Abstract: The method and the apparatus for the outputting in a uni-dimensional coordinate system the position coordinates and speed determined by the position and speed determining system (PSDS) are disclosed. The PSDS can include the SATPS receiver, the inertial positioning system, or the combination of both. The digital database of the geographic area is introduced by the user in the arbitrary coordinate system and is translated into the preferred coordinate system in order to define the uni-dimensional coordinate system. The large geographic area (LGA) and the small geographic area (SGA) embodiments are disclosed.

Abstract: The partial decoding algorithm for decoding the partially damaged differential satellite positioning system (SATPS) messages is disclosed. The algorithm is based on the modified parity test. The information included in the decoded messages can be used for the high level differential SATPS testing.

Abstract: Method and apparatus for improving the accuracy of a received composite signal s(t) that contains a known reference signal S.sub.d (t) with a known bit transition period .DELTA.tchip and that may contain a multipath signal S.sub.m (t;.chi.;b) with an unknown multipath time delay b and an unknown multipath gain factor .chi. (-1.ltoreq..chi..ltoreq.1). Autocorrelation functions AC(.tau.) and AC(.tau.;d) for the incoming signal and for the reference (direct) signal are determined, dependent upon a time shift variable .tau., and a double difference autocorrelation function .DELTA..DELTA.AC(.tau.)=AC(.tau.)-AC(.tau.-.tau.LE)-AC(.tau.;d)+AC(.tau.-. tau.LE;d) is formed, where .tau.LE is a selected time shift displacement satisfying 0 <.tau.LE.ltoreq..DELTA..tau..sub.chip. Two integrals or sums of .DELTA..DELTA.AC(.tau.) are measured over different selected time shift intervals. The ratio of these two integrals or sums provides a quadratic equation in the time delay variable b that is solved for b.

Abstract: A method for estimating the location of the source of a (possibly unfriendly) electromagnetic probe signal (threat radar) received by an aircraft as the aircraft moves along a chosen path. A signal direction finder on the aircraft determines geometric parameters describing a probe signal plane that contains a probe signal propagation direction, as received at the aircraft, at two or more selected times. A location determination system on the aircraft determines the location of the aircraft at each of the selected times. Information on the probe signal plane and the aircraft location is used to estimate initial location coordinates and, optionally, velocity coordinates and acceleration coordinates, for the probe signal source, in two dimensions or in three dimensions. Probe signal planes at additional selected times can be used to provide a check on, or provide a more reliable estimate for, the probe signal source location.

Abstract: A system and method for determining the minimum number of radiating elements required to achieve desired operating characteristics for a circular array of radiating elements. In one embodiment, the present invention determines the number of radiating elements required to space the radiating elements about the periphery of a circle such that a circular array of radiating elements is generated. The radiating elements are spaced apart from each other by a distance which is related to the wavelength of radiation at which the radiating elements operate. The present invention evaluates the maximum and minimum electric field strength generated by the circular array of radiating elements. By comparing the maximum field strength to the minimum field strength, the present invention measures the maximum ripple generated by the circular array of radiating elements. The maximum ripple generated by the circular array of radiating elements is then compared with a predetermined acceptable ripple level.

Abstract: A method and apparatus for providing navigation information including a simplified location display. The mobile unit includes a GPS position determination system including a GPS antenna, a GPS receiver, and a GPS processor. The system also includes a microprocessor and a database storage device. A map database is stored in the database storage device. In operation, the simplified location display system continually displays the travel path and location along the travel path that corresponds to the current location. The user may select optional displays which include the next cross street in the direction of travel, the last cross street in the direction of travel, the next parallel cross street to the right from the direction of travel, and the next parallel cross street to the left from the direction of travel.

Abstract: The output phase measures output by a digital phase lock loop (DPLL) are selectively modified to reduce instantaneous phase errors incurred whilst waiting until the DPLL locks before obtaining an accurate phase measurement of a signal. In one embodiment, the output phase of a low bandwidth DPLL is selectively modified when the input signal exhibits a significant dynamic transient by adding the error term generated by the DPLL phase detector to the output signal generated by the DPLL to generate a modified output signal used to perform phase measurements.

