Iterated Posterior Linearisation Filtering for Digital Carrier Synchronisation

This paper introduces a new digital carrier synchronization method that employs the Iterated Posterior Linearization Filter (IPLF) to address the challenges posed by nonlinear observation models and ionospheric scintillation in Global Navigation Satellite Systems (GNSS). Although the traditional Phase-Locked Loop (PLL) is widely used due to its simplicity and effectiveness, it exhibits limitations in high-dynamic environments such as ionospheric disturbances. This study enhances synchronization accuracy by employing Statistical Linear Regression (SLR) based on posterior probability density functions of measurement models and incorporating ionospheric scintillation phase into the state variable. Simulation results indicate that the carrier synchronization approach using IPLF achieves higher precision compared to standard PLL and non-iterative nonlinear Kalman filters.