Evaluation of Low Latitude Scintillation Data with a Dual Kalman Smoother

In this paper an analysis of scintillation phase and amplitude from measurement data with a new dual smoother scheme is performed. The measurement data was obtained in Fortaleza, Brazil, during an ionospheric scintillation event in April 2016. Ionospheric scintillations affect the global navigation satellite system’s (GNSS) signal in amplitude and phase. Both, the scintillation phase and amplitude, are temporally correlated stochastic processes which can severely disturb the signal tracking if not considered in the tracking process. To overcome this problem, the statistics of scintillation phase and amplitude can be modeled as an auto-regressive process. In this paper both, the line-of-sight (LOS) and scintillation parameters, are tracked with a Kalman filter. For the estimation of the non-deterministic auto-regressive parameters, a dual Kalman filter approach which allows to estimate the auto-regressive parameters in parallel to the LOS and scintillation signal parameters is applied. In this paper an additional post-processing scheme based on a Rauch-Tung-Striebel smoother is proposed, which allows for a more reliable estimation of the LOS and scintillation parameters compared to simple tracking for both simulated and measured scintillation data series. The proposed approach is particularly applicable to monitoring applications, where only near real-time operation is desirable.