二进制偏移载波最小均方误差预滤波无模糊跟踪方法

摘要

A minimum mean square error criterion shaping (MMSES) method is proposed to solve the ambiguous tracking problem of binary offset carrier (BOO modulated signals used in global navigation satellite systems. An expression of the noise-term after correlation is derived through the analysis of the pre-filtering cost function. Then, the minimum mean square error criterion is used to get the optimal solution of the filter function with noise-term by optimizing the objective curve that is an unambiguous correlation function with narrow triangular shape. Finally, the shaping correlator is designed by using the pre-filtering structure. Simulation results show that the MMSES unambiguous tracking method gets a correlated function with single peak and 0. 2 X 10-6 s in width for BOC modulated signals of all kinds of phases and orders. When it is used to track high order BOC signal, the tracking error of the MMSES method is less over 50% than that of the BPSK-Like method in the carrier to noise ratio of 25-45 dB ? Hz, and the multipath error of the MMSES method is 0. 8 m smaller than that of the BPSK-Like method in the delay of 0-1. 5× 10-6 s.%针对全球导航卫星系统所使用的二进制偏移载波(BOC)调制信号存在跟踪模糊的问题,提出了一种最小均方误差预滤波(MMSES)无模糊跟踪方法.在分析预滤波代价函数的基础上,首先推导经过相关后的噪声功率项表达式,然后根据最小均方误差准则,以宽度较窄的三角形单峰无模糊相关函数为赋形目标,给出包含噪声项的滤波函数最优解,最后采用预滤波器结构设计出赋形相关器.仿真结果表明,MMSES无模糊跟踪方法能够适用于各种相位和阶数的BOC信号,得到主峰宽度为0.2×10-6 s的单峰相关函数,且在处理高阶调制信号时的跟踪误差在载噪比为25～45 dB,Hz范围内,比BPSK-Like方法减少了50％以上,多径误差在延时为0～1.5×10-6 s范围内比BPSK-Like方法减少0.8m.