A dual-threshold up-down counter for GPS acquisition

In this work, the up-down counter detector for the acquisition of GPS signals is modified to use dual-thresholds for each trial. Closed form expressions for the mean and variance of the dwell time and the probabilities of detection and false alarm are derived. The new detector has a significantly smaller mean dwell time than the conventional single-threshold up-down counter and a lower dwell time variance when signals are weak. Further, the new detector has a low computational load, when compared to the optimal sequential probability ratio test (SPRT), whose main disadvantage is its computational complexity.