Abstract: An apparatus and method of canceling a flight plan of an aircraft to facilitate release of an IFR airspace to other aircraft and for communicating the location of a downed aircraft during emergencies. A controller receives and analyzes positioning signals transmitted from know locations to determine the location of the aircraft periodically. Upon arrival of the aircraft at its destination, the controller calls the air traffic controllers to cancel the flight plan. In the event of an emergency, the controller calls the air traffic control center to report the emergency and the location of the aircraft with high accuracy to improve search and rescue operations.

Abstract: A method of passive ranging and geolocation of multiple emitters by a single detection platform. Two independent emission sequences support formulation of two independent algebraic equations involving a triangular arrangement of platform and emitters. One sequence constitutes an interrogation signal by one emitter and a transponded or reflected signal from another. A second emission sequence constitutes the reversed order of emitters from those of the first emission sequence. The method utilizes the steps of measuring the time difference of arrival at the platform of signals having travelled the direct path and the transponded or reflected paths, and measuring the angles of arrival of received signals for each independent emission sequence. A series of steps computing ranges and angles based on prior measurements provide a set of desired ranges and angles identifying the relative positions of the emitters relative to the platform.

Abstract: Apparatus is provided in an aircraft to convert signals from a Universal Navigation System such as LORAN to signals compatible with the standard Omni Bearing Selector (OBS) in the aircraft. The apparatus allows a visual bearing to any destination to be provided for the navigator.

Abstract: A navigation system comprising a relative positioning system (RPS) with dead reckoning and map matching and an absolute positioning system (APS) is provided and operated in such a manner that APS position information is used for updating RPS position and contour of equal probability (CEP) information as required. The APS may comprise a Loran-C or a global positioning system (GPS). Different criteria are used for resetting the RPS depending on whether or not the navigation system comprises a Loran-C or a GPS due to the different levels of precision of the Loran-C and the GPS. When the RPS is reset or updated, it is updated to the current APS position with its offset, if any. Its contour of equal probability (CEP) may also be adjusted.

Abstract: A navigation system for use on an automobile, for example, has a GPS positioning device for determining a present position thereof from radio waves transmitted from GPS satellites, and a stand alone type positioning device including an direction sensor and a speed sensor, for determining a present position thereof from direction data from the direction sensor and speed data from the speed sensor. A data processor selects data from the GPS positioning device or data from the stand alone type positioning device.

Abstract: A navigation apparatus for vehicles has a display device for displaying map information. On the screen of the display device, a current position of the vehicle on which this navigation apparatus is mounted is displayed. Also, a route to a preset destination starting from the current position is displayed at the maximum length.

Abstract: The disclosure relates to methods and apparatus for separating radio signals arriving from different directions and for multiplexing signals intended for receivers dispersed in different directions. The methods and apparatus employ a plurality of antennas with spacing and individual feedline characteristics designed so that a modulation is imparted to each of a plurality of incident signals, for receiving antennas, and radiated signals for transmitting antennas, the modulation level of each signal being determined by the direction of propagation of the signal and by the spacing between antenna pairs. Accordingly, the orientation of lines connecting pairs of antennas as well as the spacing between antennas are set to inhibit the modulation in a particular direction, or to strip a particular modulation off a signal incident from a selected direction.

Abstract: The method of precise position determination, in particular for geodetic positioning by means of carrier-frequency phase-difference measurement on GPS satellites, uses a double difference (.DELTA..phi..sub.12.sup.nm (k)) of a measured phase values, forms an initial solution for a position vector (x.sub.jc) by means of a compensation calculation, and actual phase ambiguities (x.sub.jN) and then integer alternative phase ambiguities (x.sub.jA).A rapid reduction in the number of alternative phase ambiguities (x.sub.jA) to be processed and automatic statistical protection of the results is achieved by means of special statistical selection tests, using a corresponding cofactor matrix (Q.sub.xxj) and an a posteriori rms error (m.sub.0s) of the initial solution.In this way, the required number of satellites (4 to 5) observed and the observation duration (a few minutes) can be reduced considerably, likewise the computer cost. Operator decisions are eliminated.

