Abstract: A method and apparatus are provided for performing remote control and viewing with a total station. The total station is operated remotely from a remote control and viewing unit (RCVU) by a single user. The total station has a measurement unit, a video camera aligned with the measurement unit for acquiring real-time images of a target, and a transceiver for transmitting video images to the RCVU and for receiving control data from the RCVU. The RCVU includes a transceiver for transmitting the control data to the total station and for receiving the video images from the total station. The RCVU also includes a display device for displaying real-time video images from the camera and includes controls for allowing the user to remotely align the total station with the target using the displayed video images. A fine-tuning focus control on the RCVU allows the user to remotely focus the camera.

Abstract: A surveying system for accurate determination of the position of a target based on ranging information provided by a positioning system is disclosed. A target is configured with a receiver to receive positioning signals from a positioning system, such as the Global Positioning System (GPS). The target transmits to a total station system position information estimating the target's location. The total station system, based on the location and orientation of the total station and the estimated location of the target, determines the angular displacement which is used to control a servo mechanism to align the total station unit with the target. Finer adjustments can thereafter be performed to more accurately align the total station to the target.

Abstract: An electronic distance meter comprises an integrated circuit from a GPS navigation receiver having a local pseudo-random number code generator for code demodulation that is connected to modulate either a polychromatic or a monochromatic light source. An optical system focuses the light on a distant target with an unknown range. Reflections from the distant target are focused on a light detector that produces a phase-delayed copy of the original pseudo-random number code. The time-of-flight to and back from the distant target is a function of the distance. The GPS receiver integrated circuit computes the range based on the code-phase delay to a precision better than one centimeter. The position of a remote target can be triangulated from several electronic distance meters each having known positions, e.g., determined by included GPS navigation receivers.

Abstract: A system for processing a PPS (precise positioning service) signal from a GPS (global positioning system) satellite to obtain PPS based positioning information therefrom. A first GPS receiver is adapted to process a PPS signal from a GPS satellite. The first GPS receiver is further adapted to output CVas (Crypto Variable Anti Spoofing) and SA correction information corresponding to the PPS signal. A second GPS receiver is adapted to receive the CVas and SA correction information from the first GPS receiver. The second GPS receiver is further adapted to process the PPS signal using the SA correction information received from the first GPS receiver and generate PPS based positioning information therefrom. The second GPS receiver does not include a KDP(key data processor). Accordingly, the second GPS receiver is not as tightly controlled as the first GPS receiver.

Abstract: Method and apparatus for using a plurality of correlators to improve the estimate of direct signal arrival time by identifying detailed features of a correlation function at and adjacent to the correlation peak. The errors in location of the center point of a correlation function R(.tau.), formed by the received signal and a stored copy of the expected signal, are assumed to be strongly correlated for narrow sample spacing and wide sample spacing of the correlation function. Alternatively, the multipath signal strengths and phases are estimated by a least mean squares analysis, using multiple sampling of a correlation function of an expected signal and an arriving composite signal that includes the direct signal and one or more multipath signals. Times of arrival or path delays of the direct signal and the multipath signals are determined separately. Path delays can be determined by at least three approaches: (1) identification of slope transition points in the correlation function R(.tau.

Abstract: The apparatus and method for estimation and minimization of the carrier multipath response envelope are disclosed. The reduction of the carrier multipath error signal is achieved by using the weighted or modified tracking or estimation circuits. The Modify and Weight signals are generated by the generator of Modify or Weight signals at five different circuit levels.

Abstract: A graphical machine-user interface includes a processor connected to a display screen to generate a screen display of individual items in groups together with the selector indication. The processor and a display screen are used to advantage to provide a rich keyboard function from a very limited set of pushbuttons. For example, five pushbuttons indicating "up", "right", "down", "left", and "middle" are recursively used to reduce a large two-dimensional matrix of item choices presented on the display to some subset, e.g., a top, right, bottom, left, or middle subset. If the reduction results in a choice of one, then that item is selected and output automatically. If the reduction results in a subset with more than one item, then a recursive process is used in which the selection process is repeated until the selected subset is reduced to a single item.

Abstract: A system and method for determining which of a plurality of travel paths is taken by vehicles through area in which the performance of an automatic vehicle location (AVL) system is reduced. In one embodiment, the present invention divides a geographic region into a plurality of signature zones which are further divided into a plurality of signature zone cells. The signature zone cells in each signature zone correspond to travel paths that pass through an area having structures that prevent reception of GPS signals or any area where GPS alone is not sufficient to discern travel path. The present automatic vehicle path determination system then calculates correlation values for positions in each signature zone cell that correspond to the travel paths that pass through the signature zone. The position of each vehicles is monitored by an automatic vehicle location (AVL) system.

Abstract: A data recorder and method for automatically displaying connections between feature icons as like features are recorded in the field. In setup, feature codes for identifying features of interest are entered and stored. In field operation, geographical features are recorded by entering the feature codes and either entering geographical locations for the features through a keypad or receiving the locations through an I/O interface from a location apparatus. A display shows the features as icons at points having geometrical relationships corresponding to the geographical relationships of features.

