优化组合相关函数方法的BOC无模糊跟踪性能研究

Unambiguous tracking Performance Research for BOC Signals Based on Optimizing Combined Correlation Function Method

摘要:

二进制偏移载波(Binary-Offset-Carrier)调制广泛应用于现代化的全球导航卫星系统(Global Navigation Satellite System, GNSS)中,但BOC信号的自相关函数(Autocorrelation Function, ACF)的多副峰性质易产生跟踪模糊。针对该问题,提出了一种基于优化组合相关函数方法来实现BOC信号无模糊跟踪。该方法以自相关函数主峰为无模糊跟踪目标函数,采用最小二乘法获得多组不同时延BOC信号自相关函数组合的加权系数,并将获得的无模糊相关函数与原自相关函数相乘构成非相干鉴相器实现无模糊跟踪。分析了正弦相位和余弦相位BOC信号的跟踪性能,仿真结果表明该方法消除了BOC信号的跟踪模糊,同时保持了良好的跟踪性能。

Abstract:

Binary-Offset-Carrier (BOC) modulation is widely applied in the modernized global navigation satellite system (GNSS). However, ambiguity may be generated in the code tracking loop due to the multiple side-peaks in the BOC autocorrelation function (ACF). Aiming at this problem, an unambiguous tracking method based on optimizing combined correlation function for BOC signals is proposed. This technique set the main-peak of the BOC ACF as the unambiguous target function, then use the least square method to obtain weighted coefficients of combined ACF for BOC signals with multiple different delays. And a new non-coherent discriminator function that the obtained unambiguous correlation function multiplied by the primary ACF of BOC signals is employed to achieve unambiguous tracking. The tracking performance for both sin-phased BOC and cosine-phased BOC signals is analyzed. Simulations show that the proposed method can solve the ambiguity problem for BOC signals completely and maintain good accuracy in the tracking loop.