With the growing reliance on Global Navigation Satellite System (GNSS) for navigation and positioning in autonomous systems, the vulnerability to spoofing attacks has emerged as a critical concern. The increasing deployment of dual-frequency GNSS receivers in vehicular applications has drawn attention to their potential for efficient spoofing detection. Dual-Frequency Doppler Consistency Checking (DFDCC) offers an intuitive approach by assessing the Doppler consistency between two frequency signals. This method not only enables the identification of spoofed signals but also exhibits robustness and flexibility in vehicular scenarios. Despite its practical advantages, DFDCC currently lacks a comprehensive theoretical framework and detailed performance analysis, particularly in the context of vehicular applications. To bridge these gaps, this study aims to develop a theoretical foundation and evaluate the real-world applicability and effectiveness of DFDCC in vehicular scenarios. The paper begins by deriving a Doppler observation model for both authentic and spoofing signals, deriving key sources of Doppler bias. These include the deviation between false and real user states, the spoofer clock bias, and the relative velocity between the spoofer and the user. Besides, extensive simulation experiments are conducted to analyze the influence of these factors on DFDCC performance, revealing an offset phenomenon when multiple factors coexist. This method is further validated through field tests under three typical vehicular motion patterns, demonstrating its feasibility across diverse vehicular scenarios. The results confirm that DFDCC is a viable solution for spoofing detection for autonomous vehicles, offering valuable insights for its practical implementation and serving as a reference for future research.

In global positioning system modernisation, to further enhance the anti‐jamming capability of authorised signals, the new designed M‐code signal utilises a few revolutionary techniques. While enduing the signal with excellent performance, the techniques make the acquisition methods for conventional pseudo‐noise codes, such as C/A‐code and P(Y)‐code, inapplicable. Furthermore, compared with time‐domain correlation, frequency‐domain correlation is favourable for saving computation requirements and suppressing interferences. Thus, it is quite desirable to develop frequency‐domain‐based ones. To this end, a frequency‐domain‐based acquisition method is developed, and based on the method the acquisition performance of M‐code signal is evaluated and the factors associated with the performance are investigated. It is shown that M‐code provides flexible tradeoffs between performance and implementation complexity through the sidebands and chips of the signal. Numerical and simulation results demonstrate the results.

Because of the long period and high chip rate of GPS P-code, direct acquisition is challenging. In the letter, the widely used zero-padding scheme (ZPS) for direct GPS P-code acquisition is generalized to investigate the effects of the ZPS on detection performance, parallel searching capability, and mean acquisition time. It is shown that, by adjusting the zeros padded to received signal according to signal to noise ratio, the generalized zero-padding scheme (GZPS) makes a better tradeoff between detection performance and parallel searching capability and further reduces mean acquisition time. The generalized zero-padding scheme can be easily applied to the previously proposed zero-padding method (ZPM) and the direct average method (DAM) to improve their mean acquisition time performance and it does not increase the implementation complexity of a receiver.

For long PN-code, rapid acquisition is difficult due to large search space. To speed up the search process, extended replica folding acquisition search technique (XFAST), which directly reduces the code phases to be searched by folding local signal, provides an efficient approach to rapid acquisition. Nevertheless, after folding the correlation properties of PNcode are degraded; hence, the detection performance of XFAST to weak signal is worse than that of nonfolding methods. To improve the detection performance, a dual-folding acquisition method (DF) is proposed. By folding both incoming signal and local signal, DF extends coherent integration time to enhance detection performance and indirectly reduce mean acquisition time. Numerical results demonstrate the enhancement of the proposed method with respect to other methods such as serial search (SS), zero-padding method (ZP), and XFAST.