Incipient anomalous ionospheric divergence fast detection for coastal differential Global Navigation Satellite System

Abstract

Differential Global Navigation Satellite System (DGNSS) plays an increasingly important role in the maritime field. Irregular ionospheric divergences may result in DGNSS performance degradation and increase risk in terms of positioning accuracy and navigation integrity. To speed up incipient ionospheric anomaly detection, this paper proposes a novel method for the DGNSS stations which employs (1) the Wasserstein distance (WD) to identify dissimilarity between GNSS pseudorange and carrier-phase measurements and (2) the least-mean-square (LMS) filter to smooth the calculated metrics. The combined WD-LMS is proposed to ensure the rapid identification of abnormal ionospheric divergences. Taking the multipath into account, which is especially severe in the low elevation angle case, elevation-angle related strategies are developed. Both semi-simulated and real experiments are conducted. For the high-elevation angle case, the WD-LMS is even potential to detect large ionospheric divergences within ten epochs. Therefore, the WD-LMS has encouraging potential to enhance maritime DGNSS navigation performance.