Abstract: System and methods for a ground based millimeter wave imaging system that provides real-time millimeter wave images of an airport to one or more aircraft from one or more ground stations (18). The system includes at least one millimeter wave transceiver (19) that is located in each one or more ground stations. Each at least one millimeter wave transceiver collects real-time millimeter wave images of the airport. At least one image processor (21) is operatively connected to the at least one millimeter wave transceiver, and processes the real-time millimeter wave images of the airport. At least one data link (22) allows communication of information between the one or more aircraft and the one or more ground station. The one or more ground stations transmit the processed realtime millimeter wave images to the one or more aircraft using the at least one link.

Abstract: There is provided an automatic airport information transmitting apparatus comprising: airport-inside-target detecting means for detecting a target inside an airport; target judging means for judging a target moved in a place within the airport, which is required to surveille an aircraft based upon target position information derived from the airport-inside-target detecting means; and transmitting means for transmitting information of the target inside the airport judged by the target judging means to an aircraft which is flying around the airport in a wireless manner. In a relatively small-scaled airport where no controller is present, the automatic airport information transmitting apparatus improves a flight security of aircraft which are flying around the airport and are landing at this airport.

Abstract: The system and method of the present invention provides a record of the performance of an aircraft engine. A plurality of sensors sense engine conditions and generate engine data. A ground data link unit is positioned within the aircraft and receives the engine data. A wideband spread spectrum transmitter that can be part of a transceiver downloads the engine data to a ground based spread spectrum receiver that can be part of a transceiver, and receives the wideband spread spectrum communication signal from the aircraft. It demodulates the wideband spread spectrum communication signal to obtain the engine data.

Abstract: An aircraft including an approach and landing system, including a navigation unit for providing navigation information, a weather radar unit for providing radar information, a processor which receives navigation information from the navigation unit and information from the weather radar unit, the processor unit providing an output representing information concerning the aircraft in accordance with the provided navigation information and radar information, a memory for storing information representing a scene, the processor unit correlating the stored scene information with the output representing information concerning the aircraft to provide a mapped scene, a display unit for displaying the output of said processor and the mapped scene, and a steppable frequency oscillator for providing a signal which is stepped in frequency to the weather radar unit, thereby providing an increased range resolution.

Abstract: A precision approach capable dual differential global positioning system (DGPS) receiver avionics system. The system of the present invention includes a first and a second DGPS receiver. The first and second DGPS receivers are both adapted to interface with an autopilot in an aircraft. The DGPS receivers each determine the position of the aircraft as the aircraft proceeds along a flight path. Both DGPS receivers are further adapted to employ carrier aiding to smooth the code phase measurements used in determining the position of the aircraft. Within a predetermined range along the approach path of the aircraft and when the output of the first DGPS receiver and the output of the second DGPS receiver are proximate within a predetermined distance, the DGPS receivers determine a transition point. After the transition point, the DGPS receivers utilize DGPS carrier phase tracking to determine the position of the aircraft relative to its position at the transition point.

Abstract: An aircraft guidance system uses radar imaging to verify airport and runway location and provide navigation updates. The system is applicable to flight operations in low visibility conditions.

Abstract: A flight control system for an aircraft, particularly for a helicopter receives a number of items of information, especially the position of flight control members of said aircraft, and sends, depending on these items of information, control inputs to controls of the aircraft. The flight control system includes at least one sensor which measures values representative of the flight of the aircraft and computing means which generate, at least from these measured values and from the positions of flight control members, corrected control inputs which are sent to the controls and which enable control of the lateral speed of the aircraft with respect to the ground, without varying the course of the aircraft.

Abstract: An aircraft including an approach and landing system, including a navigation unit for providing navigation information, a weather radar unit for providing radar information, a processor which receives navigation information from the navigation unit and information from the weather radar unit, the processor unit providing an output representing information concerning the aircraft in accordance with the provided navigation information and radar information, a memory for storing information representing a scene, the processor unit correlating the stored scene information with the output representing information concerning the aircraft to provide a mapped scene, a display unit for displaying the output of said processor and the mapped scene, and a steppable frequency oscillator for providing a signal which is stepped in frequency to the weather radar unit, thereby providing an increased range resolution.

