Abstract: A centimeter level survey system includes reference base station and rover GPS units connected by a radio data link. Each includes recorders for the storage of raw measurement information including range, phase, cycle counts and time information. The rover unit is typically moved to points of interest during a survey while the base remains over a fixed, and known location. Generally, the base antenna is located to optimize a clear view of the sky. The rover is subject to interruption of the radio data link from the primary reference station. During periods that the rover is initialized and in contact with the primary reference station base station over the radio data link, the rover provides real time centimeter level position solutions to a survey user, otherwise, the rover records its raw measurements in a file that begins with the last valid initialization information and that ends with any newly reestablished initialization information.

Abstract: Determination of the verticality of various structures such as high rise buildings and towers is enabled through various methods involving use of a series of tiltmeter devices, a remote positioning system, or a combination of both. These methods are particularly useful in monitoring deviations from vertical during construction work and adjusting a jumpform. The tiltmeters are typically arranged in a line on the structure and polled to characterise varying tilt states in which displacement of each device increases with height up the structure. The remote positioning measurements are typically made in real time using a satellite based system such as GPS. Departures of a survey point on the jumpform from a vertical target line may be used to monitor verticality during the construction process.

Abstract: A GPS-based integrated controller module combines in a single integrated package or module a GPS receiver, a map, and a logic or decision module which provides an output control signal or control code. The map of the integrated module provides various representations. Continuous functions are provided with various types of coordinate systems, which can use interpolation between reference points in a grid system, or Taylor series representations. The integrated module performs discrete output functions such as providing a control code or a user's location either within or out of a particular closed area or polygonal zone, where each location shares a common characteristics with the other locations in the zone.

Abstract: A GPS antenna comprises an antenna body that can rotate between horizontal and vertical positions between the handle horns on the top of an optical total station. A GPS receiver embodiment comprises an integrated body and antenna that can similarly be rotated between horizontal and vertical positions between the handle horns on the top of an optical total station to avoid interference with the total station optics.

Abstract: Methods for determining integrity of pseudorange and pseudorange rate signals received from a plurality of M Satellite Positioning System satellites (including GPS and GLONASS), numbered j=j1, j2, . . . , jM, at a reference SATPS station (RS), using pseudorange or pseudorange rate signals received from the same satellites at a nearby signal integrity monitoring (SIM) station. Pseudorange correction values or, alternatively, pseudorange rate correction values, for SATPS signals received at an RS station and at the corresponding SIM station are computed, and difference values between the RS and SIM values are computed for each satellite. If the magnitude of each difference is less than a selected threshold difference, pseudorange corrections or pseudorange rate corrections for that reference station can be used by a nearby mobile station to differentially correct the mobile station location fix coordinates or velocity fix coordinates.

Abstract: A peripheral component interconnect (PCI) global positioning system (GPS) card for receiving a GPS signal. In a first embodiment the PCI card includes a GPS downconverter. In a second embodiment the PCI card including the GPS downconverter is integrated into a personal computer for correlating a GPS signal and computing a GPS location. In a third embodiment the PCI card includes a GPS downconverter and a GPS correlator. In a fourth embodiment the PCI card including the GPS downconverter and the GPS correlator is integrated into a personal computer for computing a GPS location.

Abstract: A GPS/radio antenna for receiving a GPS satellite signal and a DGPS radio signal. The GPS/radio antenna includes a GPS antenna using a microstrip antenna element for receiving the GPS signal having GPS location determination information, a radio antenna for receiving a DGPS radio signal in the FM broadcast frequency range having DGPS corrections, an enclosure, and a cable. The GPS/radio antenna may be included in a GPS/DGPS receiver system also including a receiver unit with an FM DGPS receiver for demodulating the DGPS radio signal and providing DGPS corrections, and a differential-ready GPS receiver for providing a differentially-corrected GPS location.

