导航卫星伪码与载波测距观测量偏差机理分析

Research on Mechanism of Divergences Between Code Pseudorange and Carrier Phase Observations of Navigation Satellite

伪码测距和载波相位测距是卫星无线电导航系统定位、导航与授时(PNT)服务的两个基本观测量,文章针对国外文献所描述的北斗区域系统卫星在轨伪码测距测量值与载波相位观测量出现偏差,并且偏差随用户仰角发生规律性变化的异常现象,用伪码测距测量偏差的方法开展了机理分析,建立了多径效应评估的数学模型。仿真结果表明:导航卫星有效载荷各天线阵元之间时延不一致会导致上述问题,当天线内外圈阵元之间时延差超过10ns时,会引发显著的伪码测距测量值偏离载波相位测量值的现象,当天线内外圈阵元之间时延差达到30ns时,仿真结果与国外文献观测结果高度一致。最后,给出避免此类问题的设计准则:在导航卫星有效载荷天线设计过程中,除了考虑天线阵元载波相位是否符合设计值,还要考虑各阵元间伪码相位的一致性;在后期测试过程中,天线内外圈阵元间时延一致性是必须检测的关键指标。

The code pseudorange and ranging carrier phase ranging are two basic observations of the PNT（Positioning,navigation and time）service.There were code-carrier divergences of the BeiDou Regional Satellite Navigation System described by other articles,and the divergences were elevation-dependent.This article studied the influence mechanism of pseudorange variations of navigation satellite by the discriminator code-tracking error method,and established the mathematic model of the multipath effect assessment.The simulation results showed that when the delay consistence between the inner ring and the outer ring of the satellite payload antenna array elements was over 10 nanoseconds,there would be obvious divergences.When the delay consistence was over 30 nanoseconds,the simulation results were in good agreement with the observation results.The design guidelines to avoid such anomalies are given in this article：for the development of the satellite payload antenna design,one of the most important steps is the phase design within the main-lobe beam width,not only carrier phase but also pseudo-random code phase should be considered.And the delay consistence between the inner rings and the outer rings of the satellite antenna array elements should be tested and confirmed.