Methods and apparatus for a navigation system with reduced susceptibility to interference and jamming
First Claim
1. A navigation system comprising:
- a reference receiver;
a user receiver;
a global positioning system (GPS) satellite in common view of said reference receiver and said user receiver, wherein said reference receiver and said user receiver receive a carrier ranging signal from said GPS satellite;
a first low earth orbit (LEO) satellite in common view of said reference receiver and said user receiver, wherein said reference receiver and said user receiver are configured to calculate respective first and second measurements of an LEO carrier ranging signal received from said first LEO satellite;
said user receiver configured to receive, via said LEO satellite, said first measurement from said reference receiver and apply said first and second measurements to construct an a priori estimate of a signal phase of said GPS carrier ranging signal received by said user receiver, wherein said a priori estimate is used as the basis of an extended integration of said carrier ranging signal at said user receiver.
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Accused Products
Abstract
A navigation system provides a significant level of protection against all forms of interference or jamming to GPS in a cost-effective way. The system employs a network of ground reference stations and Low Earth Orbiting (LEO) satellites in conjunction with GPS. A common-view ranging geometry to a GPS satellite is established that links a reference station and a user. A second common-view geometry to a LEO satellite between the same reference station and user pair is also established. The ground stations synthesize real-time aiding signals by making carrier phase measurements of GPS the LEO satellite signals. This aiding information is transmitted via the LEO satellites to the user receiver at high power to penetrate ambient jamming. The user receiver locks onto the carrier phase of the LEO satellite, demodulates the aiding information, then applies the carrier phase measurements and the aiding information to enable extended coherent measurements of the GPS signals. The system thereby recovers the GPS signals that would otherwise be lost to the jamming.
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Citations
31 Claims
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1. A navigation system comprising:
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a reference receiver; a user receiver; a global positioning system (GPS) satellite in common view of said reference receiver and said user receiver, wherein said reference receiver and said user receiver receive a carrier ranging signal from said GPS satellite; a first low earth orbit (LEO) satellite in common view of said reference receiver and said user receiver, wherein said reference receiver and said user receiver are configured to calculate respective first and second measurements of an LEO carrier ranging signal received from said first LEO satellite; said user receiver configured to receive, via said LEO satellite, said first measurement from said reference receiver and apply said first and second measurements to construct an a priori estimate of a signal phase of said GPS carrier ranging signal received by said user receiver, wherein said a priori estimate is used as the basis of an extended integration of said carrier ranging signal at said user receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A navigation method wherein a reference receiver and a user receiver receive a carrier ranging signal from a GPS satellite in common view, comprising the steps of:
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measuring, by said reference receiver, a carrier ranging signal from a first LEO satellite in view to produce a first measurement; measuring, by said user receiver, a carrier ranging signal from a second LEO satellite in view to produce a second measurement; said first LEO satellite and said second LEO satellite measuring carrier ranging crosslink signals from each other to produce a third and a fourth measurement, respectively; conveying said first, third, and fourth measurements from said reference receiver and said first and second LEO satellites to said user receiver; using said first, second, third, and fourth measurements to construct an a priori estimate of a phase of the carrier ranging signal from the GPS satellite; and using said a priori estimate as the basis of an extended integration of said GPS satellite signal received by said user receiver. - View Dependent Claims (20, 21, 22)
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23. A navigation method wherein a reference receiver and user receiver receive a carrier ranging signal from a GPS satellite in common view, comprising the steps of:
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measuring, by said reference receiver and said user receiver, a carrier ranging signal from a first LEO satellite in common view to produce first and second measurements, respectively; conveying said first measurement to said user receiver, applying, by said user receiver, said first and second measurements to construct an a priori estimate of a phase of said GPS carrier ranging signal, using said a priori estimate as the basis of an extended integration of said GPS satellite signal received by said user receiver. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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Specification