GPS receiver with cross-track hold
First Claim
Patent Images
1. A method of determining position information from GPS satellites comprising the steps of:
- selecting a route to be traveled;
tracking one or more GPS satellites with a GPS receiver mounted for motion along the route;
operating in cross track hold by estimating the route specific cross track information; and
deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track information.
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Accused Products
Abstract
A terrestrial C/A code GPS receiver system derives along track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.
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Citations
47 Claims
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1. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in cross track hold by estimating the route specific cross track information; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track information. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion alone the route; operating in cross track hold by estimating the route specific cross track information from a default value related to the distance representing the expected accuracy of the GPS receiver, or a value related to the maximum expected distance transverse to the centerline of the route to be traveled which is expected to be encountered during motion along the route; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track information. - View Dependent Claims (9)
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10. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in cross track hold by estimating the route specific cross track information from a default value related to a distance representing the expected accuracy of the GPS receiver, or a value related to the maximum expected distance transverse to a centerline of the route to be traveled expected to be encountered during motion along the route; operating in altitude and clock hold by estimating the route specific altitude and satellite time information; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track information by operating in altitude and clock hold by estimating the route specific altitude and satellite time information. - View Dependent Claims (11)
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12. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in cross track hold by estimating the route specific cross track information; operating in altitude and clock hold by estimating the route specific altitude information from a default value related to a distance representing the expected accuracy of the GPS receiver, or a value related to the maximum expected distance transverse to a centerline of the route to be traveled expected to be encountered during motion along the route, and by estimating the satellite time information; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track information by operating in altitude and clock hold by estimating the route specific altitude and satellite time information.
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13. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in cross track hold by estimating the route specific cross track information; operating in altitude hold by estimating the route specific altitude information from a default value related to a distance representing the expected accuracy of the GPS receiver, or a value related to the maximum expected distance transverse to a centerline of the route to be traveled expected to be encountered during motion along the route; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track and altitude information.
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14. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in altitude hold by estimating the route specific altitude information; operating in cross track hold by estimating the route specific cross track information; deriving route specific along track, and satellite time information from the one or more GPS satellites being tracked and the estimated altitude and estimated cross track; and periodically switching from cross track to clock hold to derive updated cross track information from the one or more GPS satellites being tracked. - View Dependent Claims (15, 16)
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17. A method of determining position information from GPS satellites comprising the steps of:
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selecting a route to be traveled; tracking one or more GPS satellites with a GPS receiver mounted for motion along the route; operating in cross track hold by estimating the route specific cross track information from a default value related to a distance representing the expected accuracy of the GPS receiver, or a value related to the maximum expected distance transverse to a centerline of the route to be traveled expected to be encountered during motion along the route; operating in altitude hold by estimating the route specific altitude information; and deriving route specific along track, altitude and satellite time information from the one or more GPS satellites being tracked and the estimated cross track and altitude information. - View Dependent Claims (18)
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19. A method of determining position information from GPS satellites comprising the steps of:
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estimating cross track hold information related to motion of a vehicle transverse to a track; tracking two GPS satellites to derive navigation information therefrom; providing an estimate of vehicle altitude; combining the estimated cross track hold information with the estimate of vehicle altitude and navigation information to derive the position of the vehicle by calculating the position of the vehicle along the track; selectively estimating clock hold information related to satellite time; and combining the estimated clock hold and navigation information to derive updated cross track hold information. - View Dependent Claims (20, 21, 22)
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23. A method of determining position information from GPS satellites comprising the steps of:
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tracking at least two GPS satellites to derive navigation information related to a vehicle in motion along a track; estimating cross track hold information which relates to possible motion of the vehicle transverse to the along track motion; determining along track position information related to the position of the vehicle along the track by combining the estimated cross track and the navigation information.
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24. A method of determining position information from GPS satellites comprising the steps of:
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tracking at least two GPS satellites to derive navigation information related to a vehicle in motion along a track; estimating cross track hold information which relates to possible motion of the vehicle transverse to the along track motion; estimating clock hold information related to satellite time information; determining updated cross track hold information by combining the estimated clock hold and the navigation information; and determining along track position information related to the position of the vehicle along the track by combining the estimated cross track and the navigation information. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. A GPS receiver, comprising:
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means for tracking two GPS satellites to derive navigation information therefrom related to the position of a vehicle; cross track hold means for estimating the deviation of the position, traverse to the direction of travel, of the receiver from a track along which the vehicle is predicted to be in motion; means for estimating a second parameter; and data processing means for combining the navigation information from the two GPS satellites being tracked, the cross track deviation estimate, and the estimated second parameter to derive along track navigation information which relates to the motion of the vehicle along the track. - View Dependent Claims (37, 38)
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32. A GPS receiver comprising:
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means for tracking two GPS satellites to derive navigation information therefrom related to the position of a vehicle; cross track hold means for estimating the deviation of the position, traverse to the direction of travel, of the receiver from a track along which the vehicle is predicted to be in motion; means for estimating a second parameter; data processing means for combining the navigation information from the two GPS satellites being tracked the cross track deviation estimate, and the estimated second parameter to derive along track navigation information which relates to the motion of the vehicle along the track; and selectively operable cross track hold update means, responsive to the means for tracking two GPS satellites, for estimating satellite related time information and for causing the data processing means to combine the navigation information from the two GPS satellites being tracked and the estimated satellite related time information to derive updated cross track hold information. - View Dependent Claims (33, 34, 35, 36)
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39. A method for operating a GPS receiver under adverse satellite signal reception conditions, comprising the steps of:
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creating and using a cross track estimate when only two satellites with adequate geometric coverage are available; and using a fast reacquisition mode to update an along track estimate during brief periods of availability of any additional satellite. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47)
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Specification