短延迟多径干扰下的跟踪环路鉴别器设计

Design of the discriminator for tracking the loop under short-delay multipath interference

针对短延迟多径干扰影响下传统多径消除方法性能下降的问题,提出了一种跟踪环路鉴别器的构造方法.首先分析了短延迟多径下同相/正交超前、滞后与即时支路的输出特性,在此基础上构建出一种改进的超前支路;将环路鉴别器的输出定义为归一化超前减滞后功率型函数,从而使得直达信号码相位与本地估计码相位的误差小于预设门限值.理论分析和仿真结果表明,与传统多径抑制方法相比,基于改进环路鉴别器的多径抑制技术,能够减小相对时延小于0.5码片时多径带来的码跟踪误差,有效抑制了短延迟多径干扰,进而提高了导航与对接系统中的跟踪测量精度.

The traditional multipath eliminating methods have poor performance under short-delay multipath interference and therefore a discriminator constructing method for tracking the loop is presented.Firstly,from the analysis of the output characteristics for in-phase/quadrature-phase early,late,and prompt channels under the short-delay multipath,an improved late channel is constructed.The output of the loop discriminator is defined as the normalized function of the power difference between early and late signals.It made the error between the code phase of the direct signal and that of the local estimated signal is less than the pre-determined threshold.Theoretical analysis and simulation results show that,compared to traditional methods,the multipath mitigation technique based on the improved loop discriminator can suppress the code tracking errors produced by the multipath when the relative delay is less than 0.5chip and effectively inhibits short-delay multipath interference,thus improving the tracking and measurement accuracy in navigation and docking systems.