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    Item type:Publication,
    Equatorial Plasma Bubble Detection by Support Vector Machine at Chumphon Station, Thailand
    (2022-01-01)
    Thanakulketsarat, Thananphat
    ;
    Supnithi, Pornchai
    ;
    Myint, Lin Min Min
    ;
    Hozumi, Kornyanat
    Equatorial Plasma Bubble (EPB) is a phenomenon in which depletion of plasma density occurs in the ionosphere particularly in the equatorial region. It can degrade the performances of the navigation system and satellite communication. In this work, we analyze EPB based on the very-high frequency (VHF) radar images at Chumphon station, Thailand. Then an EPB detection system using the support vector machine (SVM) technique is developed, and the accuracies of the systems using different kernels: linear kernel, the polynomial kernel, the radial basic functions kernel (RBF), and the sigmoid kernel are compared. Among the different kernels, we find that the RBF kernel gives the highest accuracy in prediction at 86.67 percent.
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    Item type:Publication,
    Study on Effect of Equatorial Plasma Bubble over Real-Time Kinematic Positioning in Bangkok Thailand
    (2022-01-01)
    Thu, Phyo C.
    ;
    Supnithi, Pornchai
    ;
    Myint, Lin Min Min
    ;
    Budtho, Jirapoom
    ;
    Saito, Susumu
    Equatorial plasma bubbles (EPBs) depict local ionospheric irregularity in low-latitude regions which can spread to mid-latitude regions. In this work, we analyzed the effects of the EPBs on the performance of real-time kinematic (RTK) positioning at the short, medium, and long baselines in Bangkok, Thailand. We used the kinematic positioning mode provided by a free and open-source software (FOSS) package called RTKLIB to analyze the positioning errors. It is found that the positioning errors are higher during the disturbance periods and more severe in the long baseline case.