Abstract: A position-related multi-media presentation system for a vehicle. A position determining system generates position information of a vehicle. The position information is transferred to a multi-media system. The multi-media system presents information related to the position of the vehicle to an occupant of the vehicle. In one embodiment, video information is displayed on a display unit located on the back of a seat of an aircraft. The video information provides views related to features over which the aircraft is flying.

Abstract: A real-time kinematic system includes base and rover GPS units connected by a data link. The rover unit is typically moved to points of interest during a survey while the base remains over a fixed, and known location. An initialization testing program of the present invention is mounted on a personal computer platform that forces in the rover a loss of signal tracking, thus simulating losses in signal reception caused by obstructions of the satellite signals. A complete initialization is forced to occur. The test program uninitializes the RTK solution by causing a loss of integer ambiguities resolution by forcing a loss of lock on one or more satellites. The test program then monitors the subsequent initialization process, e.g.

Abstract: The system for the remote computer assisted precise pile driving and rig drilling operations is disclosed. The system includes a base station, a computer assisted precise pile driving and rig drilling (CAPPDARD) system, and a communication link. The CAPPDARD system includes a moving platform including a piling rig and a mast, a location determination means, a computer, and a communication means. The CAPPDARD system can be operated manually or remotely from the base station.

Abstract: A dual frequency vertical antenna for radiating a first and a second airwave signal in response to a first and a second conducted signal, the first airwave signal having a first frequency and the second airwave signal having a second frequency lower than one-half the first frequency. The antenna includes a horizontal base member and a vertical mast, including a coaxially disposed rod, projecting upward from the base member to a masthead. For feeding the conducted signals, a lower mast extension projecting downward from the base member and a tuning sleeve projecting either upward or downward from the base member are tuned to 1/4 wavelength at the first frequency and a single coaxial cable is connected between the base member and a feedpoint on the rod. The first airwave signal radiates from a dipole formed of an 1/4 wavelength upper rod extension extending upward from the masthead and a concentric 1/4 wavelength upper sleeve external to the mast projecting downward from the masthead.

Abstract: A system embodiment of the present invention comprises a fixed and a roving pair of four-observable GPS receivers and a communication link between them for double differencing code and carrier measurements. Carrier phase integer ambiguities are resolved efficiently by searching the simultaneous narrow-lane intersections of both the L1 and L2 wave fronts propagated by the GPS satellites being tracked. External constraint information, such as elevation, is additionally used to speed up integer ambiguity resolution. Data between the reference station and the rover is communicated in compressed form at a regular interval, e.g., once a second at each epoch, and demi-measurements of carrier phase are obtained more frequently, e.g., ten times a second, and used to propagate solutions between epochs.

Abstract: The channels of a GPS receiver system are dynamically allocated during acquisition mode to hierarchically chain a slave channel module to a master channel. Each channel circuit includes two correlators, where each correlator receives a digitized received GPS signal and a delayed local PRN reference code signal to provide an output signal to an accumulator. During acquisition, the system provides two correlator channels where each channel includes two correlators for a total of four correllators. A PRN reference code signal is progressively delayed to provide a sequence of progressively delayed PRN reference code signals, where one of the sequence of progressively delayed PRN reference code signals are applied to each of the correlators. Each correlator channel also includes a digital mixer which receives a digitized GPS IF signal and a digital carrier reference signal and which provides the digitized received GPS signal.

Abstract: A combination of a GPS receiver for determining a user's position in terms of latitude and longitude, a database that indexes approximately 53,000 USGS 7.5 minute series topographical quadrangle maps by the latitude and longitude of at least one point on each map, and an interpreter and display that communicates the particular USGS map that represents the user's position together with the ruler dimensions left/right/up/down from a reference point on that map which pinpoints the user's position on the map. The database is stored in the permanent memory of the GPS receiver and the interpreter and display are controller by a microcomputer included in the GPS receiver. The reference points include sixteen intersections on the map of 2.5 minute intervals of latitude and longitude contained in each 7.5 minute series quadrangle.

Abstract: A GPS receiver having a rapid acquisition of a GPS satellite signal when a normal operational mode is entered after a low power standby mode. The GPS receiver includes an RF section for receiving the GPS satellite signal and providing an GPS IF signal, a correlator section for providing a correlation signal for the correlation between the GPS IF signal and a GPS replica signal, and a microprocessor section for receiving the correlation signal and calculating a geographical location of the GPS receiver. The GPS replica signal is based upon a reference frequency from a reference oscillator and a reference time from a timer. In the standby mode, the operation of the RF section, correlator section, and microprocessor section is inhibited while the reference oscillator and time continue to operate.

