A method and apparatus for background decoding of a broadcast satellite-navigation message to maintain integrity of long-term-orbit information used in a Global-Navigation-Satellite System or other positioning system is described. The method may include processing the long-term-orbit information associated with at least one satellite to obtain a first position of a receiver; obtaining at least one portion of broadcast ephemeris transmitted from the at least one satellite; and processing, as a substitute for at least one portion of the long-term-orbit information, the at least one portion of broadcast ephemeris to obtain a second position of the receiver.