要:

二进制偏移载波 (binary offset carrier,BOC) 调制方式实现了频谱分离和频段共享,被应用于全球导航卫星系统中；但由于BOC信号自相关函数的主峰和副峰幅度差异较小,容易引起捕获和跟踪模糊,导致较大的测距误差;余弦相位BOC(Cosine-phased BOC,CosBOC)信号自相关函数形式相对复杂,给其无模糊处理带来了挑战;基于伪相关函数法(pseudo correlation function, PCF)思想,针对CosBOC信号设计本地参考信号的特殊码片波形,与接收信号相关后经过非线性组合可获得单峰无模糊相关函数,消除了跟踪模糊性;仿真结果表明:参数取值合适时该方法的跟踪和抗多径性能均优于同等条件下的BPSK-like方法。

Abstract:

Binary offset carrier (BOC) signals commonly used in global navigation satellite system because it can guarantee the coexistence and interoperability with different systems, while it usually causes ambiguity problems and range measurement errors due to the similar magnitude multiple side peaks of the autocorrelation function. The autocorrelation function of the Cosine-phased binary offset carrier (CosBOC) is relatively complicated and brings challenge in the unambiguous tracking. Based on the concept of pseudo correlation function (PCF), this paper proposes specially designed chip spreading symbols of the local reference signals for CosBOC signals. After correlating with the received signal and nonlinear processing, a no side-peak function can be obtained and the ambiguity is eliminated. Results demonstrate that the code tracking and multipath mitigation performances of the proposed method are better than the BPSK -like method on the whole.