Sub-carrier shaping for BOC modulated GNSS signals

One of the main challenges in Binary Offset Carrier (BOC) tracking is the presence of multiple peaks in the signal autocorrelation function. Thus, several tracking algorithms, including Bump-Jump, Double Estimator, Autocorrelation Side-Peak Cancellation Technique and pre-filtering have been developed to fully exploit the advantages brought by BOC signals and mitigate the problem of secondary peak lock. In this paper, the advantages of pre-filtering techniques are explored. Pre-filtering techniques based on the concepts of Zero-Forcing and Minimum Mean Square Error equalization are proposed. The BOC sub-carrier is modeled as a filter that introduces secondary peaks in the autocorrelation function. This filtering effect can be equalized leading to unambiguous tracking and allowing autocorrelation shaping. Monte Carlo simulations and real data analysis are used to characterize the proposed algorithms.