Optimal and Near-optimal Detectors for Acquisition of the GPS L5 Signal

Acquisition of GPS signals is typically accomplished by conducting a two-dimensional search of codephase and Doppler using multiple correlators. For each codephase/Doppler value, a detector is used to decide whether the signal is present or not present. This paper derives an optimal detector for the GPS L5 signal in the presence of additive white Gaussian noise. Simplified detectors are also derived as limits of the optimal detector in low- and high- signal-to-noise (SNR) conditions. Monte-Carlo simulation results are presented that demonstrate the performance of the optimal and nearoptimal detectors. For short dwell times, the high-SNR approximation to the optimal detector is the most promising. It significantly outperforms previous noncoherent detectors with only a moderate increase in receiver complexity.