Abstract: A first form line is defined using two or more terrestrial locations. The first form line may be predefined or may be defined by user during a spraying operation. A second form line is then computed using positioning data obtained while following the first form line and a swathing offset corresponding to the width of a spray pattern. The second form line is updated according to one or more deviations from the computed path. The deviations may correspond to operator inputted corrections which allow for obstacle avoidance, etc. The updating generally occurs by following the second form line as defined by the positioning data and the swathing offset and then deviating from the second form line to accommodate one or more terrain features. New GPS data is collected during these steps of following and deviating from the second form line and new positions are computed from the new GPS data. Finally, the updated second form line is defined using the new positions computed from the new GPS data.

Abstract: Method and apparatus for determining non-iterative exact solutions for two, three or four location fix coordinates x, y, z and/or time offset b from pseudorange measurements from a plurality of location determination (LD) signals received at a GPS or GLONASS station. If M location fix coordinates are to be determined from N pseudorange measurements, the solution is exact if N=M. If N=M-1, the solution for two of the location fix coordinates lies at a point, on an ellipse or on an hyperbola. If N.gtoreq.M+1, a solution lies at the center of a sphere in M-dimensional space or in the interior of the sphere, according as N=M+1 or N.gtoreq.M+2.

Abstract: Apparatus for producing a self-authenticating visual image of a selected view, using a digital image forming means, such as a digital camera, together with a position determining system that provides position information, including location and/or angular orientation and/or time of observation at the time a digital image is formed and/or distance from the camera to a selected object. The digital image of the selected view is presented as an array of pixels with associated pixel values. The position information is incorporated in the digital image by altering selected pixel bit values for a selected authentication pattern P of pixels in a chosen subset CS of the pixel array; and this selected pattern may be determined using the position information. The position information may be encrypted, using an encryption key based on position information, and may be stored separate from, or as part of, the digital image.

Abstract: A system for selecting an optimal transformation T(G2;G1) between a first ellipsoid E1 (e.g., WGS 84) in a first global coordinate system G1, relative to which the survey measurements are made, and a second ellipsoid E2 (e.g., NAD 27) in a second global coordinate system G2. Location coordinates (x'.sub.m,2,y'.sub.m,2,z'.sub.m,2) for M previously-surveyed locations, numbered m=1, . . . , M (M>1) in the second system, and location coordinates (x'.sub.n,1,y'.sub.n,1,z'.sub.n,1) for N presently-surveyed locations, numbered n=1, . . . , N (M<N), in the first system are provided, where M presently-surveyed locations coincide with the M previously-surveyed locations. The transformation is chose.sub.n so that the images of previously-surveyed locations in the first system under the transformation T are as close as possible to the corresponding [previously-surveyed] locations in the second system. Give.sub.n an ellipsoid and a selected survey plane .tau.

Abstract: A system for monitoring location and speed of a vehicle, using a location determination system such as GPS, GLONASS or LORAN and an optional odometer or speedometer, for determining and recording the locations and times at which vehicle speed is less than a threshold speed for at least a threshold time (called a "vehicle arrest event"). Vehicle arrest event locations, times and time intervals are stored and/or printed to provide trip and mileage records and for efficiency monitoring. A vehicle odometer and/or speedometer can also be calibrated and/or corrected using this approach.

Abstract: A system for monitoring operation and location of a movable entity, such as a person, vehicle, movable equipment item or movable structure, at an activity site, such as a construction or mining site, that carries a location determination (LD) signal module to determine the entity's present location. When a restricted or hazardous activity occurs without warning (emergency) or is scheduled to occur at a selected location (fixed or moving) and selected time interval on the site, a buffer zone surrounding the restricted activity location is determined, and any movable entity that is within or will come within the buffer zone is advised to move or be moved elsewhere during the time the restricted activity occurs, unless the movable entity has an associated priority that is greater than an associated priority for the restricted activity. The buffer zone may vary with time in size, location and other characteristics.

Abstract: An antenna structure has a radiating element and a ground plane. The ground plane has a central region relatively closely spaced apart from the radiating element and a peripheral region extending away from the central region. The peripheral region comprises at least the conductive layer that extends radially beyond the radiating element and provides a sheet resistivity higher than that of the radiating element. Though physically small, the ground plane simulates an infinite ground plane, and the antenna structure reduces multipath signals caused by reflection from the earth.

