卫星导航接收机延迟锁定环鉴相器有限字长分析

Analysis of finite word length effect on delay-locked loop discriminator in GNSS 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。

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.