Abstract: A personal security system and process for use thereof wherein customers of a security service are provided with personal transmitters capable of selectively transmitting one or more radio signals at a desired frequency, the signals representing the particular character of service that is desired. A number of antenna/transmitters are located in evenly spaced relation in the geographical area and correspond to a computer grid work of the geographical area. The antenna/transmitters receive signals having X and Y axes from the personal transmitters, amplify the signals and transmit them to signal processing equipment. The signal processing equipment includes an automatic direction finding circuit capable of receiving the X and Y axes components of the personal transmitter signal and the vertical elevation of the signal in order to yield an ADF signal output reflecting the location of the signal.

Abstract: The present invention is an improved position tracking system utilizing at least three cw transmitting stations generally symmetrically disposed about an area of interest, and also including a mobile receiving station receiving the transmitted signals, converting the received signals to a common frequency, and comparing the phase difference between the converted signals to produce and output signal indicating the location of the mobile station relative to any desired point or points in the area of interest.

Abstract: Position detection methods and apparatus include transmitters, coupled to each object to be tracked, for transmitting signals uniquely identifying each transmitter. Receivers disposed at known locations receive the transmitted signals and generate received signals representative of the transmitted signals. Arrival-time elements, responsive to a selected zero-crossing or other event in each received signal, determine the respective arrival time of each transmitted signal at each receiver. A processor calculates differences in arrival times of the transmitted signals at each receiver, and determines the spatial position of each object with respect to the known locations of the receivers.

Abstract: A radio navigation system including:a means to determine, at a point (M.sub.1) of the trajectory of a moving body to be localized, the speed vector of said moving body and, possible, the "n" order derivatives of said speed vector (with n>1),a means to perform at least three successive measurements of distance, respective between a geodesic point at the ground and three successive positions (M.sub.1, M.sub.2, M.sub.3) of said moving body,a means to computer the position (M.sub.3) of said moving body by resolving a system of equations from the results thus obtained, expressed in one and the same reference system.

Abstract: In a Traffic Alert and Collision Avoidance System (TCAS), response to interrogations can result in normal, multipath (image), and mixed multipath (potential image) tracks. The method for reducing the number of false tracks includes the steps of selecting a track to be updated from an existing track list. The selected track has the shortest measured range within the highest priority category track. A reply which has not yet been utilized is selected which has parameters which are within predetermined windows of the selected track parameters. (The predetermined windows are equal to or smaller than the windows for lower priority targets.) The selected track is updated using .alpha..beta..gamma. range squared filter, and the selected reply is marked as used. After all tracks are updated, the unused replies are tested to generate new tracks. Then all the tracks are examined to insure that predetermined track category criteria are met, otherwise the track is recategorized.

Abstract: A navigational aid comprises a housing with a flat, transparent liquid crystal display. The display is flat and flush with the bottom of the housing, to allow the aid to be placed flat on a map or chart. The aid is microprocessor controlled and accepts plug in memory modules, which contain information relating to an area through which a craft, for example, an aircraft, is to be navigated. The display generates cursors which can be superimposed on the map. The aid can display graphically the progress of the craft, superimposed on the map, on the basis of input data supplied by the user. Alternatively, the cursors can be moved to measure the distance beteen points on the map.

Abstract: The invention disclosed herein is directed to a method and apparatus which employs a spread-spectrum based radiolocation system, using hand-held receiver units and fixed-position reference transmitters, to determine distance and direction between a golfer and key locations on a golf course, such as the distance and direction to a particular pin. The plurality of timing reference transmitters which are located throughout the vicinity of the golf course broadcast a spread-spectrum ranging signal consisting of a radio-frequency carrier directly modulated by a periodic pseudo-noise (PN) coded or similar sequence. Each transmitter broadcasts at the same RF signal but a unique PN-coded sequence is assigned to each transmitter. Golfers are provided with the hand-held receiving unit which receives the transmitter spread-spectrum signals and which synchronizes to the spread-spectrum signals in order to obtain range estimates to a selected set of reference transmitters.

Abstract: According to a target locating method and system, each of a plurality of sensing stations, for example HFDF sensors, senses a nominal value of a predetermined measurement variable such as a bearing, differential times of arrival, etc., relating the location of a potential target in a target area to the location of each respective sensing station. Error models associated with each sensing station, along with the nominal measured variable for each sensing station, are transmitted to a central data collector. A central processor receives the collected data and directs a monitor to display a representation of the target area. The invention also provides a method for estimating the position of the target based on the nominal measurements of the location variable and also on the error models for each sensing station. The target area is divided into a grid of target area segments.

