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Ghobadi, Hossein
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Ghobadi, Hossein
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hossein.ghobadi@ingv.it
3 results
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- PublicationOpen AccessAdaptive Phase Detrending for GNSS Scintillation Detection: A Case Study Over Antarctica(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We aim at contributing to the reliability of the phase scintillation index on Global Navigation Satellite System (GNSS) signals at high-latitude. To the scope, we leverage on a recently introduced detrending scheme based on the signal decomposition provided by the fast iterative filtering (FIF) technique. This detrending scheme has been demonstrated to enable a fine-tuning of the cutoff frequency for phase detrending used in the phase scintillation index definition. In a single case study based on Galileo data taken by a GNSS ionospheric scintillation monitor receiver (ISMR) in Concordia Station (Antarctica), we investigate how to step ahead of the cutoff frequency optimization. We show how the FIF-based detrending allows deriving adaptive cutoff frequencies, whose value changes minute-by-minute. They are found to range between 0.4 and 1.2 Hz. This allows better accounting for diffractive effects in phase scintillation index calculation and provides a GNSS-based estimation of the relative velocity between satellite and ionospheric irregularities.812 66 - PublicationOpen AccessUser-Oriented ICT Cloud Architecture for High-Accuracy GNSS-Based Services(2019)
; ; ; ; ; ; ; ; ;; ;; ; We introduce a new information and communication technology (ICT) cloud-based architecture for Global Navigation Satellite System (GNSS) high-accuracy solutions, offering also a commercial overview of GNSS downstream market to show how the developed innovation is thought to fit in the real context. The designed architecture is featured by dynamic scalability, increased integrity, and greater agility of the ICT system. The novelty of the solution developed is a customized ICT architecture, obtained through unique and privileged access to user communities in the frame of the H2020 project TREASURE, allowing the development of a solution entirely driven by user needs. The economic outlook of GNSS downstream markets evolution highlights how the technology proposed effectively matches the evolving business environment, specifically in regard to the increasing need for flexibility and competitive advantage deriving from services. The simultaneous adoption of the technical and commercial perspective is meant to offer interesting findings to both the scientific community and GNSS industry, creating synergies previously unexplored.920 22 - PublicationOpen AccessDisentangling ionospheric refraction and diffraction effects in GNSS raw phase through fast iterative filtering technique(2020-06-29)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We contribute to the debate on the identification of phase scintillation induced by the ionosphere on the Global Navigation Satellite System (GNSS) by introducing a phase detrending method able to provide realistic values of the phase scintillation index at high latitude. It is based on the Fast Iterative Filtering (FIF) signal decomposition technique, which is a recently developed fast implementation of the well-established Adaptive Local Iterative Filtering (ALIF) algorithm. FIF has been conceived to decompose nonstationary signals efficiently and providing a discrete set of oscillating functions, each of them having its frequency. It overcomes most of the problems that arise when using traditional time-frequency analysis techniques and relies on a consolidated mathematical basis since its a priori convergence and stability have been proved. By relying on the capability of FIF to efficiently identify the frequencies embedded in the GNSS raw phase, we define a method based on the FIF-derived spectral features to identify the proper cutoff frequency for phase detrending. To test such a method, we analyze the data acquired from GPS and Galileo signals over Antarctica during the September 2017 storm by the Ionospheric Scintillation Monitor Receiver (ISMR) located in Concordia Station (75.10°S, 123.33°E). Different cases of diffraction and refraction effects are provided, showing the capability of the method in deriving a more accurate determination of the SigmaPhi index. We found values of cutoff frequency in the range of 0.73 to 0.83 Hz, providing further evidence of the inadequacy of the choice of 0.1 Hz, which is often used when dealing with ionospheric scintillation monitoring at high latitudes.1163 54