Abstract: Method and apparatus for determining the location of a point on a rotating body, using location determination (LD) signals received from as few as one satellite, preferably non-geosynchronous. Where signals from two or more satellites are received, one may be geosynchronous. Pseudoranges are measured from one or more satellites at two or more selected, spaced apart observation times, and the simultaneous rotations of the body and the satellite(s) relative to each other result in different body-satellite constellations for which the initial location coordinates (and, optionally, signal receiver time offset) of the selected point are determined exactly, without approximation or iteration. The selected point may be motionless or may be allowed to move with known coordinate differences between the initial unknown location and the present location at each observation time. Pseudoranges from different satellites, or even from different satellite systems (GPS, GLONASS, LEO, etc.

Abstract: A handheld survey device includes a Global Positioning System (GPS) receiver for receiving position information, a pointer to point to the location to be measured, a measuring device to measure the distance between the handheld device and the location to be measured and a level and heading device to determine the level and heading of the handheld device. A processor located within the handheld device computes the position of the location using the position information, the distance measured between the handheld device and the location, and the level and heading information. The position computed meets the stringent accuracy requirements dictated by survey applications without the use of a range pole.

Abstract: A system for improving the accuracy of location coordinate determined in a survey of a chosen region, using a computer. A grid of spaced apart points is imposed on the region, and a set of survey control points is provided. A "near set" of nearest survey control points is associated with each grid point. For each grid point, a transformation T from a first (global) datum and coordinate system to a second (local) datum and coordinate system is determined that minimizes a collective difference between coordinates of each survey control point in the near set and the corresponding coordinates of that survey control point under the transformation T. For one, two or three coordinates of each grid point, a difference .DELTA. between the coordinate(s) of the grid point in the near set and the corresponding coordinate(s) of that grid point under the transformation T is computed. An interpolation function is determined that approximately matches the coordinate(s) difference .DELTA. at each grid point.

Abstract: A method for determining an improved position fix by performing postprocessing on a realtime differentially corrected GPS position. A remote rover unit containing a GPS receiver is used to determine a differentially corrected position according to measured pseudoranges and realtime pseudorange correction vectors is broadcast by a base station. The rover unit applies realtime corrections to measurements to determine a more accurate realtime differential position. It then stores the realtime differential position and the realtime pseudorange correction vector. Subsequently, postprocessing is performed to determine a postprocessed pseudorange correction vector. A difference vector representing the difference between the realtime pseudorange correction vector and the postprocessed pseudorange correction vector is then determined. This difference vector is applied to the realtime differential position to calculate a more accurate, improved position fix.

Abstract: Method and apparatus for providing security for a vehicle and for cargo transported on the vehicle. A location determination (LD) system determines vehicle location. A cargo unit carries a transceiver (or transmitter) that transmits a selected signal, either sua sponte or in response to receipt of a polling signal. The selected signal, if received by a receiver on the vehicle, is examined as to signal intensity, signal coding and/or time of receipt. If the received signal violates a selected condition, vehicle location is compared with an approved cargo destination. If the vehicle is not near a cargo destination, or if no selected signal is received at the receiver, an alarm signal is transmitted, which may include the vehicle location and/or the violated condition. If the LD system does not receive adequate LD signals to determine vehicle location, vehicle location coordinates are compared with a coordinate range for a signal obscuring region (SOR).

Abstract: A dual global positioning system (GPS) receiver navigation system. The system of the present invention includes a primary GPS receiver adapted to determine a first position. The primary GPS receiver is certified to a first integrity level and is further adapted to provide GPS navigation data to an external device. The system of the present invention also includes a secondary GPS receiver coupled to the primary GPS receiver. The secondary GPS receiver is certified to a second integrity level having less stringent requirements than the first integrity level. The secondary GPS receiver is adapted to determine a second position and monitor the primary GPS receiver to detect a fault condition by comparing the first position and the second position, such that the GPS navigation data is provided in accordance with the first certification level regardless of the second integrity level of the secondary GPS receiver.