Abstract: To supplement an electronic navigation system, for example associated with a locating map storing possible paths of a vehicle, two path sensors are provided, one (10) evaluating vehicle operating data and distance traveled, and the other (12) evaluating position of the vehicle with respect to the geomagnetic field. In accordance with the invention, and in order to eliminate drift errors of the vehicle operating sensor (10) and disturbances of the magnetic field sensed by the magnetic field sensor, the output signals from the vehicle operating sensor are differentiated to eliminate long-term drift, and the output signals from the field sensor are integrated to eliminate short disturbances, both the differentiation as well as the integration steps being carried out with respect to distance traveled and not with respect to time. The respectively differentiated and integrated signals are then combined in an adder (28) for application to a course or navigation computer of standard construction.

Abstract: A combined navigational and display system for a person including a helmet carrying apparatus for communication, storage and processing of information and for the visual display of information. The navigational system is based on an electromagnetic field generated at sufficiently high frequency preferably by intermediate reference stations. Preferably, the display is part of a flip-up/down visor stereographically showing a local map generated by an information storage device, and the display shows the location of the person on the map as well as the coordinates of that location on the map. The same system can be used by a person in a vehicle for navigational systems using lower carrier frequencies, the antenna and all communication and information storage and processing equipment being mounted on the vehicle and a wireless link being provided between the equipment mounted in the vehicle and the display apparatus mounted in the helmet or the equipment transmits directly to a vehicle mounted display.

Abstract: A radio position determation and message transfer system is implemented using a pair of satellites in geostationary orbit for replaying interrogation and replay signals between a ground station and a user-carried transceiver. The user portion is calculated based on the arrival times of replay signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points of the earth's surface. The stored terrain map allows accurate position fixed to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.

Abstract: A device for measuring the position (location and orientation), in the six degrees of freedom of receiving antennae (3) with respect to transmitting antennae (2) utilizing pulsed DC magnetic signals. The transmitting and receiving components consist of two or more transmitting antennae of known location and orientation with respect to each other. The transmitting antenna (2) are driven one at a time (or in the case of three or more antennae one or two at a time) by a pulsed, direct current signal. The receiving antennae (3) measure the transmitted direct current magnetic fields and the earth's magnetic field. A computer (5) is used to control the transmitting and receiving elements and to convert the received signals into location and orientation outputs.

Abstract: In a user's device of a GPS, the calculation of GDOP values for determining satellites to be used for the positioning is initiated periodically with a predetermined operation period. Once they are determined in a certain operation period, the processing for the positioning is repeatedly executed on the basis of signals from the determined satellites through the operation period, until satellites to be used are determined in a succeeding operation period. Plural times of the positioning can be executed for every time of the calculation of a GDOP value. If, therefore, a frequency of executing the positioning are made almost as equal as conventionally, a frequency of carrying out the time-consuming calculation of GDOP values is decreased, whereby the load of a microprocessor in the user's device can be remarkably reduced.

Abstract: The disclosure relates to methods and apparatus for separating radio signals arriving from different directions and for multiplexing signals intended for receivers dispersed in different directions. The methods and apparatus employ a plurality of antennas with spacing and individual feedline characteristics designed so that a modulation is imparted to each of a plurality of incident signals, for receiving antennas, and radiated signals for transmitting antennas, the modulation level of each signal being determined by the direction of propagation of the signal and by the spacing between antenna pairs. Accordingly, the orientation of lines connecting pairs of antennas as well as the spacing between antennas are set to inhibit the modulation in a particular direction, or to strip a particular modulation off a signal incident from a selected direction.

Abstract: In a global positioning system (GPS)/self-contained combination type navigation system for a vehicle, the GPS navigation data are received by the GPS antenna of the navigation system which are simultaneously transmitted from more than 3 pieces of satellites inclusively. From the GPS navigation data, GPS type velocity data is calculated, whereas self-contained type velocity data is calculated from self-contained type navigation data such as azimuth data and drive-distance data of the vehicle. Only when a difference between the self-contained type velocity data and the GPS type velocity data exceeds a threshold velocity, the GPS type velocity data is voided so as to determine the present position of the vehicle.

Abstract: A computer method is disclosed for accurately transforming multiple radar observations of aircraft into a common coordinate system for air traffic control applications. The method involves a transformation from radar observables of the target slant range, azimuth and altitude to the target position coordinates in a stereographic system plane for display. The method includes a conformal coordinate conversion process from geodetic to conformal spherical coordinates followed by a conformal stereographic projection process onto a system display plane. The resulting display of aircraft position on the system plane is more accurate than has been available in the prior art.

