Codeless and semi-codeless techniques are recently finding new and unexpected applications. For example, they can be used as an effective means for signal authentication and spoofing detection. In this paper, codeless tracking is adopted for processing Binary Offset Carrier (BOC) modulated signals where a Subcarrier Lock Loop (SLL) is used to remove the subcarrier component. The developed system is then used for signal quality monitoring of encrypted Global Navigation Satellite System (GNSS) signals. In this respect, a multi-correlator codeless architecture and a codeless Carrier-to-Noise density power ratio (C/N0) estimator are developed and tested under different operating conditions. The effectiveness of the proposed codeless framework is tested using real data collected from the Galileo IOV satellites. The analysis supports the validity of the proposed architecture which enables quality monitoring of encrypted GNSS signals.
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