Characterization of low latitude ionospheric scintillations using EEMD - DFA method

摘要

Global Navigation Satellite System (GNSS) receivers are used in various applications like navigation, surveying, mapping, space weather prediction and aircraft landing, which are mostly used to meet various civil and defence requirements. Ionospheric scintillations are one of the dominant propagation impairments at L-band frequencies that affect GNSS signals severely. Amplitude scintillations cause the degradation of GPS signal amplitude and are observed frequently during geomagnetic storms. These scintillations can degrade the GNSS receiver tracking performance and in worst cases, even cause the loss of navigational capabilities. In this paper, ensemble empirical mode decomposition (EEMD) and empirical mode decomposition (EMD) were used as statistical significance models for which detrended fluctuation analysis (DFA) was conducted to determine the threshold for robust denoising performance. Frequency energy distribution was exemplified as a function of time. The key idea of this paper is denoising, in which the intrinsic mode functions (IMF) with noisy oscillations are suppressed and the IMFs with slope values beyond the threshold are considered for reconstruction. Ionospheric data recorded at KL University, Guntur is used for the analysis. It is found that the EEMD - DFA method performs better than existing methods.