相位非线性畸变对GPS伪距测量的影响

The Impact of Phase Nonlinear Distortion to GPS Pseudo-range Measurement

基于直接序列扩频体制的伪距测量在卫星导航、雷达、航天测控、深空探测等领域获得了广泛应用。射频链路、电缆多径等引入的相位非线性畸变会对扩频信号的传输时延产生影响,进而影响延迟锁定环(DLL)的伪距测量结果。传统群时延的定义难以描述一定带宽内的相位畸变,也难以与扩频信号时延建立对应关系。在对相频曲线进行Taylor展开的基础上给出了群时延的新定义,利用零阶群时延、线性群时延和抛物线群时延等来描述相位畸变,并定量研究各阶群时延对DLL伪距测量的影响。所得结论表明抛物线(二阶)群时延对伪距测量的影响最大。

PN code ranging technique based on DSSS is widely used in satellite navigation, radar, and aerospace TT＆C. The phase distortion introduced by RF link and cable multi-path will greatly affect the signal lime delay of spread spectrum. The traditional definition of group delay is incapable of describing the holistic phase character of signal bandwidth, thus having difficulty in establishing relationship with the spread spectrum signal delay. To resolve these problems, a new group delay definition has been put forward, based on Taylor series expansion, which uses zero order group delay, linear group delay and parabolic group delay to describe phase distortion. The influence of the different order group delay on PN code ranging was analyzed and simulated. The results show that the parabolic group delay has greatest effect on PN code ranging.