Abstract: A method and apparatus for determining an offset path from an actual path using a mobile surveying device. In one embodiment, a sequence of continuous measured points is generated using a satellite positioning system included with the disclosed mobile surveying device. Offset points are computed relative to the measured points using half angle calculations. Each offset point is computed relative to the middle point of three continuous measured points generated by the satellite positioning system along the actual path. The offset points are continuously generated with the mobile surveying device in real time and in the field.

Abstract: A flash memory using branded sectors for managing data files. The flash memory is divided into separately erasable blocks where each block may only be erased in its entirety. Each erasable block includes several file sectors, a sector allocation table (SAT) including an SAT record for each file sector, and a block information record (BIR) including status and an erasure count for the block. Each file sector may be designated as a file data sector, a file header sector, or block erasure sector. The data sectors include a data segment of one of the data files and is branded by a file identification and a sequence number. The brand and the size of the file sectors are used for locating the data sector for accessing the data segment.

Abstract: Methods for estimating the tracking error in estimated time of arrival of a composite incoming signal that contains a known, digital, spread spectrum signal S.sub.d (t) and that may contain one or more multipath signals whose source is the known signal. Some methods use linear, quadratic or other approximations for the measured correlation function AC(.tau.) for the early and late regions of the time shift variable .tau. (separated by a punctual value .tau.=t.sub.P). Other methods require only knowledge of the measured correlation function AC(.tau.) for one or two time shift values in the early region .tau.<t.sub.P.

Abstract: A method for determining J location fix coordinates, such as (x,y,z,b) for J=2-4, for a selected location, such as a mobile station location, with increased accuracy, for a satellite-based or ground-based location determination (LD) system such as GPS, GLONASS or LORAN. Pseudorange corrections for the pseudorange values measured at the reference station approximately at an observation time t' are used to correct the pseudorange values measured at the selected location. Location fix coordinates are computed from the pseudorange values at the selected location or at the reference station, using an exact, invertible transformation T(t') between the J location fix coordinates and J pseudorange values. Information including the location fix coordinates is transmitted from one station to another with a reduced or minimal number of information bytes and with small dynamic ranges.

Abstract: The transmitting and receiving apparatus and method for full code correlation operation under encryption for the Satellite Positioning System (SATPS) are disclosed. The apparatus includes a central station designed to receive SATPS satellites encoded information using a high gain antenna and a delayed correlation receiver. The central station extracts the encrypted satellite information and transmits it to the delayed correlation receiver. The delayed correlation receiver receives the encrypted satellite information using the standard SATPS antenna and performs the full correlation with the encrypted information received from the central station without requiring the secret encryption keys.

Abstract: A precision equivalent landing system. In one embodiment, a position determining system is coupled to an aircraft. The position determining system generates lateral position information of the aircraft with respect to a landing approach path. An altimeter is also coupled to the aircraft. The altimeter generates vertical position information of the aircraft with respect to the landing approach path. A graphic display disposed within the aircraft concurrently displays a visual representation of the lateral position of the aircraft with respect to the landing approach path and the vertical position of the aircraft with respect to the landing approach path. In so doing, the present invention provides both relative position and altitude of an incoming aircraft with respect to a landing approach path. Thus, the present invention provides a precision equivalent landing system without requiring the equipment and expense associated with ILS or FAA MLS precision landing systems.

Abstract: An antenna for broadcasting omnidirectionally is disclosed. The antenna includes a cylindrical housing which has a lip which includes slots adapted to receive a patch antenna strip and a conductive ring. A GPS receiver and electronics package may be placed in the center of the housing. The patch antenna strip which includes a number of patch antennas broadcasts and receives radio signals. The conductive ring absorbs energy broadcast from the patch antennas and rebroadcasts the signal omnidirectionally. The resulting signal has a high gain and a wide bandwidth. A third embodiment in which the conductive ring is incorporated into a housing cover is also disclosed. The antenna is easily and inexpensively assembled and is more durable and reliable than prior art antennas.

