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Projecte llegit

Títol: Empirical analysis of the link between ionospheric electron content fluctuations and amplitude fading in GNSS signals

Estudiants que han llegit aquest projecte:

Director/a: GONZÁLEZ CASADO, GUILLERMO

Departament: MAT

Títol: Empirical analysis of the link between ionospheric electron content fluctuations and amplitude fading in GNSS signals

Data inici oferta: 14-01-2025     Data finalització oferta: 14-09-2025


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Gnss, scintillation, ionosphere, monitoring, radionavigation signals
 
Descripció del contingut i pla d'activitats:
The electron content fluctuations of the ionosphere can be regularly monitored by means of Global Navigation Satellite System signals. Moreover, the signal intensity is also normally provided as part of the GNSS carrier phase measurements. The objective of this activity is to analyze the existing correlation between both. To this end, specific monitoring indexes will be used to measure signal amplitude fading and electron content flutuations. The study will be focused on the GNSS receivers located at low latitude regions, affected by fast fluctuations of the ionospheric electron content producing diffraction of GNSS signals. This has a strong impact on signal tracking and ultimately degrades the performance of GNSS for precise positioning applications.

Working plan:

1) Revision of the state of the art of the subject of low-latitude scintillation monitoring.

2) Introduction to scintillation monitoring indexes and GNSS data sets to be used in the study.

3) Getting familiar with visualization of the data sets and definition of the scope of the study.

4) Analysis of the correlation between uncombined ROTI and S4 indexes as a function of:
- GNSS constellation, specifically targeted to GPS and Galileo satellites.
- Type of receiver.
- Ionospheric activity and period of the year.

5) Identification of outliers and anomalies in the correlation analysis. Preliminary study of their origin.

The outcome of this study will serve as the basis to undertake future analysis of the impact of ionospheric scintillation on GNSS signals based on data from long time periods (several years) and wide spatial coverage, reaching a global scale.
 
Overview (resum en anglès):
Ionospheric scintillation affects the electromagnetic signals used in Global Navigation Satellite System (GNSS). This phenomenon consists of rapid fluctuations in the electron content of the ionosphere that produce diffraction and/or refraction on the GNSS signals and, consequently, the signal experiments fading in the signal amplitude and phase cycle slips, potentially leading to loss of lock in receiver tracking.

In low latitude regions, the amplitude scintillation index, S4, is commonly used to quantify diffractive scintillation, as signals in these areas are particularly susceptible to experience diffraction, which affects the amplitude (intensity) of the signal.

The detection and mitigation of the ionospheric scintillation effects remains a significant challenge in navigation, especially in low latitude regions where this phenomenon is relatively understudied compared to high latitude regions.

The aim of this final degree thesis is to analyze scintillation parameters (i.e. Rate of TEC (Total Electron Content) Index (ROTI) and S4) using a dataset provided by the gAGE research group. This dataset contains real-time information collected in the year 2024 with a network of seven receivers from two different GNSS constellations: Global Positioning System (GPS) and Galileo.

Python and MATLAB will be used for data management and computation, respectively. The outcomes are intended to provide a relevant framework for future studies on ionospheric scintillation effects on GNSS signals, and to support the detection of related anomalies.

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