Although GNSS systems now underpin a significant part of modern infrastructure, such as financial markets, telecoms, power generation and distribution as well as transport and emergency services, they suffer from a number of known vulnerabilities. One such shortcoming relates to an ionospheric disturbance known as scintillation. The phenomenon of scintillation is familiar to most people through the twinkling of star light as it crosses the atmosphere. Ionospheric scintillation causes amplitude and phase variations on signals from GNSS satellites when they cross the ionised upper atmosphere (the ionosphere). Currently, GNSS receivers are not robust against radio scintillation; effects range from degradation of positioning accuracy to the complete loss of signal tracking. During scintillation events, required levels of accuracy and continuity, as well as availability, may not be met, thus compromising commercial operations, such as maritime navigation, geophysical exploration and airplane navigation during airport precision approach. The project will quantify the problem of ionospheric scintillation over the forthcoming solar maximum (2010-2013) and develop algorithms to reduce the impact on the users. The research will lead to improved GNSS receiver design that will enable robust performance of receivers that are compromised by effects of the natural environment through ionospheric scintillation.