NH码对新一代GNSS信号捕获跟踪的影响  

Effects of NH Code for BeiDou Signal Acquisition and Tracking

作　　者：严昆仑[1] 章红平[1] 张提升[1] 牛小骥[1] 

机构地区：[1]武汉大学卫星导航定位技术研究中心,湖北武汉430079

出　　处：《武汉大学学报（信息科学版）》2015年第5期682-687,共6页Geomatics and Information Science of Wuhan University

基　　金：国家自然科学基金资助项目(41174028);国家863计划资助项目(2012AA12A206);中国科学院开放基金资助项目(2012PNTT10)~~

摘　　要：针对传统跟踪环路在跟踪调制有NH码的GNSS信号时性能下降的问题,在建立接收信号模型的基础上,推导了积分清零电路中积分幅值的概率密度函数,通过分析频率误差与积分幅值的关系,对NH码调制造成的跟踪性能下降的原因进行了研究,结论表明,调制有NH码的GNSS跟踪要求信号捕获得到的多谱勒频率偏差更小。通过软硬件接收机对常用的鉴频器进行了测试,结果表明,频率误差较大时二象限鉴频器无法锁定,四象限鉴频会导致频率误锁,而精细捕获后采用二象限鉴频能正确跟踪信号,与理论分析一致。Aiming at the problem that the traditional tracking loop may have performance degradation when tracking GNSS signals with NH code, we deduce the probability density function of integral am- plitude in the accumulate-dump circuit on the basis of constructing the signal models, and conduct an intensive study on the reasons of performance degradation caused by NH code modulation. The result indicates that GNSS signals tracking with NH code requires smaller Doppler frequency residual in ac- quisition. On this basis, we conduct a testing experiment on the common frequency discriminators by the software and hardware receivers. The results show that the two-quadrant discriminator can＇t lock when the frequency residual is big, and the four-quadrant discriminator will lock at the wrong frequen- cy. However, the signals can be tracked correctly adopting the two-quadrant discriminator after fine acquisition, which is consistent with the theoretical analysis.

关 键 词：NH码 四象限鉴频 积分幅值 精细捕获 

分 类 号：P228.41[天文地球—大地测量学与测量工程]