Short baseline helicopter positioning radar for low visibility
First Claim
1. A method for determining position of an aircraft with respect to a ground station, comprising:
- transmitting a signal from the aircraft, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency, wherein transmission of each frequency is followed by a time interval of no transmission such that multiple path signals have decreased in amplitude by a predetermined amount;
detecting the signals at an array of sensors disposed on the ground surface in a selected pattern, the array including at least one reference sensor and at least three spaced apart phase difference determination sensors;
determining a difference in phase of the signals between the reference sensor and each of the phase difference determination sensors by determining a relationship between frequency and phase difference between signals detected by the reference sensor and each time difference determination sensor at each of a plurality of frequencies without using a time reference between sensors; and
determining a spatial position of the aircraft from the time differences.
1 Assignment
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Accused Products
Abstract
A method for determining position and orientation of a rotating wing aircraft (e.g. helicopter) with respect to a ground station includes transmitting an electromagnetic signal from the aircraft. The signal includes a plurality of electromagnetic signals, each signal having a different selected frequency. The signal is detected at an array of sensors disposed on the ground surface in a selected pattern. The array includes at least one reference sensor and at least three spaced apart time difference determination sensors. A difference in arrival time of the signals between the reference sensor and each of the time difference determination sensors is determined and a spatial position of the aircraft is determined from the time differences.
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Citations
15 Claims
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1. A method for determining position of an aircraft with respect to a ground station, comprising:
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transmitting a signal from the aircraft, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency, wherein transmission of each frequency is followed by a time interval of no transmission such that multiple path signals have decreased in amplitude by a predetermined amount; detecting the signals at an array of sensors disposed on the ground surface in a selected pattern, the array including at least one reference sensor and at least three spaced apart phase difference determination sensors; determining a difference in phase of the signals between the reference sensor and each of the phase difference determination sensors by determining a relationship between frequency and phase difference between signals detected by the reference sensor and each time difference determination sensor at each of a plurality of frequencies without using a time reference between sensors; and determining a spatial position of the aircraft from the time differences. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining position of an aircraft with respect to a ground station, comprising:
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transmitting a signal from the ground station, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency, wherein transmission of each frequency is followed by a time interval of no transmission such that multiple path signals have decreased in amplitude by a predetermined amount; detecting the signals at an array of sensors disposed on the aircraft in a selected pattern, the array including at least one reference sensor and at least three spaced apart phase difference determination sensors; determining a difference in arrival time of the signals between the reference sensor and each of the phase difference determination sensors by determining a relationship between frequency and phase difference between signals detected by the reference sensor and each time difference determination sensor at each of a plurality of frequencies without using a time reference between sensors; and determining a spatial position of the aircraft from the time differences. - View Dependent Claims (8, 9, 10)
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11. A method for determining position of an aircraft with respect to a ground station, comprising:
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transmitting a signal from the aircraft, the signal comprising a plurality of electromagnetic signals, each signal having a different selected frequency; detecting the signals at an array of sensors disposed on the ground surface in a selected pattern, the array including at least one reference sensor and at least three spaced apart time difference determination sensors, the array deployed from the aircraft prior to landing; determining a difference in arrival time of the signals between the reference sensor and each of the time difference determination sensors; and determining a spatial position of the aircraft from the time differences. - View Dependent Claims (12, 13, 14, 15)
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Specification