Linear time-invariant filtering for real-time monitoring of ionospheric scintillation in GNSS receivers

We propose an algorithm for estimating the ionospheric scintillation phase on global navigation satellite systems (GNSS) receivers for scintillation monitoring. The algorithm comprises linear time-invariant filtering of available observables or easily derived in traditional or Kalman filter-based carrier tracking loop structures, exploiting their complementary frequency content to provide real-time scintillation phase estimates for monitoring purposes. This algorithm is developed for receivers with traditional and Kalman frequency locked loops, but can be adapted to receivers with traditional and Kalman phase locked loops. The performance of the algorithm is evaluated via simulations with synthetic severe scintillation data, showing its capability to provide the scintillation phase estimates. In addition, we evaluated the algorithm with real data presenting equatorial scintillation collected by a professional GNSS receiver, where the scintillation phase standard deviation computed from the estimates provided by the real-time algorithm is compared to the standard deviation derived by post-processing, showing good agreement.