Effects of the ionised atmosphere on signals from Global Navigation Satellite Systems

Project: Engineering and Physical Sciences Research Council Advanced Research Fellowship 2004-2009

Researcher: Cathryn Mitchell

Global Navigation Satellite Systems (GNSS) can provide position, velocity and time information anywhere on or near the surface of the Earth. The first such system widely available to civilian users is the Global Positioning System (GPS), which has been adopted successfully for many different applications. However, a number of critical problems still remain in using GPS for applications requiring a high degree of accuracy or integrity. These problems originate in uncertainties in the signal's propagation speed and path and can be divided into two areas (i) atmospheric phenomena and (ii) local environment factors. This proposal is concerned with the former area and in particular the effects of the ionised regions of the atmosphere over Europe. The project will use GPS data in a novel imaging technique to create large-scale, four-dimensional maps of electron concentration in the ionosphere. The ionospheric features co-located with regions of signal loss and scintillation will be identified. Complementary measurements of electron and ion temperatures and concentrations will be used to reveal the physical mechanisms responsible for the scintillation. The results will be of interest to the plasma physics community, bringing insight into mechanisms causing ionospheric scintillation. The applicant is fortunate to span the physics/engineering academic interface and the research outcomes will be shared with satellite communications engineers, in particular with those involved with the development of the forthcoming European Galileo System planned to be fully operational in 2008.