Detection of GPS and BDS flex power for mitigating its impact on satellite-based services

Abstract As a key method to enhance the anti-jamming capability of Global Navigation Satellite System (GNSS), flex power technology enables ground-based commands to dynamically adjust satellite signals by redistributing signal components, thereby strengthening specific transmissions and improving service robustness in interference environments. Both the Global Positioning System (GPS) and the BeiDou Navigation Satellite System (BDS) support flex power functionality. Activating and deactivating of flex power can significantly impact the various aspects of GNSS performance and introduce new technical challenges. In this paper, we first analyze the flex power operational modes of GPS and BDS, then review existing detection methods to propose a novel detection approach applicable to both GPS and BDS. The proposed method employs carrier-to-noise density ratio (C/N 0 ) and hardware delay as complementary indicators to achieve high detection accuracy with low false alarm rates. Subsequently, we investigate the impacts of flex power on cycle slip detection, code bias, satellite clock offset, phase bias, ionospheric corrections, and Precise Point Positioning (PPP). The results show that flex power affects several GNSS parameters with BDS exhibiting much greater sensitivity compared to GPS. To address these effects and advance resilient Positioning, Navigation, and Timing (PNT) theory, we propose the optimized estimation strategies for resilient code bias, satellite clock offset, and phase bias, along with an enhanced data processing framework for ionospheric modeling and PPP. The effectiveness of the proposed approaches is validated, demonstrating clear improvements in PNT service reliability. This study provides valuable insights and practical methodologies for enhancing the robustness of GNSS PNT services in flex power operations.