Abstract: A passive millimeter-wave imaging system (10) that includes a millimeter-wave camera (12) positioned at the end of an aircraft landing strip (14) to provide an image (20) of the aircraft (16) approaching the landing strip (14) along a landing glidepath (18). The camera (12) broadcasts the image (20) of the aircraft (16) approaching the landing strip (14) to the aircraft (16) and to a control tower (24). With this information, the pilot of the aircraft (16) sees his aircraft's position relative to the glidepath (18), and can make landing adjustments accordingly. Likewise, the tower personnel can monitor the aircraft landing glidepath (18) to insure that the aircraft (16) maintain a safe distance relative to the ground.

Abstract: A passive millimeter-wave imaging system (10) is disclosed that provides a full 360° instantaneous azimuthal field-of-view (54) image of a scene. The imaging system (10) makes use of a spherical Luneburg lens (12) and a series of millimeter-wave direct detection receivers (24) configured in a ring (16) around the lens (12), and positioned at the focal plane of the lens (12). The series of receivers (24) are positioned on a plurality of consecutive sensor cards (14), where each card (14) includes a certain number of the receivers (24). The receivers (24) define a one-dimensional focal plane array with limited obscuration, and thus give a 360° instantaneous field-of-view (54) of a slice of the scene. Processing circuitry (32), including a multiplexing array interface for multiplexing the signals from the receivers (24), are positioned on an outer ring (34) outside of the sensor card ring (16).

Abstract: The invention comprises a mulli-wave radar system for obtaining first target position information of a flying object by capturing and tracking the flying object from a maximum detection distance, a stereo-camera system for taking over the tracking of the flying object in the vicinity of a landing point by acquiring the first target position information of the flying object from the milli-wave radar system, and obtaining second target position information having higher precision than the first target position information, and a controller for managing the first target position information of the milli-wave radar system and the second target position information of the stereo-camera system, controlling the milli-wave radar system to capture and track the flying object to the vicinity of the landing point, and controlling the stereo-camera system to capture and track the flying object at the time of landing of the flying object.

Abstract: An airplane precision approach guidance system and method. The airplane precision approach guidance system includes: (i) GPS landing system (GLS) components (12) for receiving and processing signals from GPS satellites (30) and a GPS ground station (32) and generating a first set of velocities; (ii) an inertial reference system (IRS)(20) for generating a second set of velocities; and (iii) guidance software (24) for generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the generated first and second set of velocities. The airplane precision approach guidance system also includes flight instruments (26) and an autopilot system (28) for receiving and processing the information produced by the guidance software. The guidance software may be executed by a conventional airplane processor, such as the GLS processor, the IRS processor or the airplane's autopilot processor, or by a separate stand-alone processor.

Abstract: A data management system and method that enables acquisition, integration and management of real-time data generated at different rates, by multiple, heterogeneous incompatible data sources. The system achieves this functionality by using an expert system to fuse data from a variety of airline, airport operations, ramp control, and air traffic control tower sources, to establish and update reference data values for every aircraft surface operation. The system may be configured as a real-time airport surface traffic management system (TMS) that electronically interconnects air traffic control, airline data and airport operations data to facilitate information sharing and improve taxi queuing. In the TMS operational mode, empirical data shows substantial benefits in ramp operations for airlines, reducing departure taxi times by about one minute per aircraft in operational use, translating as $12 to $15 million per year savings to airlines at the Atlanta, Georgia airport.

Abstract: An image sensor attached to an aircraft generates an image. The image includes a runway and other objects. The edges within the image are detected and Nav Data is used to predict the coordinates defining the runway. The predicted coordinates and the detected edges are correlated to determine the location of the runway within the image. The location of the runway within the image is then used to determine the lateral and vertical deviation of the aircraft relative to the runway.

