Introducing the FDI quintuplets [fault detection and isolation]

A method for extending RAIM (receiver autonomous integrity monitoring) has been devised. According to this approach, if one wants to determine whether some SV has a bias and, if so, how much, it should be included as a state to be estimated; under reasonably general conditions, a single SV bias is observable. In a 5-SV snapshot example, both conventional and extended RAIM form five different solutions, with each SV taking its turn in succession as the suspected bias source. Whereas conventional RAIM excludes the suspect SV from the solution, extended RAIM retains it while including the bias as a fifth unknown to be determined