Double Phase Estimator: a New Unambiguous BOC Tracking Algorithm

Several new Global Navigation Satellite System (GNSS) modulations adopt a Binary Offset Carrier (BOC) subcarrier to shape the signal spectrum, increase frequency separation and improve tracking performance. BOC modulated signals are however characterized by ambiguous multi-peaked correlation functions and several techniques have been proposed in the literature to solve the problem of locking into secondary peaks. In this paper, a novel unambiguous BOC tracking technique, the Double Phase Estimator (DPE), is designed to account for the effect of signal bandlimiting. The DPE is an effective alternative to the Double Estimator (DE) tracking technique where the Subcarrier Lock Loop (SLL) is replaced by a Subcarrier Phase Lock Loop (SPLL). In the presence of signal bandlimiting, the DPE is able to generate local signal replicas better matched to the input components outperforming the DE. The performance of the DPE is thoroughly characterized and processing of real wide-band BOC signals is used to demonstrate the effectiveness of the algorithm proposed. In addition to this, the DPE requires a lower computational load than the DE and thus should be adopted for the processing of wide-band BOC signals.