Abstract: The present automated vehicle travel path determination system which computes a travel path for a vehicle from an origination point to a destination point based on the operating characteristics of the vehicle as well as phenomena extant in the multidimensional space, which phenomena have an impact on the cost of operation of the vehicle. This vehicle travel path determination system can concurrently consider a plurality of vehicle operating characteristics in selecting the travel path. The travel path is optimized for a weighted selection of a number of cost factors, which weighted selection represents a desired combination of cost factors for the operation of this particular vehicle. This vehicle travel path determination system also considers the time varying nature of the phenomena that exist within the multidimensional space and the impact these time varying phenomena have on the vehicle as it traverses the travel path.

Abstract: A method and apparatus are described for the determination of the height above a landing surface and the rate of descent to the landing surface for a fixed wing or rotary wing aircraft when the aircraft is less than about 100 feet above the landing surface. The invention relies on the time-of-flight measurement of preferably short infrared pulses that are transmitted from the sensing device and reflected back to the sensing device from the landing surface. Multiple sensors can be used for redundancy. For each sensing unit the distance is determined by a conversion of the time-of-flight information into a distance reading. The rate of descent is determined from successive distance determinations. An additional algorithm determines if the rate of descent is excessive for the distance above the landing surface and generates an alarm such as an audible or visual signal.

Abstract: A window-passage detection system has a ground system comprising: a first course generator (3) for generating a horizontal DDM (Differential Depth of Modulation) pattern for defining a horizontal width (25) of a virtual window frame by emitting a first carrier signal and a first side-band signal from a pair of first transmission antennae (6a and 6b), a second course generator (4) for generating a vertical DDM pattern for defining a vertical width (26) of the virtual window frame by emitting a second carrier signal and a second side-band signal from a pair of second transmission antennae (7a and 7b), and a third course generator (5) for generating a longitudinal DDM pattern for defining a longitudinal position (27) of the virtual window frame by emitting a third carrier signal and a third side-band signal from a pair of third transmission antenna (8a and 8b). Pairs of the first to the third transmission antennae (6a to 8b) generate three orthogonal polarization planes.

Abstract: A precision approach capable dual differential global positioning system (DGPS) receiver avionics system. The system of the present invention includes a first and a second DGPS receiver. The first and second DGPS receivers are both adapted to interface with an autopilot in an aircraft. The DGPS receivers each determine the position of the aircraft as the aircraft proceeds along a flight path. Both DGPS receivers are further adapted to employ carrier aiding to smooth the code phase measurements used in determining the position of the aircraft. Within a predetermined range along the approach path of the aircraft and when the output of the first DGPS receiver and the output of the second DGPS receiver are proximate within a predetermined distance, the DGPS receivers determine a transition point. After the transition point, the DGPS receivers utilize DGPS carrier phase tracking to determine the position of the aircraft relative to its position at the transition point.

Abstract: A broadband transmitter element, located at a remote object, transmits a broadband signal at a prescribed transmission time. A broadband receiver element, located at a base platform spaced from the remote object, receives electromagnetic radiation during a reception search window. The broadband receiver element stores information characterizing the broadband signal. A synchronizer synchronizes the broadband transmitter element with the broadband receiver element for timing the transmission and reception. A processing device derives an estimated time of flight for the broadband signal to travel from the remote object to the base platform, and a correlation detector, located at the base platform, identifies the remote object and the arrival time of the broadband signal by correlating the stored information with signals received during the reception search window.

Abstract: An improved precision approach radar (PAR) system using an integrated digital display for displaying the relative position of one or more targets, e.g., aircraft, to a preferred glide path and azimuth course line. A preferred PAR system uses a radar head which emits a pair of scanned radar beams and interprets reflected responses to individually determine aircraft targets, weather patterns and/or obstructions and displays each reflection category as a different pattern, preferably color coded, on an essentially non-flickering monitor.

Abstract: A microwave radio frequency landing system includes an aircraft borne transmitter/receiver (transceiver) and a ground unit. The ground unit comprises a dielectric material lens and a transponder module array. The transceiver transmits pulsed interrogation signals to the ground unit. The dielectric material lens focuses the pulsed signals onto the transponder module array. The transponder modules illuminated by the pulsed signals transmit continuous wave return signals to the aircraft. Each continuous wave return signal comprises four tones, which are used by the aircraft to determine azimuth and glide slope of the aircraft, carried on a microwave carrier. In each transponder module which receives the pulsed signals from the aircraft transceiver, the microwave carrier is phase inverted for the duration of each pulse of the pulsed signals. The phase inversions on the microwave carrier are used by the aircraft to determine the range, velocity and acceleration of the aircraft with respect to the ground unit.

