An Enhanced SDPE Method for Long Delay Multipath Mitigation in GNSS Applications

Abstract

In Global Navigation Satellite System (GNSS) applications, the Binary Offset Carrier (BOC) modulation provides superior benefits vis-a-vis the classical Binary Phase Shift Keying (BPSK) one. Nevertheless, this modulation type presents a major drawback due to the presence of secondary peaks in envelope of the received signal Autocorrelation Function (ACF). This is due to the fact that the ACF side peaks may create false lock points in the Discrimination Function (DF) envelope of the Delay Locked Loop (DLL) structure, producing ambiguity in both acquisition and tracking processes. In the present paper, the Strobe Double Phase Estimator (SDPE) technique for multipath (MP) effect reduction is used in BOC modulated signals acquisition and its performance is analyzed and then enhanced by applying a proposed scheme that is efficient and valid for all BOC modulated signals. The suggested method is based on the use of the SDPE approach for coherent configuration in conjunction with the same approach for non-coherent configuration. As result, the ACF resulting from this combination is unambiguous. Besides, a large evaluative comparison between the new algorithm and the SDPE technique is achieved together with a performance evaluation of the proposed method in MP environment based on the Root Mean Square Error (RMSE) criterion. The obtained results have shown that our proposed scheme presents better performances in the presence of MP.