Abstract: A compass system and method incorporating a global positioning system (GP such as the NAVSTAR/GPS multi-satellite system, is configured to acquire accurate compass heading information without being affected by magnetic anomalies and without being dependent on the elapsed time since a previous position fix. The compass system comprises, inter alia, two antenna/preamplifiers located, for example, fore and aft a ship or aircraft separated by a predetermined distance d. A microprocessor/minicomputer portion of the system causes an electronic coaxial switch to switch a GPS receiver between the two antenna/preamplifiers automatically thereby measuring their absolute positions. The microprocessor/minicomputer computes and displays on a display unit a compass heading based on the knowledge of the absolute positions of the antenna/preamplifiers and the distance d therebetween.

Abstract: A position estimator for determining the position and velocity of a moving platform in cooperation with radio navigation aids is described incorporating an unbiased estimator, such as a least means square estimator, a biased estimator for determining the angle of inner section of the lines of position from the radio naviation aids for determining the liklihood of geometric dilution of precision (GDOP) and a switch for selecting the estimate of position and velocity from said biased estimator at first times and the unbiased estimator at second times. The invention overcomes the problem of accuracy degredation associated with a nearly collinear measurement geometry which causes the variance of the position estimates to be higly inflated.

Abstract: A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites being double-sideband modulated with their carriers suppressed. An antenna is positioned at each survey mark. The signals received by one antenna during a predetermined time span are separated into upper and lower sideband components. These separate components are filtered, converted to digital form, and then multiplied together. Their product is analyzed digitally by means of correlation with quadrature outputs of a local oscillator to determine the power, and the phase relative to that local oscillator, of the carrier wave that is implicit in the double-sideband signal being received from each satellite. Differences in Doppler shift are utilized to distinguish the carriers of different satellites.

Abstract: System and method are disclosed for determining position related data from spread spectrum signals using reconstructed carrier receivers with continuous wave interference rejection. The spread spectrum signals are collected at a mark with a substantially omni-directional antenna and continuous wave interference is then rejected at or near a selected frequency. The spread spectrum signals are then reconstructed to provide a continuous wave component at that frequency form which the position data may be derived. The data is derived without interference because the potentially interfering signals, if present, have been rejected before the components were reconstructed.

Abstract: A device for quantitatively measuring the relative position and orientation of two bodies in the presence of metals via measuring the position and orientation of receiving antennae with respect to transmitting antennae utilizing direct current electromagnetic field signals is hereby disclosed. The transmitting and receiving components of the instant device consist of two or more separate transmitting antennae of known position and orientation with respect to each other. Each transmitting antenna is driven one at a time by a pulsed, direct current signal. The receiving antennae measure the values of transmitted direct current magnetic fields one dimension at a time and those of the Earth's magnetic field as well, one dimension at a time.

Abstract: A method and apparatus is disclosed for accurately determining the spatial orientation of planar and linear features expressed along the exterior surface of a core sample. The core sample is positioned in a plurality of sequentially generated orthogonal electromagnetic fields. The core sample is retained by a device which allows complete rotation of the core sample about a predetermined axis while positioned in the electromagnetic fields. A stylus containing an antenna for detecting the electromagnetic fields is used to trace surficial features along the core exterior while simultaneously detecting components of the generated electromagnetic fields. The stylus provides an output to an analyzing device which calculates the coordinates of points along the core features. The coordinates are passed to a computer which has also been monitoring the rotation angle of the core.

Abstract: A method of rapidly reacquiring a pseudonoise spread spectrum coded signal after short outages includes calculating the new positions of the moving stations relative to the old positions of the moving stations and for determining the accurate displacement and the accurate direction the platforms have moved in their new direction after a short time outage. The method includes calculating a triangle which includes the displacement between the moving stations' old position and the moving stations new position and the included angle between the direction of movement and the line of sight between said moving platforms at the time of outage. A range displacement adjustment is calculated on the basis of the triangle for each moving station and the range factor resulting from this calculation is applied to the PN generators of the receiver and transmitter in each of the moving stations to independently adjust for each station's movement.

