Phakphisut, Watid

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Phakphisut, Watid
Alternative Name
Phakphisut, W.
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watid.ph@kmitl.ac.th

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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.
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    Serial belief propagation for the high-rate LDPC decoders and performances in the bit patterned media systems with media noise
    (2011-01-01)
    Phakphisut, Watid
    ;
    Supnithi, Pornchai
    ;
    Sopon, Thanomsak
    ;
    Myint, Lin M.M.
    In this work, we propose to use the serial belief propagation or serial scheduling in the 2-D bit patterned media (BPM) system with media noise. The serial scheduling methods are applied to the random LDPC codes and quasi-cyclic LDPC (QC-LDPC) codes of high code rates. Both are constructed from the progress-edge growth (PEG) algorithm. We compare the performance of the LDPC codes using the serial belief propagation and the conventional belief propagation (BP) decoding. The simulation results show that the serial scheduling provides a faster convergence speed and a better bit error rate performance than the conventional BP in an AWGN channel. The serial belief propagation is also shown to offer the performance gains over the BP decoding for the BPM system with various media noise levels. © 2011 IEEE.
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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.