基于自相关侧峰消除的北斗B1C快速高精度捕获算法  

Fast and high accurate acquisition algorithm of BeiDou B1C signal based on ASPeCT

作　　者：许睿[1] 唐瑞琪 罗凯 曾庆化[1] 刘建业[1] XU Rui;TANG Ruiqi;LUO Kai;ZENG Qinghua;LIU Jianye(College of Automation Engineering,Nanjing University of Aeronautics&Astronautics,Nanjing 211106,China)

机构地区：[1]南京航空航天大学自动化学院,南京211106

出　　处：《中国惯性技术学报》2021年第1期62-68,共7页Journal of Chinese Inertial Technology

基　　金：国家自然科学基金青年基金(61603181)。

摘　　要：北斗三号播发的B1C信号采用二进制偏移载波(BOC)调制方式和10 ms周期的伪随机码,可以与现存L1频段上的导航信号共有载波频率,同时提高导航信号的跟踪精度和伪距测量精度。然而,BOC调制会带来相关函数多峰性问题,10 ms周期的伪随机码会极大增加信号捕获的计算量,影响捕获速度,同时长码的跟踪需要更小带宽的跟踪环路,这对捕获精度提出更高要求。为此,根据北斗B1C信号的特点,在利用ASPeCT技术消除BOC信号相关副峰的基础上,兼顾捕获的快速性与精度,提出一种北斗BIC信号快速高精度捕获算法。所提算法先利用多级搜索和降采样策略快速实现信号的粗捕获,将捕获频率范围缩小,再利用多项式曲线拟合的方法进行多普勒频率精捕获,提高捕获精度。在多级搜索过程中,相关计算融合ASPeCT技术,通过本地码与副载波调制码构造无副峰相关函数,确保搜索过程无模糊度。所提捕获算法经接收前端采集的北斗B1C信号测试,实验表明,该捕获方法对相关副峰的消除程度可达到86.70%,多普勒频率误差缩小到1 Hz以内,捕获耗时相对缩短了近2/3,实现了快速高精度捕获,保障了后续跟踪算法的成功率。The B1C signal broadcasted by BeiDou-3 adopts BOC(binary offset carrier)modulation mode and pseudo-random code with 10 ms,which can share the same carrier frequency with the existing GPS signals at the L1 band and improve the tracking accuracy and pseudorange measurement accuracy of navigation signals.However,the BOC modulation brings about the multi-peak problem of correlation function.In addition,the long-period pseudo-random code increases the computation load and time in the acquisition process.The long-period code also makes the tracking loop adopt a narrow bandwidth which requires a high accurate initial value from the acquisition process.Therefore,according to the characteristics of Beidou B1C signals,a fast and high-precision BIC signal acquisition algorithm is proposed,on the basis of eliminating the correlation sub peaks of BOC signals by ASPeCT technology,and taking into account the rapidity and accuracy of the acquisition.The multistage search and down-sampling strategies are used to quickly capture the signal,and the range of capture frequency is reduced.Then,a polynomial curve fitting method is used to accurately capture the Doppler frequency to improve the capture accuracy.In the multi-stage search process,the correlation calculation is integrated with ASPeCT technology,and the correlation function without sub peak is constructed through local code and subcarrier modulation code to ensure the search process without ambiguity.The proposed algorithm is tested by collected BeiDou B1C signals.The experimental results show that the fast and high accurate acquisition method can eliminate the correlation sub peaks by 86.70%,reduce the error of Doppler frequency estimation less than 1 Hz,and shorten the acquisition time by near 2/3 relatively,which guarantees the success rate of the subsequent tracking algorithm.

关 键 词：北斗卫星导航系统 BOC调制 ASPeCT算法 快速捕获 精捕获 

分 类 号：U666.1[交通运输工程—船舶及航道工程]