Abstract: A tilt predictor incorporated into a total station to predict the degree of tilt of the rotational alidade portion of a total station corresponding to the rotational orientation of the rotational alidade portion. In one embodiment, the present invention defines the plane of rotation for the rotational alidade portion with the rotational alidade portion disposed in a first rotational orientation. The rotational alidade portion is then rotated to the desired rotational orientation. This embodiment then predicts the degree of tilt of the rotational alidade portion at the desired rotational orientation.

Abstract: A method for correcting yaw in a DGPS (global positioning system) based guidance system mounted on a vehicle. The method corrects for a yaw induced heading/cross track error due to a DGPS antenna being mounted a significant distance from the point of operation (e.g., the vehicle operator's location, the center of the vehicle, etc.). The method determines a ground track of a vehicle using a DGPS system and a coupled antenna mounted on the vehicle. A heading of the vehicle is also determined using a compass mounted on the vehicle. The heading and the ground track are compared to determine whether a difference exits and the magnitude of the difference. Using the difference, the DGPS determined position is adjusted to be the position of the operator/center of the vehicle. Using this guidance information, an indication is generated operable for directing the vehicle to maintain a desired ground track.

Abstract: A system for determining the location of a moving signal-receiving station, when the primary location determination (LD) signals become unavailable because the antenna is adjacent to or within a signal-interfering structure, such as an urban canyon, a natural canyon, a forest or the like. Before the primary LD signals become unavailable, secondary LD signals are received at spaced apart locations and used to estimate the secondary LD signal source locations (preferably fixed). After the primary LD signals become unavailable, secondary LD signals, now with known source locations, are received and used, either alone or in combination with the remaining primary LD signals, if any, to determine the present location of the moving station. The primary LD signal sources can be GPS or GLONASS or LEO or other satellite-based sources. The secondary LD signal sources can be pseudolites or Loran signal towers or other ground-based sources.

Abstract: A receiver for tracking sources of position system signals transmitted as split spectrum signals is disclosed. The receiver provides a digital tracker to track a portion of the split spectrum signal. Each digital tracker may have an independent tracking loop solely for tracking a respective portion of the split spectrum signal. Such an arrangement provides anti-jamming benefits. Alternatively, the tracking loops may be dependent by providing information ascertained by one digital tracker to another digital tracker, thereby to provide an increased signal-to-noise ratio.

Abstract: Methods and systems for resolving the lock point ambiguity for the GPS receiver are disclosed. The method involves generation of the absolute lock point data bit by the reference station receiver, transmission of the absolute data bit to the rover receiver, and comparison between the raw lock point data with the absolute lock point data bit in the rover receiver. The system employs the reference station receiver, the rover receiver, and the communication link.

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: A system for restricting use of a vehicle by a selected vehicle operator to permitted time intervals and permitted vehicle travel corridors. If a driver is seated behind the driver's wheel, the system requires that the driver provide one or more samples of an ident indicium, such as a fingerprint, facial scan, retinal scan, voice sample or blood sample analysis, to identify the driver, or of a personal identification indicium contained on a token or card, or of personal information entered using a data entry device (e.g., keypad). When this indicium is satisfactorily presented and analyzed, the system allows operation of the vehicle (including selected vehicle accessories) but further determines (i) whether the present time and/or accumulated vehicle operation time and/or mileage is within a permitted time interval or accumulated time and/or mileage range and (ii) whether the vehicle present location and/or speed are within permitted ranges corresponding to the permitted time interval.

Abstract: Method and system for accurate vehicle navigation and tracking within a selected lane on a roadway or a waterway. A location determination (LD) receiver, carried on the vehicle, receives LD signals from satellite-based LD signal sources, receives LD signal correction information from one or more other wide area LD correction sources, estimates a corrected vehicle location (good to within 10-50 cm) and velocity (optional) relative to one or more lane boundaries that define the selected lane, and displays vehicle location and velocity within the lane. When the vehicle approaches a lane boundary too quickly, or is too close to the lane boundary, an alarm signal or other control mechanism can be activated. The LD correction information is delivered to the LD receiver via a channel of suitable bandwidth. The system can also be used to map and store lane boundary coordinates for selected segments of a roadway or waterway.

