卫星导航接收机延迟锁定环鉴相器有限字长分析

摘要

Code phase discriminator is the important part of the delay-locked loop,so its performance affects the pseudo-code tracking precision of receiver directly.Aim at influence of the input signal’s finite word-length effect on the discriminator’s performance,a new method based on signal statistical character was proposed and the effect of input signal ’s finite-word length of unified early minus late amplitude discriminator on output performance was analyzed.Analysis and simulation show that the influence of input signal’s finite word-length effect in the case of high SNR(Signal-to-Noise Ratio)is more obvious than in the case of low SNR.The loss of pseudo-code tracking precision caused by finite word length increases as the increasing of input signal’s SNR.The deviation of the code phase discriminator with up to 4 bits almost has not influence on the pseudo-code tracking accuracy.This conclusion can be used to guide the low power and miniaturization design of receiver.%码相位鉴别器作为延迟锁定环的主要组成部分，其性能直接影响了接收机伪码的跟踪精度。针对输入信号有限字长效应对鉴相器性能的影响，提出一种新的基于信号统计特性的分析方法，分析了归一化早迟幅度鉴相器输入信号有限字长对输出性能的影响。理论分析和仿真结果表明，字长效应在输入信号高信噪比下比低信噪比时明显，随着信噪比的增加，由有限字长导致的伪码跟踪精度损失将增加，而当输入信号采用4bit以上的量化时，字长效应对伪码跟踪性能的影响将可忽略。该结论可用于指导接收机低功耗小型化设计。