Abstract: A method and apparatus are disclosed for characterizing multipath-induced distortions in the autocorrelation function of a correlation receiver in order to reduce effects of these multipath-induced distortions on the accuracy of detecting the time of arrival of a received signal. The magnitude of the multipath-induced errors adversely affecting the shape of the autocorrelation function is estimated in real time, for example, through the use of secondary scanning correlators whose time base is independent of a typical receiver's detection-oriented correlators. This error is subtracted from the detection-oriented correlator's timing, thereby yielding a more accurate autocorrelation function.

Abstract: Methods for determining the present location coordinates of a user moving in a two-dimensional or three-dimensional space, with reference to an old map that may be inaccurate. Location coordinates of two or three non-collinear landmarks in two dimensions, or coordinates of three or four non-coplanar landmarks in three-dimensions, are indicated on the old map. Corresponding location coordinates are also estimated using a location determination (LD) system, such as GPS, GLONASS, Loran, Tacan, Decca, Omega, VOR, DME, JTIDS, PLRS or an FM subcarrier system. Location coordinates for two or more physical landmarks can be used to determine coordinates for a landmark representative. The user's location coordinates are also determined or provided using the LD system. A distance or separation vector from the user location to landmark number i (i=1, . . . , N; N=2,3) is computed in the LD system.

Abstract: A method and an apparatus using a low Earth orbiting (LEO) satellite signal to augment the Global Positioning System (GPS) for finding a location vector between a GPS user receiver and a GPS reference receiver. The GPS user receiver computes a LEO user-reference carrier phase difference and a GPS user-reference carrier phase difference for the LEO satellite signal and a GPS satellite signal, respectively, received simultaneously at the GPS user receiver and the GPS reference receiver. Carrier phase double differences are computed from a difference between the GPS user-reference carrier phases from two GPS satellites and either the LEO user-reference carrier phases from two LEO satellites or the GPS user-reference carrier phase from one GPS satellite and the LEO user-reference carrier phase from one LEO satellite. The location vector is computed from a difference between the double differences for two satellite geometries.

Abstract: A system and method for determining which of a plurality of vehicles is able to respond most quickly to an event. In one embodiment, the present invention divides a geographic region into a plurality of geographic cells. The present automatic vehicle recommendation system then calculates a response time for each of the plurality of vehicles to travel from each of the geographic cells to every other of the geographic cells. The position of each of the plurality of vehicles is monitored by an automatic vehicle location (AVL) system. The present automatic vehicle recommendation system then determines which of the plurality of vehicles is able to respond most quickly to an event reported to a computer aided dispatch (CAD) system. The event is located within one of the geographic cells. The present invention then communicates to the CAD system which of the plurality of vehicles is able to respond most quickly to the reported event.

Abstract: In a GPS navigation satellite receiver, a pseudorange step detection method integrates the pseudorange rates to predict expected changes in the pseudoranges from one measurement to the next. The pseudorange rate is directly measured as the carrier Doppler shift. The pseudorange and pseudorange rate from a last measurement from each satellite and a pseudorange rate from a new measurement are used to estimate the expected pseudorange. Such estimate accounts for vehicle velocity and accelerations. The expected pseudorange is compared to a newly measured pseudorange. An impermissible pseudorange step is declared when the difference exceeds a variable threshold. Tests can be done on measurements taken up to ten seconds apart, e.g., using a threshold of five hundred meters. The maximum position dilution of precision is typically set at a value of twelve. Satellites that manifest a pseudorange step are thereafter excluded from participating in subsequent position solution activity.

Abstract: Apparatus that is carried on a land vehicle, a marine vehicle or vessel, or an airborne vehicle or vessel for notifying others that a vehicle accident or other abnormal situation has occurred and for notifying others of the location of the vehicle at the time of the accident. The vehicle carries an distance measuring system (DMS) signal antenna and receiver/processor that receives DMS-type signals from one or more DMS signal broadcasters and determines the present position of the vehicle, plus an activatable transmitter. The vehicle also carries an abnormality sensing means that senses the occurrence of an accident or other abnormal situation involving the vehicle or a vehicle occupant. When an abnormal situation is sensed, the abnormality sensing means automatically activates the transmitter, which then communicates the fact that an abnormal situation has occurred and the location of the vehicle at the time the event occurred.