Simultaneous Perturbation Stochastic Approximation for Unambiguous Acquisition in Cosine-BOC Signals

The binary offset carrier (BOC) proposed for the global navigation satellite systems (GNSS) will enhance navigation performance and spectrum compatibility. However, the acquisition process is made more complex, due to the ambiguity in the autocorrelation function (ACF) of BOC. This paper proposes an unambiguous acquisition technique for the new cosine phased BOC (cosine-BOC) modulated signals, which will most likely be used in both European Galileo system and Chinese Compass system. The test criterion employed in this technique is based on a synthesized correlation function which completely removes major positive side peaks while keeping the sharp main peak using the concept of simultaneous perturbation stochastic approximation (SPSA). Theoretical analysis and simulation results indicate that the proposed technique completely removes the ambiguity threat in acquisition process with some performance degradation. This technique is also suitable for arbitrary order cosine-BOC signals.