Amplitude and phase scintillation study at Chiang Rai, Thailand

Ionospheric scintillation is a rapid variation of amplitude and phase in radio signals caused by irregularities in the ionosphere. We have studied the effect of ionospheric scintillations on Global Positioning System (GPS) signals from the low latitude station at Chiang Rai, Thailand, and also studied the occurrence of scintillation for geomagnetic-quiet and -disturbed conditions. Amplitude and phase scintillation are investigated by using the single-frequency GPS Ionospheric Scintillation Monitor (GISM) at Chiang Rai (lat. 19.57°N, Ion. 99.52°E). This system is capable of tracking up to 11 GPS satellites at LI frequency of 1575.42 MHz. The purpose of the GISM receiver is to automatically record scintillation parameters of amplitude and phase at a 50 Hz rate averaged over 60 s. The result shows that the amplitude scintillation can occur with or without phase scintillation but phase scintillation is always accompanied by amplitude scintillation.