Abstract: The method of supplementing the satellite data by the satellite-calibrated baro data when the receiver autonomous integrity monitoring function (RAIM) is unavailable and when the horizontal protection level (HPL) does not satisfy the horizontal alert limit (HAL) requirement is disclosed. The baro data is calibrated with satellite data if maximum weighted vertical dilution of precision with one satellite removed at one time (max {SubWVDOP}) is less than a predetermined threshold (TSUB) and if a test statistic is less than a predetermined test statistic threshold (TST). The HPL is re-computed using the satellite-calibrated baro data. The re-computed HPL could satisfy the HAL requirement which would make the RAIM function available when it would be otherwise unavailable.

Abstract: A method and apparatus which overrides a guidance control system so as to disengage the automatic steering control feature when an emergency condition is determined to exist. A sensor is coupled to the steering system which detects movement of the steering wheel. When movement of the steering wheel is sufficiently abrupt, the logic of the override system generates an override signal. The override signal is communicated to the guidance control system so as to return control of the vehicle to the user. The sensor is connected to either the steering wheel itself or to the hydraulic system. When the vehicle includes an electro-hydraulic system, the logic system may be directly connected to the electrical circuits of the electro-hydraulic system. Multiple sensors may be used for activation of the override. In one embodiment a sensor is coupled to the braking system for sensing depression of the brake pedal. In another embodiment, a sensor is coupled to the clutch system for sensing depression of the clutch petal.

Abstract: An improved time transfer mechanism and method are disclosed. In one embodiment, the present invention provides a computer implemented method for transferring time, includes generating a first time stamp at a processor; triggering a time transfer event; generating a second time stamp at the processor; and receiving a reference time stamp at the processor. Triggering the time transfer event can further include sending a request for a time stamp signal to a device that is dedicated to time synchronization. The present invention also includes specific hardware for performing the time transfer method.

Abstract: A method and a system for remote control of a rover over a long base line is disclosed. The system includes a primary base station (PBS), a secondary base station (SBS), a rover, a primary long line data link between PBS and SBS, and a secondary two-way data link between the SBS and the rover. The primary data link and the secondary data link comprise a long baseline feedback loop that is used to transmit the control data to the rover, to adjust the control data, and to transmit back from the rover to the SBS and to the PBS the collected feedback data.

Abstract: A three dimensional laser tracking and control system is disclosed. The system includes a laser beacon generating a three dimensional rotating and scanning laser beam that covers a three-dimensional area. Each mobile unit has identification number (ID) and is equipped with a intelligent reflector (IR). Each mobile unit uses its intelligent reflector (IR) to communicate to the signal system its ID and the time of illumination by the laser beam. The signal system calculates the three dimensional coordinates for each mobile unit and communicates the positional data back to each mobile unit using the same laser beam during the subsequent rotation cycles.

Abstract: A pseudolite for transmitting a global positioning system (GPS) signal having identification information for a GPS satellite that is currently out-of-view. The pseudolite mimics a global positioning system (GPS) signal by using a C/A pseudorandom (PRN) identification code for a GPS satellite that is allocated in the GPS system but is unreceivable in the local vicinity and location-determination information including ephemeris data corresponding to the geographical location of the pseudolite. In order to ensure that two of the GPS pseudolites in the same vicinity do not use the identification PRN code from the same out-of-view GPS satellite, the pseudolite listens first before transmitting to detect the identifications in the received GPS signals.

Abstract: A system for tracking the location of, and for providing cellular telephone handoff for, a mobile cellphone user as the cellphone user moves from one cellzone to another. A boundary curve B12 between a first cellzone and an adjacent second cellzone is defined in an electronic map by an equation hB12(x,y,z)−K12=0 for points with spatial location coordinates (x,y,z) lying on the curve B12, where K12 is a selected constant. First and second quasi-boundary curves QB1 and QB2, lying within the first and second cellzones, respectively, are defined, where each point on the curve QBi (i=1,2) lies at a selected distance di from the boundary curve B12. A region CR12 of points lying between the quasi-boundary curves QB1 and QB2 and including the boundary curve B12 is defined. The present location of the cellphone user is determined using a Satellite Positioning System (SATPS) such as GPS or GLONASS.

