Patent ID: 7499710

Claim:
A method of performing integrity monitoring comprising the steps of: selecting at least one ranging measurement associated with a first ranging source belonging to a first ranging source type; selecting at least one ranging measurement associated with a second ranging source belonging to a second ranging source type; and performing failure detection using the selected ranging measurements associated with the first and second ranging sources to determine whether either of the first or second ranging sources failed, wherein at least one ranging source type comprises a satellite system and at least one ranging source type comprises a land-based wireless communication network and wherein the ranging measurement associated with the first or second ranging source comprises one of a PN phase offset measurement, a pilot phase offset measurement of a pilot signal transmitted by the first or second ranging source, a signal strength measurement of a signal transmitted by the first or second ranging source, a round trip delay between a receiver and the first or second ranging source, a one way delay between a receiver and the first or second ranging source, or an enhanced observed time difference between a receiver and the first or second ranging source.