Abstract: A GPS receiver having a normal mode to receive GPS satellite signals and to provide location information, and a low power standby mode. A microprocessor system in the GPS receiver causes the GPS receiver to alternate between the normal mode and the low power standby mode in order to reduce the average power consumption in the GPS receiver. In the normal mode a GPS antenna receives GPS satellite signals, the GPS frequency downconverter converts the frequency of the GPS satellite signals to an intermediate frequency, a digital signal processing system processes the intermediate frequency to provide GPS satellite signal correlation information. The microprocessor system processes the correlation information and provides location information to a user. In the standby mode, the operating power is inhibited in the GPS antenna and the GPS frequency downconverter, the system clock is inhibited in the digital processing system, and the microprocessor clock is inhibited in the microprocessor system.

Abstract: A GPS receiver system to determine and display a geographical differential Global Positioning System (DGPS) location where the components of the system are interconnected with an airwave infrared (IR) link. The system includes a GPS Smart Antenna receiver module to determine the geographical location of the module, a DGPS radio receiver to receive an airwave radio frequency DGPS signal having DGPS correction information, and a personal computing display to run an application program and to display the geographical DGPS location and application information that is useful to a user. The GPS Smart Antenna receiver module and the DGPS radio receiver are switched on and off from the personal computing display through the airwave IR link.

Abstract: A method, implementable on a computer, for filtering time-varying location solution coordinates P.sub.x,n, P.sub.y,n, and P.sub.z,n, determined by a Satellite Positioning System (SATPS, usually GPS or GLONASS), which operates in a static mode and a dynamic mode, to reduce large discontinuities and control the rate at which a changing sequence of measurement errors can induce a change in a sequence of location solutions. As an initial step, SATPS location solutions P.sub.x,n, P.sub.y,n, and P.sub.z,n, and SATPS velocity solutions V.sub.x,n, V.sub.y,n, and V.sub.z,n are generated for selected fix times t=t.sub.n with essentially no time lag in these solutions, when recent measurements are available from all satellites in the solution constellation. Sequences of filtered location coordinates {P.sup..LAMBDA..sub.x,n }, {P.sup..LAMBDA..sub.y,n }, and {P.sup..LAMBDA..sub.

Abstract: A method for compensating for temporary loss of differential GPS correction signals for a satellite, numbered j, during an IODE changeover interval. Differences .DELTA.e.sub.i (t;j;n+1,n)=e.sub.i (t;j;n+1)-e.sub.i (t;j;n) (i=1, . . . , I) are formed for I ephemeris parameters used to describe the ephemeris for the satellite (j) during IODE intervals number n+1 and n. These differences are approximated for a DGPS blank-out time interval, given by t(j;n+1).sub.IODE .DELTA.t.sub.rev,mob .ltoreq.t<t(j;n+1).sub.IODE +.DELTA.t.sub.ch +.DELTA.t.sub.rev,ref, during which a GPS reference station continues to broadcast DGPS correction information based on the old ephemeris data that was valid during the preceding IODE time interval, given by t(j;n).sub.IODE .ltoreq.t<t(j;n+1).sub.IODE. These ephemeris differences are used by a mobile station that receives DGPS correction information from the GPS reference station to produce corrected GPS information for a blank-out time interval.

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 (xi',yi') of two or three non-collinear landmarks in two dimensions), or coordinates (xi',yi',zi') of three or four non-coplanar landmarks (in three-dimensions), are indicated on the old map. Corresponding location coordinates (xi,yi) or (xi,yi,zi) are also determined or made available using a location determination system (LDS), such as GPS, GLONASS, Loran, Tacan, Decca, Omega, VOR, DME, JTIDS, PLRS or an FM subcarder system. Location coordinates (xi,yi) (or (xi,yi,zi)) for two or more physical landmarks can be combined into coordinates for a landmark representative. The user's location coordinates (xu,yu) (or (xu,yu,zu)) are also determined or provided using the LDS.

Abstract: Methods for secure communication of location and other information by two spaced apart receivers in a location determination (LD) system, such as GPS, GLONASS and LORAN-C, that use pseudorange corrections to enhance the accuracy of the computed present location of an LD receiver. A pseudorange correction signal PRC(t;i;j), presenting a correction of a pseudorange measurement made at time t at an LD receiver number i from an LD signal issued by an LD signal source number j, is transmitted at a consecutive sequence of times t=t.sub.0, t.sub.1, t.sub.2, . . . , t.sub.n. The pseudorange correction signal PRC(t.sub.n ;i;j), or a message sent in a time interval t.sub.n-1 <t.ltoreq.t.sub.n, is encrypted, using an encryption key that is a function of and depends non-trivially upon one or more of the preceding pseudorange correction values PRC(t.sub.k ;i;j) (k.ltoreq.n-1). This encryption key varies from one time interval t.sub.n-1 <t.ltoreq.t.sub.

