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1

A combined iCEEMDAN and VMD method for mitigating the impact of ionospheric scintillation on GNSS signals

Dey Abhijit, Chhibba Rohan, Ratnam Devananboyina Venkata, Sharma Nitin

Acta Geophysica

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2021

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Vol. 69, no. 5

1933--1948

EN

Severe amplitude and phase scintillation induced by the ionospheric plasma density irregularities degrades the performance of global navigation satellite system (GNSS) receivers. Scintillation typically has adverse effects at the tracking process and thus adversely affects the raw GNSS measurements used in a number of applications. Hence, it is important to develop robust methodologies for detecting and mitigating ionospheric effects on the GNSS signals. In this paper, we propose a novel method based on the combination of improved complete ensemble empirical mode decomposition with adaptive noise (iCEEMDAN) and variational mode decomposition (VMD) methods. The proposed method employs a detrended fuctuation analysis (DFA)-based metric for robust thresholding between the scintillation-free and amplitude scintillated GNSS signals. The major contribution of the proposed method is development of novel approaches for selection of intrinsic mode functions (IMFs) based on DFA and optimised selection of [K, 훼] parameters of the VMD. The performance of the proposed method was evaluated and was observed that it is better than existing ionospheric scintillation effects mitigation algorithms for both simulated and real-time GPS scintillation datasets. The proposed method can denoise approximately 9.23–15.30 dB scintillation noise from the synthetic and 0.2–0.48 from the real scintillation index (S4) values. Therefore, the proposed (iCEEMDAN-VMD) method is appropriate for mitigating the ionospheric scintillation effects on the GNSS signals.

2

Detection of ionospheric scintillation effects using LMD–DFA

Tadivaka R. V., Paruchuri B. P., Miriyala S., Koppireddi P. R., Devanaboyina V. R.

Acta Geophysica

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2017

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Vol. 65, no. 4

777--784

EN

The performance and measurement accuracy of global navigation satellite system (GNSS) receivers is greatly affected by ionospheric scintillations. Rapid amplitude and phase variations in the received GPS signal, known as ionospheric scintillation, affects the tracking of signals by GNSS receivers. Hence, there is a need to investigate the monitoring of various activities of the ionosphere and to develop a novel approach for mitigation of ionospheric scintillation effects. A method based on Local Mean Decomposition (LMD)–Detrended Fluctuation Analysis (DFA) has been proposed. The GNSS data recorded at Koneru Lakshmaiah (K L) University, Guntur, India were considered for analysis. The carrier to noise ratio (C/N0) of GNSS satellite vehicles were decomposed into several product functions (PF) using LMD to extract the intrinsic features in the signal. Scintillation noise was removed by the DFA algorithm by selecting a suitable threshold. It was observed that the performance of the proposed LMD–DFA was better than that of empirical mode decomposition (EMD)–DFA.

3

GPS Amplitude Scintillations over Kampala, Uganda, During 2010-2011

Akala A. O., Idolor R., D'Ujanga F. M., Doherty P. H.

Acta Geophysica

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2016

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Vol. 64, no. 5

1903--1915

EN

This study characterizes equatorial scintillations at L1/L2 GPS frequency over Kampala (0.30°N, 32.50°E, mag. lat. 9.26°S), Uganda, on different time scales during the minimum and ascending phases of solar cycle 24 (2010-2011). Of all the days investigated, 25 October 2011 recorded the highest occurrence of scintillation, and it was attributed to geomagnetic storm occurrence. We used the data of 25 October to generate plots of the elevation angle and S4 index against local time on a satellite-by-satellite basis, with a view to distinguishing satellites links whose signals were impaired by ionospheric irregularities from those impaired by multipath. Conclusively, GPS amplitude scintillations over Kampala occur predominantly during post sunset hours and decay around midnight. Equinoctial months recorded the highest occurrences of scintillations, while June solstice recorded the least. Scintillation occurrences also increase with solar and geomagnetic activity.

4

Monitoring ionospheric scintillations and TEC at the Polish Polar Station on Spitsbergen: instrumentation and preliminary results

Wernik A., Pożoga M., Grzesiak M., Rokicki A., Morawski M.

Acta Geophysica

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2008

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Vol. 56, no. 4

1129-1146

EN

As a partial contribution to the International Polar Year, the Space Research Centre of the Polish Academy of Sciences has installed on the Polish Polar Station, located in the region of the Hornsund Bay in southern Spitsbergen, the equipment intended to monitor ionospheric scintillation and total electron content. We describe the equipment setup and the aims of the experiment. As an illustration of data analysis, we present the reconstruction of irregular structure of the ionosphere from the complex amplitude data, and the estimate of the form and drift of diffraction pattern based on the spaced receiver measurements.

5

Ionospheric irregularities, scintillation and its effect on systems

Wernik A., Alfonsi L., Materassi M.

Acta Geophysica Polonica

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2004

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Vol. 52, nr 2

237-249

EN

An essential component of the ionosphere is a small-scale electron density structure that causes scintillation of radio waves on transionospheric links. We briefly review the morphology of irregularities and physical mechanisms of their formation. Results of the scintillation theory relating statistical characteristics of irregularities and scintillation are also outlined. Examples of the scintillation effect on the system performance are given. Finally, we will present recent attempts to model the scintillation.