Low observable radar augmented GPS navigation system
First Claim
1. A low-observable radar altimeter augmented SPS (satellite positioning system) navigation system for use on an aircraft, comprising:
- a SPS receiver for receiving a GPS signal and determining a position therefrom;
an attitude sensor coupled to said SPS receiver, said attitude sensor adapted to determine three dimensional attitude information for said aircraft;
a radar altimeter coupled to said SPS receiver and coupled to said attitude sensor, said radar altimeter adapted to measure an AGL (above ground level) altitude of said aircraft using a radar beam, said radar altimeter coupled to said attitude sensor and adapted to use said attitude information to maintain said radar beam in a substantially vertical attitude with respect to said aircraft to increase the accuracy of said position.
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Accused Products
Abstract
The present invention comprises a low-observable radar altimeter augmented GPS (global positioning system) aircraft navigation system. The system of the present invention includes a GPS receiver, an attitude sensor, and a low-observable radar altimeter. The GPS receiver receives GPS signals and determines a position therefrom. The attitude sensor is coupled to the GPS receiver. The attitude sensor is adapted to receive GPS signals and determine a three dimensional attitude of the aircraft therefrom. The low-observable radar altimeter is also coupled to the GPS receiver and is coupled to the attitude sensor. The radar altimeter is adapted to measure an AGL (above ground level) altitude of the aircraft. The radar altimeter measures the altitude by employing a low-observable radar transmitter slaved to the attitude sensor. The radar altimeter uses the attitude sensor to maintain a radar beam in a substantially vertical attitude (e.g., parallel to the local gravity vector). The system of the present invention uses the AGL altitude to increase the accuracy of the position.
49 Citations
34 Claims
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1. A low-observable radar altimeter augmented SPS (satellite positioning system) navigation system for use on an aircraft, comprising:
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a SPS receiver for receiving a GPS signal and determining a position therefrom; an attitude sensor coupled to said SPS receiver, said attitude sensor adapted to determine three dimensional attitude information for said aircraft; a radar altimeter coupled to said SPS receiver and coupled to said attitude sensor, said radar altimeter adapted to measure an AGL (above ground level) altitude of said aircraft using a radar beam, said radar altimeter coupled to said attitude sensor and adapted to use said attitude information to maintain said radar beam in a substantially vertical attitude with respect to said aircraft to increase the accuracy of said position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A radar altimeter augmented GPS navigation system, comprising:
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a GPS receiver for receiving a GPS signal and determining a position therefrom; an attitude sensor coupled to said GPS receiver, said attitude sensor adapted to determine a three dimensional attitude of an aircraft; a radar altimeter coupled to said GPS receiver and coupled to said attitude sensor, said radar altimeter adapted to measure an AGL (above ground level) altitude of said aircraft using a radar beam, said radar altimeter coupled to said attitude sensor and adapted to use said attitude of said aircraft to maintain said radar beam in a substantially vertical attitude with respect to said aircraft; and a data base coupled to said GPS receiver for storing terrain coordinate information, wherein said terrain coordinate information is blended with said AGL altitude and said GPS position to determine an augmented position having increased accuracy with respect to said GPS position. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method for providing radar altimeter augmented GPS navigation information to enable an aircraft to execute a precision approach and landing independent of ground-based transmitters, the method comprising the steps of:
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a) determining a GPS position by using a GPS receiver receiving a GPS signal and determining said GPS position therefrom; b) determining a three dimensional attitude of an aircraft by using an attitude sensor receiving said GPS signal and determining said attitude therefrom; c) measuring an AGL altitude of said aircraft by using a radar altimeter, wherein said radar altimeter transmits a low-observable radar beam having a low probability of detection; d) maintaining said radar beam in a substantially vertical attitude with respect to said aircraft by using said attitude from said attitude sensor; e) combining said AGL altitude and said GPS position to compute an augmented GPS position having increased accuracy with respect to said GPS position; and f) executing a precision approach and landing by using said augmented GPS position. - View Dependent Claims (22, 23, 24)
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25. A radar altimeter augmented GPS navigation system, comprising:
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a GPS receiver for receiving a GPS signal and determining a position therefrom; an attitude sensor coupled to said GPS receiver, said attitude sensor adapted to receive said GPS signal and determining a three dimensional attitude of an aircraft including said GPS receiver therefrom; a radar altimeter coupled to said GPS receiver and coupled to said attitude sensor, said radar altimeter adapted to measure a radar path length along a radar beam emitted by said radar altimeter, said attitude and said radar path length used to compute an accurate AGL (above ground level) altitude of said aircraft; and a data base coupled to said GPS receiver for storing terrain coordinate information, wherein said terrain coordinate information is blended with said AGL altitude and said GPS position to determine an augmented position having increased accuracy with respect to said GPS position. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification