A High-Precision Acquisition Algorithm for DSSS Signals in Low CNR Scenarios Using 2-D Parallel Fuzzy Logic Control

This paper proposes a fast, high-precision acquisition algorithm based on two-dimensional parallel fuzzy logic (FL) control for direct sequence spread spectrum signals in Lunar-Earth telemetry, tracking, and command (TT&C) scenarios with high dynamics and low carrier-to-noise ratio (CNR). The algorithm initially conducts a rapid coarse search over Doppler frequency and code phase, and subsequently employs FL controllers to adaptively refine both estimates, achieving sub-grid precision. Compared to conventional methods that apply fine search only along the Doppler frequency dimension, the proposed approach integrates FL control with double block zero padding (DBZP). It implements a two-dimensional parallel fine search, enabling simultaneous fine-tuning of both Doppler frequency and code phase. This approach enhances detection performance while improving search efficiency. Simulation results demonstrate that the proposed algorithm effectively reduces acquisition errors and improves acquisition probability in low CNR scenarios.