access icon openaccess Cross-correlation codeless processing of BOC modulated signals

This is an open access article published by the IET under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/)
Received 08/01/2019, Accepted 15/04/2019, Revised 20/03/2019, Published 15/07/2019

Encrypted global navigation satellite system signals (GNSS) can be tracked using codeless techniques that do not require the knowledge of the spreading code used for signal generation. These techniques can also be applied to binary offset carrier (BOC) modulated signals whose unknown code sequence can be removed through squaring. In this study, an alternative codeless approach based on the cross-correlation principle is considered. Cross-correlation codeless processing is commonly used for tracking signal components on different frequencies, such as the global positioning system (GPS) L1 and L2 P(Y) signals, and it is adapted here to BOC modulations broadcast on a single frequency. A cross-correlation codeless framework is proposed where the BOC signal is split into two data streams that are cross-multiplied to remove the unknown code sequence. Two architectures, open-loop and closed-loop processing, are proposed and analysed. The codeless cross-correlation function is introduced and open-loop processing is used to reconstruct it from the received samples. Closed-loop processing based on cross-correlation phase lock loop (PLL) and delay lock loop (DLL) are used to estimate the signal parameters. The proposed cross-correlation framework is thoroughly analysed theoretically, through simulations and using real data. The analysis shows the effectiveness of the cross-correlation framework.

Inspec keywords: modulation; correlation methods; phase locked loops; delay lock loops; signal reconstruction

Other keywords: global positioning system; closed-loop processing; delay lock loop; cross-correlation codeless processing; signal parameters; binary offset carrier modulated signals; unknown code sequence; cross-correlation framework; BOC modulated signals; signal generation; open-loop processing; alternative codeless approach; signal component tracking; cross-correlation phase lock loop; encrypted global navigation satellite system signals; codeless cross-correlation function

Subjects: Signal processing and detection; Modulation and coding methods; Signal processing theory

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