Abstract: Plural light emitting device groups are arranged in the direction perpendicular to the center line of a runway and each of them comprises plural light emitting devices different in light emitting angle from one another. A first controller controls said plural light emitting device groups so that light emitting devices having the same light emitting angle may emit light at the same time and light emitting devices having different light emitting angles may emit light one after another. Plural light receiving device groups are arranged, respectively, so as to correspond to the plural light emitting devices and which receive reflected light from a flying object passing a monitoring space.

Abstract: An aircraft local-area augmentation system that employs a differential global positioning system (GPS) to assist aircraft (102) landing is disclosed. One or more GPS ground stations (120), each including at least two GPS receivers (122) and a datalink transmitter (126), calculate and transmit GPS correction data to an aircraft (102). An aircraft (102) employs a GPS receiver (106) for receiving ranging signals (112) from GPS satellites (108), and a datalink receiver (116) for receiving GPS correction data and other information from a GPS ground station (120). The aircraft (102) further includes a data processor (110) for determining a global position of the aircraft (102) as a function of the aircraft GPS pseudorange data and the GPS correction data. The system minimizes the introduction of non-common errors by the use of double-differencing calculations using multiple combinations of satellite (108) and GPS ground station receiver (122).

Abstract: A system and apparatus for enhancing the satellite based navigation systems which includes providing an aircraft with an interrogating radar for interrogating beacons disposed at a predetermined location in front of a runway wherein the beacons are radar-activated passively powered runway beacons.

Abstract: A system for displaying a landing/taxiing area as an aircraft approaches/taxis that landing/taxiing area. The system includes means on the landing/taxiing area that absorbs radar signals. The remainder of the landing/taxiing area reflects radar signals, and the system includes processors on board the aircraft or in the control tower for translating the signals and the lack of signals into a graphic representation of the landing/taxiing area. The representation changes as the orientation and position of the aircraft changes with respect to the landing/taxiing area. The system can include an autopilot control, head-up displays and memory systems. The system permits surface control by the tower.

Abstract: A radar detection system includes a transmitter and a receiver. The transmitter generates a pulse including a first subpulse generated at a first predetermined frequency and a second subpulse generated at a second predetermined frequency. At least one of the first and second subpulses include a digitally adjusted rise time and fall time, each of the rise time and fall time being separately adjustable independent of the other to provide for the relative lowering of transmission power above and below the first and second predetermined frequencies. The transmitter then transmits generated first and second subpulses at the respective first and second predetermined frequencies, as digitally adjusted in rise and fall time.

Abstract: An apparatus for monitoring the position of objects in a space including a target supervisor, a location supervisor, and a hazard monitoring supervisor. The apparatus can detect and respond to a potential wake-vortex hazard condition. The tracking supervisor receives target data from a sensor, characterizes and tracks selected objects, and provides target outputs having features respective of the selected objects. The location supervisor characterizes and displays features in the space, and provides a location output having the aforementioned features. The hazard monitoring supervisor detects and responds to potential hazard conditions, and provides a notice of such conditions, responsive to the target outputs and the location output. A data logger selectively retains the target outputs, the location output, or both. The position monitoring apparatus has six modes: full operation, non-airport-surveillance-radar, isolation, set-up, adaptation, and simulation.

Abstract: A system for enhancing navigation or surveillance in low visibility conditions is realized by employing one or more ultraviolet radiation sources, a receiver which is capable of producing output signals from which a two dimensional image of the received radiation can be constructed, and a display device for displaying such image. In one preferred embodiment the ultraviolet radiation source is co-positioned with a critical marker such as a runway beacon or hazard beacon. The ultraviolet radiation emanates from the source, preferably modulated to form a repetitive, characteristic signal, propagates through the low visibility atmosphere, and received by the ultraviolet imaging receiver. In another preferred embodiment, an ultraviolet radiation source is placed at or near the ultraviolet imaging receiver, that is, onboard the same vehicle or at the same fixed location. One or more reflectors are co-positioned with the critical markers.

