Wide Area Real Time Kinematics with Galileo and GPS Signals

The main factor limiting the range extension of the Real Time Kinematics technique beyond few tens of kilometers is the differential ionospheric correction between the roving and the nearest reference GNSS station. Such ionospheric correction impedes the real-time ambiguity fixing, and the corresponding accurate navigation at the sub-decimeter level. In this paper, the authors present the recent developments in the application of accurate real-time ionospheric corrections in the context of the future three-frequency systems, such as Galileo and Modernized GPS, regarding previous studies (Hernandez-Pajares et al. 2003b). Indeed, from new datasets gathered in the new three-frequency signal simulator placed at ESTEC/ESA, the feasibility of the Wide Area Real Time Kinematics is confirmed, mostly in single epoch mode (instantaneously): the navigation can be typically performed with few centimeters of error at distances of hundreds of kilometers from the nearest Galileo or Modernized GPS reference station. The new improved strategy adopted (WARTK3.2) includes a no-differenced approach, the ionospheric corrections integrity monitoring, and the capability of the roving user orientation determination with one single antenna at the level of few degrees of error. Moreover, the results obtained with the corresponding strategy adapted to the dual-frequency GPS data confirm both the previous results and the new capabilities of the technique. Particularly, several datasets have been analyzed. Firstly real GPS data have been studied corresponding to an experiment of urban navigation (UNBAR01), performed at Barcelona, Spain, in 2001, with Solar Maximum conditions and local ionospheric perturbations. On the other hand, several three-frequency datasets, simulated in radio-frequency, have been analyzed as well with WARTK-3.2, including a car and an aircraft, moving around the NE of Spain, at distances around 200 km away from the nearest reference site. The results show the feasibility of the long-range real-time accurate positioning with errors of few centimeters, mostly in single-epoch in the new satellite navigation systems.