Abstract: The positions of a plurality of targets (26) are located using three or more sensors (20, 22, 24) such as radars which sense only the bearing angle of the targets. The intersecting bearing lines (30) form triangles (28) representing both true targets (26) and false targets (28). The false target triangles (28) are separated from the true target triangles by analyzing the size and position of each triangle. Bearing data defining the triangles is first ordered and then sequentially examined in a manner such that a first group of false targets (28) is eliminated from consideration. The bearing data defining the remaining triangles is processed through coarse and fine gates to eliminate second and third groups of false targets (28). A fourth group of false targets (28) is eliminated by using a global maximum likelihood procedure, in which a likelihood function is maximized through the use of discrete optimization techniques.

Abstract: An aircraft navigation system supporting a plurality of navigation modes. An error estimator for each navigation mode provides an estimated navmode error signal representative of an estimate of the error in the position signal generated by the associated navmode. A navigation mode selector enables the navmode having the smallest estimated navmode error signal that is consistent with procedure specified navaid criteria. The navmode computed position signal is processed through a low pass position filter. The estimated navmode error signal associated with the selected navmode is processed through a low pass position error filter having the same time constant as the low pass position filter to provide an estimated position error. The estimated position error is utilized in providing the INS and DEAD RECKONING navigation as well as to set a threshold for estimated navmode error signals sensor data validation.

Abstract: A system is provided for the centralized control of two groups of radiocommunications apparatus and two groups of radionavigational apparatus mounted on board an aircraft provided with two flight management computers, each of said flight management computers controlling the operation of the radionavigational apparatus of one of said groups. This system comprises two control devices dialoguing with each other respectively associated with said groups of radiocommunications apparatus and each including computing means, radiocommunications apparatus selection means, radionavigational apparatus selection means, frequency adjustment means and switching means. These two control devices are adapted for controlling the radiocommunications apparatus associated with the other, as well as the radionavigational apparatus associated with one of said flight management computers.

Abstract: An improved positioning system for a vehicle is shown. In the system, when radio wave can be received from only one satellite, the current position of the vehicle is computed based on a pair of navigational data, which are brought by radio wave received at the current time and by radio wave received at an earlier time.

Abstract: A method of localizing a moving body, by which the magnitude of parameters, which can give rise to bias errors, is estimated inversely from the difference between two locations of the moving body estimated by two different localization methods. Various quantities (position of sensors, propagation velocity of radiation, etc.), on the basis of which localization operations are carried out, can be corrected by using the magnitude thus estimated. The emission time of the radiation from the moving body can be estimated by the hyperbolic surface localization method and the spherical surface localization method can utilize the emission time thus estimated to localize the moving body. Further, localization errors caused by both localization methods can be estimated, so that it is possible to determine which localization method should be used to localize the moving body.

Abstract: A golfer wishing to know the distance to a specified feature on a golf course, operates a portable interrogation unit, to enter a request for the distance to the location of the feature. Transmitters located to define a triangle encompassing a substantial portion of the course transmit ranging signals, which are received by the portable interrogation unit. The portable interrogation unit includes a memory which stores the locations of the transmitters and the locations of predetermined features on the course and a CPU which processes the ranging signals received from the transmitters to determine the location of the portable interrogation unit and further to determine the distance from the portable unit to the specified feature. The portable interrogation unit then displays the determined distance. To survey the locations of the various predetermined features on the course, a portable survey unit is substituted for the portable interrogation unit.

Abstract: A golfer wishing to know the distance to a specified feature on a golf course, such as the pin on the next green, operates a portable interrogation unit, which transmits an interrogation signal including a request for the distance to the location of the specified feature. Three remote stations located to define a triangle encompassing a substantial portion of the course receive the interrogation signal and communicate interrogation information signals to a central station. The interrogation information signals include the interrogation signal data, remote station identification data, and pertaining to the location of the source of the interrogation signal relative to the remote station.

Abstract: An improved position measuring system for determining a vehicle's position by receiving radio waves emitted from satellites is shown. The system adopts successive approximation using a convergent computation, in which initially estimated values are computed.

Abstract: A method for passively locating in range and azimuth both active, such as radar, and passive objects. The present invention uses existing direction finding equipment located on a platform, such as an aircraft or ship. At the platform, the invention includes measuring the scan period of the radar, the time of intercept of the main beam of the radar, the angle of arrival of the radar main beam, the time of arrival of a bistatic signal echo from a passive object which has been illuminated by the radar, and the angle of arrival of the echo; calculating the difference between the angle of arrival of the echo and the angle of arrival of the radar main beam to obtain an angle .theta.; determining an angle .phi.