Publication: Investigation of ionospheric effects on ground based augmentation systems at low latitude region
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Date
2024-09-01
Authors
Brelveenraj Kaur, A/P Rajwant Singh
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Abstract
Space-based technologies such as the Global Navigation Satellite Systems
(GNSS) are playing an increasingly important role in aviation navigation due to the
increasing demand for long-haul air travel. This encouraged airports to deploy Ground
Based Augmentation System (GBAS) replacing the Instrument Landing System (ILS)
which resulted in reduced delays and disruptions for travellers. Low latitudes and
equatorial regions, such as Malaysia are more likely to experience ionospheric
disturbances caused by solar activity and geomagnetic storms, which disturb the GNSS
signals. The performance of the GNSS is subjected to risk as the integrity of the GBAS
between the ground receiver and the aircraft deteriorates. This study analyse
ionospheric scintillation and Total Electron Content (TEC) effects on the GBAS
receivers installed at KLIA. The data collected was during solar minimum which
reflected towards the GBAS in KLIA not experiencing any anomaly events that could
disrupt the GPS receiver's signal during equinox months. The amplitude scintillation,
S4 index values were found within (0.2 < S4< 0.5), indicating weak or negligible
scintillation. The GBAS receivers consistently show of spikes of S4 data at precise
times across the months, suspected due to nearby interference rather than active
scintillation events. The TEC values vary from a low in the early hours of the day to a
diurnal maximum between 15:00 LT and 18:00 LT before falling to a minimum in the
afternoon. The TEC were particularly higher in September and March corresponding
to the months of equinox. This paper investigates the ionospheric disturbance in the
low latitude region and ideas for improving GBAS receiver performance for future
developments.