A Modified PN Code Tracking Loop: Its Performance Analysis and Comparative Evaluation

A modified noncoherent PN code tracking loop (MCTL) has been previously presented by the authors (see Proc. Nat. Telecommun. Conf., Houston, p.61-5, 1981). The loop was shown to have the hardware simplicity of the tau-dither loop and a tracking performance superior to the traditional delay-locked code tracking loop (TCTL). Further work conducted herein expands on these previous results by considering the band-limiting effects of the bandpass arm filters on the performance of the MCTL. It is shown that an even greater improvement in tracking performance is experienced by the MCTL over the TCTL when such effects are included. Furthermore, it was mentioned previously that a specific S/N existed below which the MCTL acquisition behavior was superior to the TCTL and above which its behavior was inferior. The band-limiting effects are shown to have a more deleterious effect on the TCTL and, as such, the crossover S/N will increase, thus enhancing the comparable capabilities in favor of the MCTL. This paper also discusses the implementation sensitivities to hardware gain and phase imbalance by expanding on the noise-free work to include the noisy case.