System and method for generating precise position determinations
First Claim
1. A method of resolving integer wavelength ambiguities associated with phase measurements made for GPS carrier signals transmitted by GPS satellites, the method being used with an aircraft on a final approach trajectory to a runway, the method comprising the steps of:
- positioning one or more pseudolites each at a fixed known location in front of the runway below the final approach trajectory of the aircraft;
with the one or more pseudolites, transmitting one or more pseudolite carrier signals;
with a mobile GPS receiver system mounted on the aircraft;
receiving the transmitted one or more pseudolite carrier signals and the transmitted GPS carrier signals;
making phase measurements for the received one or more pseudolite carrier signals and the received GPS carrier signals at measurement epochs while the aircraft is on the final approach trajectory, there being an integer wavelength ambiguity associated with the phase measurements made for each of the received GPS carrier signals;
determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs; and
resolving the integer wavelength ambiguities in response to the phase measurements, the known location of each of the one or more pseudolites, and the determined lines of sight to the GPS satellites.
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Accused Products
Abstract
A GPS system and method for generating precise position determinations. The GPS system includes a ground based GPS reference system which receives with a reference receiver GPS signals and makes phase measurements for the carrier components of the GPS signals. The GPS reference system then generates and broadcasts an initialization signal having a carrier component and a data link signal having a data component. The data component of the data link signal contains data representing the phase measurements made by the reference receiver. The GPS system also includes a GPS mobile system which receives with a mobile position receiver the same GPS signals as were received by the reference system. In addition, the GPS position receiver receives the data link and initialization signals broadcast by the reference system. The GPS position receiver then makes phase measurements for the carrier components of the GPS signals during and after an initialization period and makes phase measurements for the initialization signal during the initialization period. In response to the phase measurements made by both the reference receiver and the position receiver during the initialization period, the position receiver generates initialization values representing resolution of the integer ambiguities of the received signals. In response to the initialization values and the phase measurements made by both the receivers after the initialization period, the position receiver generates precise position determinations to within centimeters of the exact location.
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Citations
25 Claims
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1. A method of resolving integer wavelength ambiguities associated with phase measurements made for GPS carrier signals transmitted by GPS satellites, the method being used with an aircraft on a final approach trajectory to a runway, the method comprising the steps of:
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positioning one or more pseudolites each at a fixed known location in front of the runway below the final approach trajectory of the aircraft; with the one or more pseudolites, transmitting one or more pseudolite carrier signals; with a mobile GPS receiver system mounted on the aircraft; receiving the transmitted one or more pseudolite carrier signals and the transmitted GPS carrier signals; making phase measurements for the received one or more pseudolite carrier signals and the received GPS carrier signals at measurement epochs while the aircraft is on the final approach trajectory, there being an integer wavelength ambiguity associated with the phase measurements made for each of the received GPS carrier signals; determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs; and resolving the integer wavelength ambiguities in response to the phase measurements, the known location of each of the one or more pseudolites, and the determined lines of sight to the GPS satellites. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of resolving integer wavelength ambiguities associated with phase measurements made for GPS carrier signals transmitted by GPS satellites, the method comprising the steps of:
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positioning one or more pseudolites each at a fixed known location with respect to a reference coordinate system; with the one or more pseudolites, transmitting one or more pseudolite carrier signals; with a mobile GPS receiver system; receiving the transmitted one or more pseudolite carrier signals and the transmitted GPS carrier signals; making phase measurements for the received one or more pseudolite carrier signals and the received GPS carrier signals at measurement epochs while a large angular change in geometry occurs between the mobile GPS receiver system and the one or more pseudolites, there being an integer wavelength ambiguity associated with the phase measurements made for each of the received GPS carrier signals; determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs; and resolving the integer wavelength ambiguities in response to the phase measurements, the known location of each of the one or more pseudolites, and the determined lines of sights to the GPS satellites. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of making position determinations for a mobile GPS receiver system mounted on an aircraft on a final approach trajectory to a runway, the method comprising the steps of:
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positioning one or more pseudolites each at a fixed known location in front of the runway below the final approach trajectory of the aircraft; with the one or more pseudolites, transmitting one or more pseudolite carrier signals; with a GPS reference system; receiving GPS carrier signals transmitted by GPS satellites at a fixed known reference location with respect to the reference coordinate system; transmitting reference phase information associated with the GPS carrier signals received with the GPS reference system; with the mobile GPS receiver system; receiving the transmitted one or more pseudolite carrier signals, the transmitted GPS carrier signals, and the transmitted reference phase information; making phase measurements for the one or more pseudolite carrier signals and the GPS carrier signals received with the mobile GPS receiver system at measurement epochs during an initialization period while the aircraft is on the final approach trajectory and making phase measurements for the GPS carrier signals received by the mobile GPS receiver system at measurement epochs after the initialization period while the aircraft is still on the final approach trajectory, there being an integer wavelength ambiguity associated with the phase measurements made for each of the GPS carrier signals; determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs during and after the initialization period; resolving the integer wavelength ambiguities in response to (A) the phase measurements made at the measurement epochs during the initialization period, (B) the known location of each of the one or more pseudolites, (C) the reference phase information received during the initialization period, and (D) the determined directions to the GPS satellites at the measurement epochs during the initialization period; and computing positions for the mobile GPS receiver system with respect to the reference coordinate system at the measurement epochs after the initialization period in response to (A) the resolved integer ambiguities, (B) the phase measurements made at the measurement epochs after the initialization period, (C) the reference phase information received after the initialization period, and (D) the determined lines of sight to the GPS satellites at the measurement epochs after the initialization period. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification