Ambiguity resolution on ionospheric gradient estimation and detection

For safety-of-life applications, such as landing an aircraft, the detection of ionospheric gradients is important both for the integrity of single frequency GBAS users as the availability for dual frequency users. In this paper an ionospheric gradient monitor is proposed, based on carrier phase observations. Carrier phase observations are very precise, but ambiguous. Although in aviation carrier phase ambiguity resolution is not yet commonly accepted, this research investigates whether it is possible to solve the ambiguities with acceptable success-rates in order to estimate and detect ionospheric gradients.