Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
1998-04-28
2001-02-06
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C340S947000, C340S972000, C701S016000
Reexamination Certificate
active
06185486
ABSTRACT:
TECHNICAL FIELD
The present invention relates to air vehicle landing/takeoff area mapping systems and methods.
BACKGROUND ART
Heavy fog and other reduced visibility weather conditions make aircraft landings and takeoffs difficult for the pilot. Presently, there are sensor systems on aircraft that attempt to alleviate this problem. Forward Looking Infrared (FLIR) sensors can enhance night time viewing of the runway ahead; however, FLIR sensing is obscured by heavy fog. There is also the Instrumented Landing System (ILS), which utilizes Ultra High Frequency (UHF) technology, to assist the pilot in landing an aircraft during reduced visibility conditions. Still, ILS has shortcomings. ILS does not provide a real-time processed runway outline on a cockpit display device. ILS loses its effectiveness at altitudes less than 100 feet above the runway, where visibility may still be impaired by dense fog. ILS only assists within limits in aircraft landing operations, and is not useful in aircraft takeoffs. Further, ILS may lose effectiveness due to multipath signals, such as those from other nearby runways, aircraft, and/or reflections from buildings and all other structures and outcroppings of the general locale.
U.S. Pat. Nos. 4,940,986 issued to Huguenin and U.S. Pat. No. 5,351,077 issued to Lee et al. describe runway mapping systems. Both of these patents describe the use of power sources on known airport features. The power sources radiate frequency modulated (FM) and amplitude modulated (AM) millimeter wave signals, respectively. A video detection sensor camera uses a lens array to focus an image of the power sources onto a receiver array of a large number of receiving sensors. Thus, the relative locations in the array of the particular sensor or sensors outputting received signal power is indicative of the relative locations of the external power sources. Only aircraft landings are addressed by these two patents.
A primary disadvantage associated with existing runway mapping systems, including those systems which utilize AM signals with a corresponding camera-based receiver array on the aircraft, is the fact that the transmitters and the receiver array are complex and costly. Potential ambiguities introduced via aircraft motion-induced Doppler frequency shifts necessitate a complicated receiving and data processing system, which may still be prone to residual errors in identifying particular locations of emitting sources.
Passive systems that rely only on terrain intrinsic emissivity, in which active emitting sources are absent, are disadvantaged relative to systems employing active emitters by: (1) low emission intensities, which are additionally and markedly attenuated by non-ideal weather conditions, such as fog: and (2) inherently low contrast between the different terrain features, such as runway tarmacs versus grass turf.
DISCLOSURE OF THE INVENTION
It is, therefore, an object of the present invention to provide an improved air vehicle landing/takeoff area mapping system and method capable of takeoff and landing assistance that is functional in reduced visibility weather conditions.
It is another object of the present invention to provide an air vehicle landing/takeoff area mapping system utilizing transmitter and receiver components of relatively inexpensive construction.
In carrying out the above objects and other objects and features of the present invention, an air vehicle landing/takeoff area mapping system is provided. The system comprises a plurality of transmitters located in the landing/takeoff area. Each transmitter propagates a signal having a signal frequency indicative of transmitter location. A receiver located on the air vehicle is capable of scanning the landing/takeoff area. The receiver processes a received transmitter signal to produce an output based on the received transmitter signal frequency. Control logic processes a sequence of receiver outputs to produce an image of the landing/takeoff area on a display device within the air vehicle. The image assists the pilot or operating crew during landings and/or takeoffs, as desired.
Preferably, each transmitter has a substantially hemispherical antenna field pattern. Further, the propagated signals are preferably continuous wave signals, and are microwave band or millimeter waves.
Still further, in a runway embodiment, the plurality of transmitters include first transmitters and second transmitters. The first transmitters are located along the first side of the runway. Each first transmitter propagates a signal with a distinct signal frequency relative to the other first transmitters. The second transmitters are located along the second side of the runway. Each second transmitter propagates a signal with a distinct signal frequency relative to the other second transmitters.
Preferably, the receiver further includes a first stage for receiving the propagated signals, and at least one frequency down conversion stage connected to the first stage. A channelizer for frequency channelizing the signals after frequency down conversion is coupled to the down conversion stage or stages. The channelizer has a separate output for each channel; the control logic receives and processes the outputs.
Further, in a preferred embodiment, a storage medium has information stored thereon representing pre-assigned transmitter locations based on signal frequency. The control logic produces the landing/takeoff area image further based on the stored information.
Further, in carrying out the present invention, an air vehicle landing/takeoff area mapping system comprising a plurality of transmitters, a receiver, a display device, and control logic is provided. The control logic processes receiver information including a sequence of receiver outputs, corresponding transmitter azimuth scan angles, and corresponding transmitter elevation scan angles to produce an image of the landing/takeoff area on the display device. Preferably, the control logic further processes air vehicle avionics information including altitude, heading angle, pitch angle and/or other navigational information to produce the landing/takeoff area image on the display device.
Still further, in carrying out the present invention, a method of mapping an air vehicle landing/takeoff area comprises propagating a plurality of signals from a corresponding plurality of locations in the landing/takeoff area, scanning the landing/takeoff area from an air vehicle to receive the signals, processing each received signal to produce an output based on the received signal frequency, and processing a sequence of outputs to produce a landing/takeoff area image.
The functional advantages accruing to the present invention are numerous. Embodiments of the present invention provide systems and methods for air vehicle landing/takeoff area mapping which are capable of assisting the pilot or operating crew in both takeoffs and landings. Further, embodiments of the present invention may be constructed with relatively inexpensive components because the propagated signal information may advantageously be the frequency of an unmodulated transmitter signal. Still further, embodiments of the present invention may advantageously employ a strictly passive receiver on the aircraft, which may be particularly advantageous in military applications. The passive receiver does not support the enemy foe to home in on the aircraft.
While embodiments of this invention are illustrated and disclosed, these embodiments should not be construed to limit the claims. It is anticipated that various modifications and alternative designs may be made without departing from the scope of this invention.
REFERENCES:
patent: 3671963 (1972-06-01), Assouline et al.
patent: 3952308 (1976-04-01), Lammers
patent: 4890110 (1989-12-01), Kuwahara
patent: 4940986 (1990-07-01), Huguenin
patent: 5047783 (1991-09-01), Hugenin
patent: 5202692 (1993-04-01), Huguenin et al.
patent: 5218360 (1993-06-01), Goetz et al.
patent: 5351077 (1994-09-01), Lee et al.
patent: 5483241 (1996-01-01), Waineo et al.
patent: 5593114 (1997-01-01), Ruhl
pat
Labounsky Alexander
Schneider Stanley
Brooks & Kushman P.C.
Gibson Eric M
McDonnell Douglas Corporation
Zanelli Michael J.
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