Study of Ionospheric Scintillation at Low Latitude GPS Stations And Ephemeris Threat Models

摘要

Global positioning system (GPS) is a satellite based navigation system , which is developed by the Department of Defense (DOD) USA. GPS provides 3D position, velocity and time in all weather conditions. GPS position accuracy is limited by several error sources such as satellite ephermies, multipath effect, clock inaccuracies errors, ionospheric&tropospheric errors and relativistic errors. Among them the ionospheric error is the predominant one. Ionosphere scintillations can be limiting the GPS positionalaccuracy. Ionospheric scintillation is low frequency, random perturbations of the amplitude and/or phase of the carrier and code signals caused by very small irregularity structures in the ionosphere. In this paper, ionospheric scintillations are analyzed. For this purpose, data of dual frequency GPS receiver located in Hyderabad, Bangalore, Bhopal are considered. The preliminary results would be useful for developing now/forecasting ionospheric scintillation model over low latitude regionand also Ephemeris treat models.