Impacts of Ionospheric Scintillations on Dilution of Precision and Positioning Errors

Abstract

Equatorial scintillation impacts negatively on GPS navigation measurements by reducing the number of satellites that are readily available for a GPS receiver to calculate a navigation solution. Ideally, a minimum of four satellites is required to calculate a valid navigation solution. We analyzed GPS data from Ascension Island during the Air Force Research Laboratory (AFRL) campaign of the solar maximum year of 2002 (5–19 March 2002). The study showed that strong scintillations impacted the receiver-satellite geometry, with attendant poor dilution of precisions and positioning errors. On the non-scintillation nights, the GPS receiver showed good tracking capability, as it consistently maintained lock on six to eight satellites, and the GDOP and PDOP values were generally less than 2.2 with lesser positioning errors. In contrast, on the scintillation nights, between 2200 and 2300 UT, the number of satellites that the receiver maintained lock on were consistently reducing to four and in some cases fewer than four. Around this period, the GDOP or PDOP values were higher than 6.0, and significant vertical and horizontal positioning errors were recorded. Equatorial scintillation is capable of adding about 3 metres error to the overall error budget of a GNSS system.