Abstract: An automatic landing system for guiding an unmanned aerial vehicle along a predetermined path to a predetermined point on the ground. The system includes an image processing means resident in the motion compensation processor that computes aerial vehicle parameters. The computed parameters are altitude, changes in altitude, changes in pitch and yaw angles, roll angle and changes thereto, and changes in cross range and down range position. These computations are based on the movement of elements in the video of an imaging sensor onboard the aerial vehicle. The motion compensation processor also measures the distance (in pixels or picture elements) between two beacons placed a known distance apart on either side of the apparent touchdown point. A recovery control processor uses these parameters to compute both desired and actual altitude as a function of range from the vehicle to the apparent point of touchdown and to provide offset error in azimuth from the desired flight path to the landing area.

Abstract: A relative GPS landing system is provided for approach and landing of aircraft where an accurate site survey of the GPS platform is unavailable. Data containing information on all GPS satellites in view is uplinked from a ground station to an aircraft. A relative solution is derived at the aircraft. Based upon the calculated solution, aircraft guidance signals are generated for approach and landing of the aircraft at a desired point.

Abstract: This optoelectronic device is designed to provide assistance in the piloting of an aircraft under conditions of poor visibility, at the final approach stage, during taxiing and at take-off from a runway equipped with an ILS. The device consists of a collimator displaying a reticule symbolizing a runway centerline that is shown to the pilot during flight as well as on the ground, without any break between the in-flight final approach stage and the ground stage of taxiing on the runway. The device takes account of the pilot's off-centered position in the aircraft cockpit.

Abstract: The disclosure is an aircraft landing aid device that includes at least a database containing signatures and positions of reference objects, a sensor picking up signatures of reference objects, means of navigation used to fix the approximate position of the aircraft, means of correlation connected to said means of navigation, sensor and database, that define the vertical and horizontal bearings of the objects picked up by said sensor, and means of fixing the exact position of the aircraft, connected to said means of navigation, sensor and database. It is applicable in particular to airliners, enabling landing in all weather conditions.

Abstract: An aircraft including an approach and landing system, including a navigation unit for providing navigation information, a weather radar unit for providing radar information, a processor which receives navigation information from the navigation unit and information from the weather radar unit, the processor unit providing an output representing information concerning the aircraft in accordance with the provided navigation information and radar information, a memory for storing information representing a scene, the processor unit correlating the stored scene information with the output representing information concerning the aircraft to provide a mapped scene, a display unit for displaying the output of said processor and the mapped scene, and a steppable frequency oscillator for providing a signal which is stepped in frequency to the weather radar unit, thereby providing an increased range resolution.

Abstract: A system for assistance in landing a helicopter and for the detection of electro-magnetic anomalies utilizing helicopter blades as carriers of receiving devices in a wide spectrum of electro-magnetic fields with a predicted sensitivity and resolution far in advance of previous systems.

Abstract: A millimeter wave radar is placed on an aircraft and several radar targets are placed near a runway. The targets are discrete objects, each having a relatively localized radar cross section, a unique signature or a unique range bin, and a position which is accurately known. Targets should be spread over the length of the runway. Radar corner reflectors and active or passive repeaters are preferred. The locations of the radar targets with respect to the runway can be transmitted to the aircraft, or they can be stored on board. On board memory requirements can be reduced by requiring all airports to select one of only a few standard target placement patterns, or even only one. Targets are inexpensive, as are radars whose only precision requirement is in range, and not in azimuth or elevation angles. Range to at least three targets in the radar's field of view is all that is required for an on-board computer to determine the aircraft's location.

Abstract: An aircraft landing system is disclosed in which a differential GPS global positioning system is employed. A ground station, located in the vicinity of one or more landing strips, includes a GPS receiver and a data link transmitter for transmitting GPS correction data and also the global position of two points which define a desired aircraft glide path associated with a particular landing strip. The system further includes aircraft equipment comprising a receiver for receiving the correction data and the global position of the two glide path points, and a GPS receiver. The aircraft equipment further includes a computer for determining a corrected global position of the aircraft as a function of the aircraft GPS range data and the correction data, and subsequently determines the lateral deviation and vertical deviation from the glide path defined by the two glide path points.

