METHOD AND APPARATUS FOR DETERMINING AN INTEGRITY INDICATING PARAMETER INDICATING THE INTEGRITY OF POSITIONING INFORMATION DETERMINED IN A GLOBAL POSITIONING SYSTEM

The present invention relates to a method and an apparatus for determining an integrity indicating parameter (e.g. an integrity risk IR or a protection level PL) indicating the integrity of positioning information determined from positioning information signals disseminated from a plurality of space vehicles SAT1, SAT2, SAT3 of a global positioning system. An input parameter (e.g. an alert limit AL or an integrity risk IR) is provided, a plurality of integrity information parameters (σSISA, σSISMA or equivalent, σX, kX) are received, and the integrity indicating parameter (IR; PL) is determined on the basis of the input parameter (AL; IR) and on the basis of a first relation between the integrity indicating parameter (IR; PL) and the input parameter (AL; IR) and the plurality of integrity information parameters (σSISA, σSISMA or equivalent, σX, kX).