Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761026
Title: GNSS in aviation : ionospheric threats at low latitudes
Author: Mohd Ali, Aiffah
ISNI:       0000 0004 7432 6919
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2018
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Abstract:
Radio signals propagating through the ionised upper atmosphere (the ionosphere) in low latitude regions of the world can experience amplitude scintillation. This could threaten safety-critical applications of satellite navigation such as aviation. The research presented here studied the effects of amplitude scintillation on a Septentrio PolaRxS geodetic receiver and a Garmin 480 aviation receiver by means of a Spirent GNSS constellation simulator. Different types of fade profiles showed that an abrupt drop in signal strength caused a loss of lock on the signal more often than a profile with a slow, gradual fade. A performance comparison of the two receivers demonstrated that the aviation receiver was more vulnerable than the geodetic receiver. An unexpected loss of lock at a specific fade duration and depth was seen with the Garmin receiver and was not explained. A single fade with a long fade duration was more likely to cause a loss of signal lock compared to rapid multiple fades. Scintillation on signals from low elevation satellites can significantly degrade the precision and integrity of the navigation solution in an aviation receiver; especially if the satellites are within the best geometrical set. RAIM was observed to be no longer available during the critical landing approach phase of the scenario, in the case when all satellites in view were affected by the scintillation-induced signal perturbations. A technique was also developed to simulate L5 scintillation based on real scintillation events of L1, in the absence of real captured data for L5. This was done to enable future investigations on aviation receiver performance when both L1 and L5 frequencies experience scintillation. Analysis indicated that L5 signal can be more vulnerable to the scintillation compared to the L1 signal, which may have important implications for aviation safety.
Supervisor: Mitchell, Cathryn ; Forte, Biagio Sponsor: Universiti Sains Malaysia ; Ministry of Education Malaysia
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.761026  DOI: Not available
Keywords: scintillation ; Aviation ; Equatorial ionosphere ; GNSS
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