Abstract: A passive distance measuring system for aircraft landing or other transportation related or other general usage is disclosed. The passive system operates by measuring the time interval between arrival of a precision sweep scanned signal such as a radio frequency signal at two widely dispersed different signal receptor locations on the aircraft. By knowing the angular sweep velocity of the received signals and the receptor or antenna separation distance on the aircraft, the distance of the aircraft from the scanning source of, for example, radio frequency signals may be computed with appreciable precision. The disclosure includes analog-to-digital signal conversion and modifications of the invention including optical or laser signals in lieu of the preferred microwave radio frequency signals. The disclosure also includes a table of numeric values relating pulse separation time to aircraft range distance and indicates a number of equipment and military environment advantages of the invention.

Abstract: A method and apparatus for aiding a landing aircraft. Three differently-colored beams of laser light are produced and transmitted, one of the beams of laser light being transmitted in a plane containing the direction from which the aircraft is approaching. Another of the beams of light is transmitted on one side of the plane, and the third of the beams of light is transmit on the other side of the plane. The pilot of the aircraft can determine whether the aircraft is on the plane or to the one side or the other by the color of the light the pilot receives. If desired, at least one of the colored laser beams that is transmitted toward one side of the plane can be broken into a plurality of adjacent fan-shaped beams, the light in at least one of the fan-shaped beams being interrupted intermittently.

Abstract: The invention provides a system for determining the spatial position of a moving object and for guiding its movement, which system comprises a triangular arrangement of three light sources attached to the moving object and facing guidance device, electrooptical sensing device comprising an area imaging device and an image processing computer located at a position facing the moving object, there being provided a guidance computer connected to the image processing computer, and radio-communication device for the exchange of signals from and to said moving object. As an alternative the three light sources can be provided at the ground station and the other components of the system being attached to the moving object, there being provided communication device between said station and object. The system is of special value for guiding manned and unmanned aircraft.

Abstract: An all-weather aircraft landing system includes a plurality of ground based passive 90.degree. dihedral reflectors for producing two-bounce reflected signals without ground reflections, and an airborne radar system which may transmit and receive "same sense" circularly polarized radiation, while completely rejecting "opposite sense" polarization returns or else utilizing them to indicate weather conditions. Radar clutter from objects such as rain, buildings and trees which produce opposite sense reflections are rejected by the "same sense" receiver or switched to an "opposite sense" receiver to provide weather/obstacle condition information. By properly orienting a plurality of 90.degree. dihedral angle reflectors of a particular size in a predetermined array pattern and tilt-angle adjacent a runway, the reflections from airborne radar signals are processed and displayed to provide a visual means for determining glide slope deviation and approach vector of the landing aircraft.

Abstract: A method of using a method for navigating and updating of navigation for aircract under utilization of sensor image processing and reference store data, for purposes of automatic or assisted landing is disclosed.

Abstract: Optical guidance system for the night landing of aircraft on a landing area along a determined approach path, which comprises two horizon reference luminous bars (1, 2) disposed in alignment with each other in a horizontal direction substantially perpendicular to the approach path, and two azimuth overshoot indicating lamps, respectively to the left (5) and to the right (6), located at the outer ends of the pair of horizon reference bars and provided with masks (8) in order that they can only be seen by the aircraft if the latter overshoots the approach path in azimuth to the left and to the right respectively.

Abstract: A pattern change mechanism is provided for use with a lighting fixture. The mechanism includes a plurality of blocking members for blocking light directed by the reflector of the lighting fixture toward a target surface, means for moving the blocking members to achieve small, medium and large patterns of light on the target surface. The moving means includes a rotation member, drive means, actuator means linked to the blocking members and a handle for rotating the rotation member to thereby effect movement of the blocking members through the drive means and actuator means.