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: A jamming signal cancellation method and apparatus for removing an undesired in-band CW jamming signal from a desired spread spectrum signal. The jamming cancellation apparatus includes a limiter, a summer, and a feedback loop. The feedback loop includes the summer, a harmonic filter, a mixer, a loop/filter amplifier, and an adjustable gain control (AGC). The limiter limits the waveform of the input signal and issues a limited signal to the AGC and the mixer. The AGC controls the amplitude of the limited signal and passes a controlled amplitude signal to the summer. The summer takes a difference between the input signal and the controlled amplitude signal and passes a difference signal to the filter. The filter filters the harmonics that were created by the limiter and passes an output signal to the mixer. The mixer multiplies the filtered signal by the limited signal to provide an error signal that is proportional to the amplitude of the fundamental frequency in the difference signal.

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 navigation receiver which calculates the GPS satellites' positions by numerical integration. The GPS receiver of the present invention integrates over eccentric anomaly E as an independent variable rather than time, in order to use an integration method that is exact for sinusoidal motion, since the components of motion and time are sinusoidally related to the eccentric anomaly E. Using eccentric anomaly as an independent variable, the GPS receiver performs Leapfrog integration on a first sample and a second sample to determine a subsequent sample. The subsequent sample is uniformly spaced with respect to eccentric anomaly in comparison to the first sample and the second sample. The Leapfrog integration of the present invention is computationally efficient and exact over longer step sizes.

Abstract: A processor is connected to a display screen to generate a screen display of individual characters in groups together with the selector indication. Such characters typically belong in a language set, e.g., English, Japanese, Greek, etc. The processor receives from the numeric keypad a user selection of a number "1-9" that is associated with a particular one of the individual characters in a group highlighted by the selector indication. An index-and-fetch mechanism, typically implemented as a computer program sub-routine, provides for an indexed fetch of a digital data representation in a font memory of a character indexed according to the number "1-9". The fetched digital data is then available for more general use by a larger computer system, for example in the form of an "ASCII" output character.

Abstract: Method and apparatus for enhancing the accuracy of the elevation coordinate in a survey that uses GPS survey measurements to determine location coordinates for a plurality of survey locations. An optimal locally-best-fitting plane is combined with a geoid model that represents a local region of the Earth, in order to decrease the inaccuracy associated with an elevation coordinate in the survey to a fraction of a decimeter.

Abstract: An antenna aiming method and apparatus for automatically pointing an antenna to a selected distant location. The antenna aiming apparatus includes a database for storing data for distant locations, an electronic compass for determining a reference azimuth for the local antenna, and a global positioning system (GPS) receiver for determining a local location. A processor computes a pointing direction having an azimuth and an elevation from the local location to the distant location and then computes a horizontal rotation angle between the pointing direction and the reference azimuth and a vertical rotation angle from horizontal to the elevation. An antenna rotator servo-mechanism under processor control rotates the local antenna by the horizontal and vertical rotation angles for pointing the local antenna to the distant location.

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 one 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: A method for enhancing the accuracy of location coordinates and/or clock bias computed for a mobile user station that is part of a Satellite Positioning System (SATPS), such as GPS or GLONASS. A data processing station is provided with pseudorange corrections PRC(t;j;ref) for an SATPS reference station for each of M SATPS satellites (j=1, . . . , M; M.gtoreq.3) and with uncorrected location fix coordinates x'(t.sub.f), y'(t.sub.f)', z'(t.sub.f)' and/or b'(t.sub.f) for the mobile station for a selected location fix time t.sub.f. A matrix equation H(t.sub.f ;mob).DELTA.W(t.sub.f ;mob)=PRC(t.sub.f ;ref) relates a matrix .DELTA.W of location fix coordinate corrections for the mobile station to a matrix PRC(t;ref) of the pseudorange correction values, where H(t.sub.f ;mob) is an M.times.N matrix (M.ltoreq.N; N=3 or 4) with known entries computed from mobile station data. An inverse or pseudo-inverse matrix H(t.sub.f ;mob).sup.(-1) is formed satisfying the relation H(t.sub.f ;mob).sup.(-1) H(t.sub.

Abstract: The present invention provides a method and apparatus for expediently determining the azimuthal orientation of a total station. In one embodiment, the present invention is comprised of a total station having a vertical axis. The total station also includes a rotational alidade portion adapted to rotate about the vertical axis, and an electronic distance measuring portion. The present invention also includes a satellite-based position determining system antenna coupled to the total station. In the present invention, the satellite-based position determining system antenna is offset from the vertical axis. That is, in the present invention, the satellite-based position determining system antenna is not disposed coincident with the vertical axis of the total station.

Abstract: Disclosed herein is a low profile quadrifilar helix antenna system having the non-fed ends of the helix conductor arms shorted to a first ground plane, the ground plane mounted below the helix. The first ground plane is mounted perpendicularly to the central axis of the helix and extends radially outward therefrom to form an effective electromagnetic shield between the helix and adjacent ground planes. The extension of the first ground plane combined with the shorted non-fed ends of the helix arms minimize the influence of placement of the antenna system near adjacent ground conductors on the VSWR performance of the antenna. The conical frustum geometry of the helix conductors is configured to provide a low profile, resonant antenna. An integrated signal conditioning network is mounted within a cavity defined between the first ground plane and a second ground plane below the first ground plane.