Abstract: A method and system for rapidly initializing a rover unit in a networked system. In one embodiment, the present invention acquires rover unit initialization data at a reference station. In one embodiment, the rover unit initialization data is selected from the group consisting of: ephemeris data, almanac data, satellite health data, ionospheric data, UTC and GPS time and approximate rover position information. In the present embodiment, the present invention then communicatively couples the reference station to a server station having memory for storing the rover unit initialization data. After communicatively coupling the reference station to the server station, the present embodiment transfers the rover unit initialization data from the reference station to the server station. The present embodiment then communicatively couples the rover unit to the server station. Next, the present embodiment supplies the rover unit initialization data from the server station to the rover unit.

Abstract: A system for restricting use of a vehicle by a selected vehicle operator to permitted time intervals and permitted vehicle travel corridors. If a driver is seated behind the driver's wheel, the system requires that the driver provide one or more samples of an ident indicium, such as a fingerprint, facial scan, retinal scan, voice sample or blood sample analysis, to identify the driver, or of a personal identification indicium contained on a token or card, or of personal information entered using a data entry device (e.g., keypad). When this indicium is satisfactorily presented and analyzed, the system allows operation of the vehicle (including selected vehicle accessories) but further determines (i) whether the present time and/or accumulated vehicle operation time and/or mileage is within a permitted time interval or accumulated time and/or mileage range and (ii) whether the vehicle present location and/or speed are within permitted ranges corresponding to the permitted time interval.

Abstract: A wireless seismic survey system is structured as a hierarchy of cell network layers, each higher level cell network layer covering a bigger area than a lower level cell network layer and receiving data from the lower level cell network layer. This hierarchical structure functions to concentrate collected data to a level that can be communicated to a central collection point, either through wireless, cable or other media. By defining cells to cover predetermined areas, transmission frequencies and/or transmission time slots or codes can be reused by cells sufficiently spaced apart to avoid co-channel interference, thereby increasing the amount of usable bandwidth.

Abstract: A GPS receiver having a fast time to first fix by comparing measured range rates for GPS satellites to GPS satellite velocities that are calculated from coarse GPS satellite orbital parameters. The coarse GPS satellite parameters are GPS almanac parameters or GPS ephemeris parameters that are older than the GPS-specified curve fit interval. The GPS receiver includes a satellite velocity calculator and a satellite line-of-sight calculator using the coarse GPS satellite orbital parameters previously stored in memory for calculating GPS satellite velocities and unit vectors to GPS satellites, respectively; a range rate measurer using GPS signal carrier measurements for determining range rates to GPS satellites; a user velocity calculator using the satellite velocities, unit vectors, and range rates for calculating a user velocity; and a user location integrator for integrating the user velocity from the last user location for a first location fix.

Abstract: The present invention is a method and apparatus for establishing a common datum georeferenced position of the phase centers of the antennas used by a system. The system includes a GPS receiver and an auxiliary transmitter. An auxiliary antenna of the auxiliary transmitter is co-located with a GPS antenna of the GPS receiver. The auxiliary antenna is at a known spatial relationship with the GPS antenna. An auxiliary position of the auxiliary antenna is determined based on the known spatial relationship.

Abstract: GPS position information is collected and stored in a computer system. The GPS position information includes time-stamps that indicates when the GPS position information was collected. The computer system uses the time stamps to generate an error correction file name for an error correction file that can be used to correct the GPS position information. Using the generated error correction file name, the computer system connects to a file server that stores differential GPS error correction files and copies the needed differential GPS error correction file. The computer system connects to the DGPS file server using the File Transfer Protocol of the global Internet.

Abstract: A DGPS system using GPS almanac data for determining the locations-in-space and the DGPS corrections for GPS satellites for providing a differentially corrected location of a remote GPS user receiver. A GPS reference receiver determines almanac-based DGPS corrections from the differences between ranges that are measured to GPS satellites and ranges that are calculated to the GPS almanac-based locations-in-space of the GPS satellites from the known location of the GPS reference receiver. The GPS user receiver measures pseudoranges to the GPS satellites. Then, in a first embodiment, the GPS reference receiver radios the DGPS corrections to the GPS user receiver. The GPS user receiver uses almanac-based locations-in-space for the GPS satellites and the almanac-based DGPS corrections for differentially correcting the measured user pseudoranges for providing a differentially corrected user location. In a second embodiment, the GPS user receiver radios the measured user pseudoranges to the GPS reference receiver.