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Author: search.filters.author.Supnithi, PornchaiSubject: search.filters.subject.Ionospheric delay gradient

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    The Improvement of Time-step method for Ionospheric Delay gradient Estimation
    (2019-06-01)
    Budtho, Jirapoom
    ;
    Supnithi, Pornchai
    ;
    Saito, Susumu
    Ground-Based Augmentation System (GBAS) is concerned with the aircraft positioning correction for precision landing. The ionospheric irregularity is a major impediment of the performance of GBAS. When an airport has at least 2 Global Navigation Satellite System (GNSS) stations, the ionospheric delay gradients can be obtained by using the dual-frequency GNSS stations. If there is only 1 GNSS station in the area, the time step-method can be used. Normally, the baseline from the time-step method is varied according to the sampling rate of GNSS data. Although the sampling rate of the GNSS receiver is a constant value, the baseline varies due to the speed of the GNSS satellite, observed from the ground reference, which can be up to 20 difference km. This paper proposes the dynamic Time-Step method which designates the baseline by adjusting the time between 2 snapshots. The results show that the range of baseline from the reference time-step method, which is set to 1 minute of the sampling rate, can be reduced to 0.5-km variation.
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    Study of ionospheric delay gradient based on GPS monitoring stations near Suvarnabhumi airport in Thailand
    (2014-01-01)
    Rungraengwajiake, Sarawoot
    ;
    Supnithi, Pornchai
    ;
    Saito, Susumu
    ;
    Siansawasdi, Nattapong
    ;
    Saekow, Apitep
    The ionospheric delay gradient is an important parameter for the planning of ground-based augmentation system (GBAS) in a region. When it is beyond the limit, the integrity and safety for landing approach of CAT II/III may be compromised. In order to maintain the availability and safety requirement of the system, the ionospheric threat models have been developed in several countries during the past few years. However, the ionospheric delay gradient associated with plasma bubble in low latitude region has not been studied well. In this work, we present some analytical results of ionospheric delay gradient based on three GPS monitoring stations near Suvarnabhumi airport in Thailand. The stations are located on the campus of King Mongkut's Institute of Technology Ladkrabang (13.7278°N, 100.7726°E), Stamford University (13.7356°N, 100.6612°E) and Suvarnabhumi airport (13.6945°N, 100.7608°E). The analyzed results on 1st September 2011 show that the ionospheric delay gradient varies from -95.23 to 107.7 mm/km during the occurrence of the plasma bubbles. © 2014 Springer.
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    Preliminary results of ionospheric delay gradients study near Suvarnabhumi airport in Thailand
    (2013-12-09)
    Runraengwajiake, Sarawoot
    ;
    Supnithi, Pornchai
    ;
    Kenpankho, Prasert
    ;
    Saekow, Apitep
    ;
    Saito, Susumu
    Ground-Based Augmentation System (GBAS) is an augmentation system support for GNSS to provide a differential correction and integrity information to the aircraft for landing approach. However, the ionospheric disturbances can cause the ionospheric delay gradient between the reference stations and the aircraft and may degrade the accuracy and safety level of GBAS. In this work, we present some preliminary results of the ionospheric delay gradients in terms of the difference of slant TEC (total electron content) using GPS monitoring stations near Suvarnabhumi International airport, Bangkok, Thailand. Based on the data on 1<sup>st</sup> September, 2011, the results show that the slant TEC between two nearby stations are different during plasma bubble occurrence. In addition, we also compute the speed of moving plasma bubble by estimating the delay time between slant TEC patterns. © 2013 IEEE.