Multi-Frequency Kalman Filter Carrier Phase Tracking for Ionospheric Scintillation Mitigation and Monitoring

This paper presents a detailed analysis of multi-frequency carrier phase tracking algorithms based on Kalman filter (KF) and Extended Kalman filter (EKF) frameworks enhanced by vector autoregressive (VAR) models, under mild, moderate, and severe synthetic equatorial ionospheric scintillation events generated using a multi-frequency phase screen model that includes refractive and diffractive phase fluctuations. A generic discrete multi-frequency state-space model (SSM) of the line-of-sight (LOS) dynamics is derived as a Wiener process and the feasibility of using VAR models to represent the ionospheric scintillation effects is analyzed. Our findings reveal that multi-frequency VAR models significantly outperform single-frequency autoregressive (AR) models in decoupling LOS dynamics from ionospheric scintillation effects, with multi-frequency algorithms demonstrating superior performance in most conditions. The algorithms proposed in this study may be used to enhance ionospheric scintillation mitigation and monitoring in modern software-defined radio receivers.