Abstract: Apparatus and method for accurately determining the location of an target or other designated object by an observer that is spaced apart from the object. The observer views the target through a viewer and rangefinder and determines the distance of the target from the observer. The observer determines its own location coordinates, and the angular orientation of the rangefinder relative to a selected line or plane, using Satellite Positioning System (SATPS) signals (such as GPS or GLONASS signals) received by three SATPS antennas and processed by a common SATPS receiver/processor. The SATPS receiver/processor then determines the displacement or offset coordinates of the target relative to the observer and displays the target coordinates on the target image seen in the viewer. The target location coordinates and/or the visual image of the target seen in the viewfinder are transmitted to a control station for subsequent use.

Abstract: An antenna system comprises a stack of elements that include a GPS patch antenna on a groundplane with an associated low-noise amplifier (LNA), a first Faraday shield of flat ribbon cable covering a first ferrite rod magnetic field antenna, a second ferrite rod magnetic field antenna separated from and orthogonal to the first ferrite rod magnetic field antenna, a second Faraday shield of flat ribbon cable covering the second ferrite rod magnetic field antenna and having a LNA for each of the ferrite rod magnetic field antennas. A third Faraday shield is positioned between the first and second ferrite rod magnetic field antennas. All the Faraday shields are connected to ground such that there are no loops that may act as shorted turns to avoid desensitizing the ferrite rod magnetic field antennas.

Abstract: Method and apparatus for monitoring present location of a site arrestee confined to a permitted site of arbitrary size. Present location of the arrestee can be checked at selected time intervals of several hundred milliseconds to thousands of seconds, as desired. The arrestee wears a location-determining ("LD") unit that receives electromagnetic signals that contain information allowing determination of the present location of the LD unit and arrestee, from three or more non-collinear signal sources. These sources may be radiowave subcarrier transmitters, or may be a combination of radiowave subcarrier transmitters and (1) transmitters for a Loran, Omega, Decca, Tacan, JTIDS Relnav or PLRS or similar ground-based system, or (2) transmitters for a satellite-based positioning system, such as GPS or GLONASS. Present location or change in present location of the LD unit is determined and compared with the permitted site boundary at selected times to determine if the arrestee is present at the site.

Abstract: Method and apparatus for reducing the contributions of receiver noise signal error and multipath signal error from signals received in a Satellite Positioning System (SATPS) from one or more SATPS satellites by formation and appropriate filtering of differences of signals DD that are differences of SATPS signals received by the SATPS receiver/processor. A difference signal DD of code-phase-derived delta range signals and carrier-phase-derived delta range signals is formed, and this difference signal is passed through a first statistical processing filter with an associated time constant .tau.1 in the approximate range 50-[500] 100 sec, to produce smoothed or filtered signal with the estimated receiver noise error reduced or removed. The difference signal DD is passed through second and third statistical processing filters having associated time constants .tau.2=5-20 sec and .tau.

Abstract: A GPS receiver downconverter combines on a single integrated circuit, a first super-heterodyne mixer, a voltage controlled oscillator, a phase locked loop, a pair of quadrature mixers and a pair of quantizers with in-phase and quadrature-phase sampler outputs operable at twenty-five MHz and 2.5 MHz. Emitter-coupled logic and special low-voltage bipolar semiconductor technology are combined for 3.3 volt operation at under one hundred milliwatts.

Abstract: A differential GPS system for precise time and/or location tagging of an event. Reference and rover units cooperate to compensate for delayed availability at the rover unit of error-correction data transmitted via a two-way, high-latency communication link. A reference unit calculates and stores error-correction data. A rover unit collects and stores uncorrected GPS fix data, and transmits a message demanding error-correction data. The message preferably includes a time stamp indicating the time for which the error-correction data is to be valid. In reply to a demand message from a rover unit, the reference unit retrieves stored error-correction data and transmits it to the rover unit via the high-latency communication link. The reference unit includes a time stamp indicating the valid time of the error correction data if the valid time is not implicit in the reply. The rover unit uses the stored, uncorrected GPS fix data and the received error-correction data to compute a differentially-corrected GPS fix.