Methods and apparatus for a navigation system with reduced susceptibility to interference and jamming

摘要

#$%^&*AU2011265571A120120202.pdf#####METHODS AND APPARATUS FOR A NAVIGATION SYSTEM WITH REDUCED SUSCEPTIBILITY TO INTERFERENCE AND JAMMING ABSTRACT A navigation system (200) provides a significant level of protection against all 5 forms of interference or jamming to GPS in a cost-effective way. The system (200) employs a network of ground reference stations (210) and Low Earth Orbiting (LEO) satellites (222) in conjunction with GPS. A common-view ranging geometry to a GPS satellite (206) is established that links a reference station (210) and a user (202). A second common-view geometry to a LEO satellite (222) between the same reference station (210) 10 and user (202) pair is also established. The ground stations (210) synthesize real-time aiding signals by making carrier phase measurements of GPS and the LEO satellite signals (208, 209). This aiding information is transmitted via the LEO satellites (222) to the user receiver (202) at high power to penetrate ambient jamming. The user receiver (202) locks onto the carrier phase of the LEO satellite (222), demodulates the aiding information, then 15 applies the carrier phase measurements and the aiding information to enable extended coherent measurements of the GPS signals. The system (200) thereby recovers the GPS signals that would otherwise be lost to the jamming. 5857726_1