Ionospheric Effect in Instantaneous Positioning

GENDE M.; RADICELLA S. M.; NAVA B.; BRUNINI C.

San Diego

Congreso; Institute of Navigation National Technical Meeting; 2003

Institute of Navegation

Since May 2000, after removal of SA, GPS accuracy fornavigation purposes has improved by one order of magnitudeand the ionosphere has become the most important source oferror in positioning calculation. The GPS includes aionospheric model (ICA) in order to mitigate the ionosphericeffect. Taking into account that the intentional degradationintroduced by the SA was at least 10 times bigger than anyother error, a systematic evaluation of the performance of theionospheric model using GPS data was never carried out.This paper examines ICA capability to improve the accuracyconfidence level for point positioning under differentgeographical conditions, different local times and seasons,during a period of high solar activity (year 2001). Thecomparison among uncorrected raw data, ionosphere-freelinear combination and ionosphere-corrected solutions areshown and discussed. The single epoch positioning analysisare done using 30 seconds sample rate data of all visiblesatellites from a dozen of stations located in differentgeomagnetic latitudes