Investigation of the GPS signals ionospheric correction: Ionospheric TEC prediction over equatorial

The Global Positioning System (GPS) has become a powerful tool for ionospheric studies. The accuracy of coordination data for the Global Positioning System (GPS) receiver by the GPS monitoring station should be increased. The accuracy can be increased by determining the sources of the disturbances that have been produced by all of ionospheric effects. The parameter of ionosphere that produces most of the effects on radio signals is the total number of electrons or Total Electron Content (TEC). Ionospheric Total Electron (TEC) variation with time can be viewed as a stationary random process under quiet conditions. This paper investigate the TEC covering the period from 1 January 2005 at the equatorial. During this period with Kp, Dst, and Ap indices values of reported by the World Data Center (WDC). By modeling this TEC parameter, the evaluation of the ionospheric error and the correction of these ionospheric errors for differential GPS can be done. Dual frequency carrier-phase and code-delay GPS observations are combined to obtain ionospheric observables related to the slant TEC (sTEC) along the satellite-Receiver line of sight (LoS). This research assessing the errors translated from the code-delay to the carrier-phase ionospheric observable by the so- called "Levelling process", applied to reduce carrier- phase ambiguities from the data. The conclusions achieved are the levelled carrier-phase ionosphere observable is affected by a systematic error, produced by code-delay multipath through the leveling procedure. This results in the absolute differential delay and the remaining noise was discarded.