Ionospheric effects on GPS positioning

Ionospheric scintillation results from a single frequency global positioning system (GPS) receiver have been presented in this paper. Ionospheric scintillation is rapid variation in the amplitude and phase of radio signals caused by irregularities in the ionosphere. Ionosphere contains large amplitude variations over spatial scales from few cm to 100s of km. It is observed that VHF-UHF communications as well as automated navigation and precision positioning via GPS are affected by scintillations. Scintillations do not have major effects on mid latitude regions, but low latitude scintillations are the greatest cause of GPS position errors. In the present work, we study the effect of ionospheric scintillations on GPS signal at low latitude station, Chiang gai, Thailand. The data were analyzed from January 2001 to December 2001. Results show that scintillation has a significant problem at this latitude and position error increases during active scintillation condition, which causes loss of lock on several satellites. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.