Double phase estimator: new unambiguous binary offset carrier tracking algorithm

Several new global navigation satellite system modulations adopt a binary offset carrier (BOC) subcarrier to shape the signal spectrum, increase the frequency separation and improve the tracking performance. BOC modulated signals are, however, characterised 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 study, 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 is replaced by a subcarrier phase lock loop. In the presence of signal bandlimiting, the DPE is able to generate local signal replicas matched in a better manner to the input components, outperforming the DE. The performance of the DPE is thoroughly characterised and the processing of real wideband 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 wideband BOC signals.