CWI effects on code tracking performance of noncoherent delay lock loop

摘要

A continuous frequency spectrum of spread spectrum signal is introduced to investigate the effects of continuous wave interference (CWI) on the code tracking performance, and a noncoherent delay lock loop is employed. This paper provides analytical expressions of code tracking error under CWI, with the consideration of front-end bandwidth, PRN code, early-late spacing and integration time. The demodulation loss induced by the interference and squaring loss of noncoherent discriminator are presented. The maximum bias for different initial phases is also derived. Theoretical results show that the effect of CWI is closely related to the interference characteristics, the specific PRN code and the architectural choices. The interference not only changes the discriminator slope but also induces a code tracking bias. The impact of the interference is more significant when the interference is located around odd integral multiple of the half of the chipping rate. Meanwhile, simulation is carried out to examine behavior of the analytical expressions, proving that the theoretical analysis can accurately predict the code tracking error in the presence of CWI.