摘要:
A method and apparatus for maintaining the integrity of spacecraft based time and position using GPS (11) is disclosed. A GPS receiver is provided with a Receiver Autonomous Integrity Monitor (RAIM) processor (12) and a Kalman filter (14). GPS signals are received from at least four GPS satellites and processed in the GPS receiver to provide time and position information. Periodically, an extended fault vector is formed in the Kalman filter with propagated open-loop position and velocity measurements. The extended fault vector is used to isolate and remove failing GPS satellites.