Millimeter-wave aircraft landing and taxing system

An aircraft landing or taxiing system, comprising:

• a plurality of radio-frequency (rf) emitters installed at preselected locations on the ground, at least some of the emitters being located to define the outline of a runway;
• means for modulating rf signals transmitted by the emitters, such that each emitter is uniquely identifiable by a different selected modulation frequency;
• a multiple beam antenna system installed in an aircraft and having overlapping receive beams aligned in different directions to provide coverage of a selected field of view from the aircraft;
• a corresponding array of rf processing modules coupled to the multiple beam antenna system, including means for converting any received signals to digital form, in which they may be conveniently processed;
• and
• signal processing means, for further processing signals from the array of rf modules, and including signal analysis means, for separating signals from each rf module into components having amplitudes corresponding to the strengths of signals detected from individual emitters, an further including angle determination means, for determination azimuth and elevation angles of the apparent direction of each detected emitter, whereby the determined azimuth and elevation angles can be used in instruments providing a visual indication of the location and course of the aircraft with respect to the runway;
• wherein the signal analysis means includes a fast Fourier transform (FFT) module, to separate the signals from each receive beam into frequency components, thereby uniquely identifying signal contributions from each emitter on the ground, said fast Fourier transform module generating a set of amplitudes for each of the identified emitters, wherein the angle determination means uses the generated amplitudes to determine the angular direction of each emitter.

A method for providing navigational data to a pilot of an aircraft during landing or taxiing operations, the method comprising the steps of:

• emitting a plurality of radio-frequency (rf) signals from beacons at selected locations on the ground, at least some of the beacons being located to define the outline of a runway;
• modulating the rf signals transmitted by the beacons, such that each beacon is modulated at a different selected frequency and is uniquely identifiable from an aircraft;
• receiving rf signals in the aircraft, using an array of rf antennas having overlapping receive beams aligned in different directions to provide coverage of a selected field of view from the aircraft;
• amplifying any received rf signals and converting them to digital form, in which they may be conveniently processed;
• and
• processing the converted signals, the signal processing step including separating converted signals from each rf module into components having amplitudes corresponding to the strengths of signal detected from individual beacons, and determining azimuth and elevation angles of the apparent direction of each detected beacon, whereby the determined azimuth and elevation angles can be used in instruments providing a visual indication of the location and course of the aircraft with respect to the runway;
• wherein the step of separating converted signals into components includes performing a fast Fourier transformation (FFT) on the converted signals, to separate them into frequency components, thereby uniquely identifying signal contributions from each beacon on the ground, the step of performing a fast Fourier transform including generating a set of amplitudes for each of the emitters, wherein the step of determining azimuth and elevation angles includes using the generated amplitudes to determine the angular direction of each emitter.