卫星导航接收机延迟锁定环鉴相器有限字长分析

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。
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.