Abstract: A spectral analyzer and direction indicator system (10) is disclosed and includes optical channels (20,30,40) for providing detected optical information indicative of incidence direction and spectral content of incident radiation. Each optical channel includes a reflector element (11,17,23) having a non-ruled section (11a, 17a, 23a) and a spectrally dispersing ruled section (11b, 17b, 23b); an analytical optical system (13,19,25); and a detector array (15,21,27). For each reflector element the non-ruled section is tilted in one or two directions relative to the ruled section. The disclosed spectral analyzer and direction indicator system is advantageously utilized as an aircraft based sensor in an aircraft landing system having ground based lasers (29L, 29R, 33L, 33R, 37L, 37R) directed into the landing approach path.

Abstract: A portable siting system particularly useful for siting a portable localizer for a collocated approach guidance system for aircraft utilizes a laser range finder in conjunction with a shaft encoder to determine the distance between the localizer and two arbitrary points along a runway center line as well as the azimuth offset between the two points. A microprocessor is used to compute the number of degrees the antenna of the localizer must be rotated so that its beam intersects the extended runway center line at a predetermined point based on trigonometric computations performed on the two measured distances and the measured angle.

Abstract: A method of and apparatus for determining the actual lateral deviation from the centerline of a runway of an aircraft located outside the normal region covered by a glideslope beam is disclosed. The method comprises the steps of scaling a geometrically developed estimated lateral deviation value (Y.sub.estimate) with a compensation factor (K) and passing the result through a complementary filter. The complementary filter produces an estimated lateral deviation rate value (Y.sub.estimate) that is divided into the actual lateral deviation rate value (Y.sub.actual) produced by the inertial navigation system of the aircraft. The result of the division is the compensation factor (K) that is used to scale the geometrically developed estimated lateral deviation value. Preferably, the compensation factor is filtered by a first order lag filter prior to being used to scale the geometrically developed estimated lateral deviation value.

Abstract: A guidance system for landing an aircraft is described which uses a source of signals identifiable with the aircraft and a ground station which is linked to the aircraft. Specifically, the ground station includes a receiver which is connected to one or more pairs of antennas having a fixed, overlapping, directional sensitive pattern symmetically located relative to the center of the landing path, a receiver and a processor for measuring the relative sensitivity of the signals received at the antennas and for using the relative signal intensity to determine the location of the aircraft relative to the center of the landing path.

Abstract: Apparatus for guiding an aircraft along the center line of a runway at rollout touchdown. A rollout predict path command is generated in accordance with a first path segmentY.sub.1 =T.sub.1 (Y.sub.m +Y.sub.u)(1-e.sup.-t /Ti)-Y.sub.m t+Y.sub.ion engaging rollout mode, which path segment transitions to a second path segmentY.sub.2 =Y.sub.1 e.sup.- (t-to/T.sub.1)at a given elapsed time t.sub.o, where T.sub.1 is a predetermined time constant, Y.sub.i is an initial value of lateral displacement on rollout engagement, Y.sub.i is the time derivatives threeof, Y.sub.M is a predetermined maximum lateral displacement rate, and t is the elapsed time. The predict path command signal is combined with a rate signal derived from a localizer position estimate to produce an error signal for commanding a rudder deflection to align the aircraft with the center line of the runway.

Abstract: The detection, by doppler frequencies in reflected wave energey, of an obt, such as an obstruction on a landing surface approached along a path at a shallow angle to the surface, using doppler frequencies returned from a fixed range. The frequencies returned by the surface and the obstruction are distinguished by their relation to a threshold frequency determined by the velocity along the path and the angle. Returns from the surface as the angle of incidence at the fixed range increases from the initial normal angle of incidence are minimized by selection of the carrier frequency, and clutter is rejected by ignoring a return at the fixed range that does not correspond to a subsequent return at a nearer range.

Abstract: A system for landing aircraft during low visibility includes a number of millimeter wave sources in or near the runway light housings radiating millimeter wave beams along the runway. An airborne millimeter wave camera includes a millimeter wave lens that focuses the image of the millimeter wave sources upon a hemispherical detector array that provides signals processed to create an image of the millimeter wave sources corresponding substantially to the visible image perceived by a landing pilot when observing the runway light pattern during good visibility conditions.