Abstract: Real time kinematic (RTK) global positioning system (GPS) technology is integrated with precision farming methodologies to provide highly accurate seeding, cultivating, planting and/or harvesting operations. RTK GPS systems are used to control fully or semi-autonomous vehicles in these operations and may allow for precision planting of seeds (e.g., from a seeder equipped with an RTK GPS receiver and related equipment) and/or precision weed removal (e.g., using a vehicle fitted with weed eradication mechanisms such as augers and/or herbicide sprayers). Crop specific fertilizer/pesticide application is also enabled through the use of centimeter-level accurate positioning techniques.

Abstract: A GPS navigation receiver channel tracks satellites' Doppler frequencies sequentially during the twenty milliseconds that the signal is coherent in each bit time of the navigation data modulation. It measures frequency by differencing the angles of signal-vector sums weighted by parabolic humps, exploiting the commutativity of linear processing operations to raise the signal-to-noise ratio before the nonlinear operation phase of detection.

Abstract: A method and apparatus for accurately positioning a tool on a mobile machine are provided. The machine operates within a work area about which one or more stationary laser-based subsystems are positioned. The machine includes an on-board subsystem, which comprises a processor, a satellite positioning system (SPS) receiver, a stored digital terrain model (DTM), and a photosensor for detecting a laser beam. The laser beam provides a reference level that is used to adjust the position of the tool. The on-board subsystem determines the current position of the machine using the SPS receiver and accesses the DTM to determine a design elevation corresponding to the current location of the machine. Based on the design elevation, the on-board subsystem computes a height command and transmits the height command to at least one of the laser-based subsystems.

Abstract: A global positioning system (GPS) receiver having a fast time to first fix using the velocity of a GPS satellite and an approximate time. The GPS receiver includes a GPS antenna for receiving a GPS signal, radio frequency circuitry for downconverting and sampling the GPS signal, a reference timer for providing a reference clocking signal, a digital signal processor for receiving the sampled GPS signal, and a microprocessor for executing program codes in a memory. The digital signal processor cooperates with the microprocessor for correlating the sampled GPS signal to an internal GPS replica signal based upon the reference clocking signal. The memory includes program codes for a pseudorange detector for measuring code phase offsets, a directional cosine calculator for calculating unit vectors, a satellite velocity calculator for calculating vector velocities, a pseudorange linearizer for determining linearized pseudoranges, and a velocity-enhanced location calculator.

Abstract: Apparatus and method for a location determination and reporting (LDR) system for clandestinely or surreptitiously determining and reporting a missing vehicle present location. The vehicle may be stationary or moving and may be anywhere within reach of a cellular central station to which the location is reported. The vehicle is equipped with a location determination (LD) unit (preferably hidden on the vehicle) that receives LD signals and determines the LD unit present location, a specially configured cellular telephone, and a call interceptor. When the vehicle is reported missing, a central station or the vehicle operator interrogates the vehicle LDR system by transmitting a location interrogation signal, commanding the LD unit to transmit its present location. The vehicle phone does not signal receipt of an incoming call for an initial time period of selected length &Dgr;td, awaiting possible receipt of a location interrogation signal.

Abstract: A distance interpolator incorporated into a total station and a method for digitally interpolating a distance measurement from the total station to a target, such that the distance interpolator measures the distance from the total station to the target using primarily digital electronics and statistical analysis. In one embodiment, the total station transmits an energy pulse from the electronic distance measuring portion of the total station, with the energy pulse directed at the target. This embodiment then receives at the electronic distance measuring portion the energy pulse reflected from the target. This embodiment also contains a reference oscillator and digital counter, which counts the number of reference oscillator clock pulses that elapse from the time the energy pulse is transmitted to the time the reflection of the energy pulse is received.

