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Author: search.filters.author.Supnithi, PornchaiSubject: search.filters.subject.SPP

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    Investigations of User Positioning Errors by Using Local DFMC SBAS Correction with Higher-Order Ionospheric Delay Mitigation in Thailand
    (2024-01-01)
    Sophan, Somkit
    ;
    Supnithi, Pornchai
    ;
    Myint, Lin M.M.
    Dual-frequency multi-constellation (DFMC) satellite-based augmentation system (SBAS) is essential to support airplane navigation. Typically, the global navigation satellite system (GNSS) with the L1 (1575.42 MHz) and L5 (1176.45 MHz) frequencies are utilized to remove the ionospheric delays based on the ionosphere-free (IF) combination (L1-L5), nevertheless, the errors due to higher-order ionospheric (HOI) delays still need to be corrected. With the local DFMC SBAS correction with a HOI mitigation in Thailand had not been considered and investigated yet. Therefore, we investigate local DFMC SBAS corrections with the HOI mitigation which are generated from the base stations in Thailand. The corrections are approximated from the local total electron content (TEC) values based on the Klobuchar model. Firstly, the local HOI days are estimated by using the observed pseudorange, and consequently, the local DFMC SBAS corrections are generated based on the minimum sum-variance technique with the IF carrier smoothing code. The GPS, Galileo, and QZSS data from the reference stations network in Thailand are utilized. In the preliminary study, the user positioning errors on the quiet days are evaluated based on the single point positioning (SPP) algorithm. The results show that both horizontal and vertical position errors are reduced by the local DFMC SBAS corrections with the HOI mitigation. The position error improvements on the quiet days can be experienced by 11%.
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    Improvement of single point positioning accuracy by using GAGAN satellite-based augmentation system in Thailand Region
    (2021-05-19)
    Sophan, Somkit
    ;
    Phakphisut, Watid
    ;
    Myint, Lin M.M.
    ;
    Supnithi, Pornchai
    Although GAGAN satellite-based augmentation system (SBAS) provides ionospheric correction service to India and surrounding areas, the correction values do not cover the entire region of Thailand and even at provided grids, they may not be sufficiently accurate. Hence, this work, we propose a local ionospheric delay estimation method based on the geo-free ionospheric delay estimation. Then the estimated ionospheric delays are applied together with the fast and long-term corrections of GAGAN SBAS to improve the positioning errors. The results show that the estimated ionospheric delays can improve the user positioning errors in terms of horizontal and vertical errors up to 0.5 and 1 meter, respectively.
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    Performances of GAGAN Satellite-Based Augmentation System in Thailand Region
    (2020-07-01)
    Sophan, Somkit
    ;
    Phakphisut, Watid
    ;
    Myint, Lin M.M.
    ;
    Supnithi, Pornchai
    The ASEAN IVO project currently supports the research related to GNSS and ionospheric data products for disaster prevention and aviation in low-latitude regions. Satellite-Based Augmentation System (SBAS) is vital to air navigation in many regions around the world. In Thailand, the L1-frequency SBAS corrections can be received from the GPS Aided Geo Augmented Navigation (GAGAN) system which is intended for use over Indian airspace. In this work, we analyze the performances of the GAGAN system in Thailand on quiet and disturbed days in March 2019 by applying the entire corrections received at King Mongkut's Institute of Technology Ladkrabang station. The 95-percent horizontal and vertical accuracies on quiet days are 1.52 and 3.18 meters, respectively. In contrast, on disturbed days they are 1.97 and 3.41 meters, respectively.