Performance of Standard Code-Tracking Loops in the Presence of Dual Tone Interference

The performance of sum/difference and reference/difference code tracking loops in direct-sequence spread-spectrum communication systems are fully analyzed and compared for nonwhite interference situations. In particular, symmetric dual-tone interference is considered and the worst case tone spacing and relative tone energies are determined. Parameterized curves of tracking-error variance and mean-time to lose lock are presented as a function of signal-to-interference ratio, dual tone spacing, and early-late gate delay difference.