Abstract: Method and apparatus for monitoring the present location of a person (“confinee”) who is to be confined to a designated site, which site can have a diameter as small as a few meters or as large as several kilometers. The present location of the confinee is checked at selected time intervals with time periods ranging from one second to thousands of seconds, as desired. The confinee wears a location-determining (“LD”) unit that receives electromagnetic signals that contain information allowing determination of the present location of the LD unit, and thus of the confinee, from three or more non-collinear outdoor LD signal sources and from three or more non-collinear indoor LD signal sources. The indoor LD signal sources may be radiowave transmitters. The outdoor LD signal sources may be transmitters for a Loran, Omega, Decca, Tacan, JTIDS Relnav or PLRS or similar ground-based system, or transmitters for a satellite positioning system, such as OPS or GLONASS.

Abstract: This invention provides apparatus and methods for obtaining information for aligning a reference signal with a received signal for global positioning satellite receivers which employs at least one correlator for correlating the received signal with the reference signal to generate an accumulated result; the correlator having a comparator to compare the received signal with the reference signal and an accumulator which is either selectively enabled/disabled to prevent overflow errors or is read periodically before an overflow occurs.

Abstract: A method and apparatus for providing navigation and information services. A mobile unit which includes a microphone and a speaker is used to communicate between a user and a service location. The service location includes a computer and data storage which includes data on geography, roads, road conditions, traffic and other data which may be of use to a user. The mobile unit includes a receiver and position determination processing circuitry for location determination. A user may obtain navigation information and routing information by pressing a button on the mobile unit so as to initiate communication with the service location. The user then verbally requests the information which he needs by speaking into the microphone. Using location data which is transmitted to the service location and the data in data storage, the computer compiles a response which is transmitted to the mobile unit and through the speaker for communication to the user.

Abstract: Apparatus and method for a location determination and reporting (LDR) system for clandestinely determining and reporting a missing vehicle present location. The vehicle is equipped with a handheld cellular phone unit and controller that are accepted and held by a cellular phone cradle that can include electrical poster and/or a location determination (LD) unit to determines the LD unit present location. The cellular phone unit can operate on one cellular channel or on two distinct cellular channels. When the vehicle is reported missing, the central station interrogates the vehicle LDR system to determine the vehicle present location. A location interrogation signal is transmitted, commanding the LD unit to transmit its present location. The cellular phone does not signal receipt of an incoming call for an initial time period of selected length .DELTA.td, awaiting possible receipt of a location interrogation signal on the first cellular channel.

Abstract: Method and apparatus for estimating a line bias for a signal received from a common signal source at each of two or more GPS signal receivers. Single difference solutions are obtained for angular orientation of an antenna array and for antenna location, using a two-thread or two-procedure process for determining and updating line bias variation within each of a sequence of time intervals.

Abstract: A combined satellite positioning and electro-optical total station system including a satellite navigation receiver and a reference oscillator with a reference frequency output that can be related to precision time standards obtained from orbiting navigation-satellite transmissions. Such time standards are output by the satellite navigation receiver and are highly precise. An electronic distance meter (EDM) is included and has an EDM-transmitter for launching an out-bound signal to a distant target, and an EDM-receiver for receiving a reflected signal from the distant target. A phase measurement device is connected to the reference oscillator, and also to both the EDM-transmitter and EDM-receiver. It provides for a measurement of the difference in the number of cycles of the reference frequency between the out-bound signal and the reflected signal.

Abstract: The present invention provides a radio navigation emulating GPS device. In one embodiment, the radio navigation emulating GPS device receives an identifier associated with a conventional radio navaid. The present radio navigation emulating GPS device then retrieves latitude and longitude information corresponding to the received conventional radio navaid from a database. A satellite based position information system generates position information for the aircraft on which the present radio navigation emulating GPS device is disposed. The present radio navigation emulating GPS device then generates navigation information for the aircraft using the retrieved latitude and longitude information and the satellite based position information for the aircraft. The present radio navigation emulating GPS device then presents the navigation information in a manner which emulates the presentation of navigation information generated by a conventional radio navigation device.