Passive aircraft monitoring system
AssigneeHughes Aircraft Company
InventorsMarc Finkelstein, Martin J. Geesaman, Thomas J. Lynch
Life of this patent
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Abstract
A passive aircraft monitoring system (20) receives signals transmitted by an instrument landing system (14, 16) and reflected from aircraft (18). The Doppler shift in the reflected signals is used to calculate the position or velocity of the aircraft. Using the ILS 90 and 150 Hz signals reflected from the aircraft and comparing their magnitude, the altitude and lateral position of the aircraft can also be determined.
Claims22
A method for monitoring aircraft on a runway approach or departure flight path wherein the aircraft are subject to electromagnetic radiation signals of a landing system, the signals having a known frequency and source comprising:
- receiving, at a location offset laterally from the runway, the signals reflected from the aircraft flying along the flight path;
- generating digital samples of the reflected signals received by the receiver;
- performing a Fourier transform on the digital samples, thereby converting the signals to the frequency domain;
- determining the Doppler frequency shift in the converted digital samples;
- and
- calculating an attribute of the aircraft using the Doppler frequency shift of the reflected signals.
A system for monitoring aircraft flying along an Instrument Landing System (ILS) flight path comprising:
- a receiver for receiving ILS signals reflected from aircraft flying along the ILS flight path;
- an analog to digital converter for generating digital samples of the reflected ILS signals received by the receiver;
- a digital signal processor for performing a Fourier transform on the digital samples, converting the signals to the frequency domain;
- and
- a processing unit for determining the Doppler frequency shift in the converted digital samples and calculating an attribute of the aircraft from which the signals are reflected using the Doppler frequency shift.
A method for monitoring aircraft flying along an Instrument Landing System (ILS) flight path comprising:
- receiving ILS signals reflected from aircraft flying along the ILS flight path;
- generating digital samples of the reflected ILS signals received by the receiver;
- performing a Fourier transform on the digital samples, thereby converting the signals to the frequency domain;
- determining the Doppler frequency shift in the converted digital samples;
- and
- calculating an attribute of the aircraft using the Doppler frequency shift of the reflected signals.
A method for determining the groundspeed of aircraft flying along an Instrument Landing System (ILS) flight path comprising:
- receiving ILS marker beacon signals reflected from the aircraft in the ILS flight path;
- comparing the times at which the reflected beacon signals are received to determine the aircraft speed between the respective beacon transmitters.
Dependencies are inferred from the claim text.