Abstract: Techniques for accurate position location and tracking suitable for a wide range of facilities in variable environments are disclosed. In one aspect, a system for position location comprises a plurality of sensors (e.g. a network monitor, an environment sensor) for generating a measurements of a plurality of sources, a plurality of objects or tags, each object generating measurements of the plurality of sources, and a processor for receiving the measurements and generating a position location for one or more objects in accordance with the received measurements. In another aspect, a position engine comprises a mapped space of a physical environment, and a processor for updating the mapped space in response to received measurements. The position engine may receive second measurements from an object within the physical environment, and generate a position location estimate for the object from the received second measurements and the mapped space. Various other aspects are also presented.

Abstract: Location of mobile units in a wireless local area network is based on use of signal strength ratios and other criteria. In one embodiment absolute value of signal strength is used to derive a second value of location. The second value may be used as the location if the system is not calibrated and may also be used to calibrate the system. Alternatively time difference of arrival may be used in combination with signal strength ratio.

Abstract: An apparatus for determining a position of a mobile wireless station comprises means for determining the position of the mobile wireless station in accordance with a position of a first reference wireless station, a position of a second reference wireless station, a first relative angular direction between the mobile wireless station and the first reference wireless station, and a second relative angular direction between the mobile wireless station and the second reference wireless station.

Abstract: The invention relates to a method and a system for determining the position of a device (1) by taking measurements to determine the range between at least a first positioning station (2) and the device (1) and to determine the range between at least a second positioning station (3) and the device (1). At least one measurement defines a geometric surface for the position of the device (1). Said first positioning station (2) and second positioning station (3) belong to different systems. In the invention, the measurements are used to select a geometric model which comprises, at the most, quadratic surfaces, the selected geometric model is simplified to reduce the number of quadratic surfaces, the measurement results are inserted in the simplified geometric model, and the position of the device (1) is determined by solving the simplified geometric model. The invention also relates to a device (1) and a program in which the method is applied, as well as to a storage means for storing the program.

Abstract: Available-satellite data indicating satellites available for satellite positioning is obtained from a GPS receiver, and satellites continuously available for satellite positioning in the current instance and the previous n times are extracted as candidate satellites referring to available-satellite record data. Four of the candidate satellites are selected so that the satellites used for satellite positioning the previous time are selected with priority as the satellites to be used for satellite positioning in the current instance, and the selected satellites are set in designated-satellite data. The GPS receiver performs three-dimensional positioning using the four satellites designated by the designated-satellite data. If the number of extracted candidate satellites is three, these three extracted candidate satellites are selected as the designated satellites and are set in the designated-satellite data. The GPS receiver performs two-dimensional positioning using these three designated satellites.

Abstract: Apparatus and method for resolving repeater location ambiguities in a CDMA network using a CDMA Time Pseudolite. The CDMA Time Pseudolite includes a CDMA receiver to receive a CDMA signal with an embedded CDMA timing, a baseband processor to extract the CDMA timing and to adjust the CDMA timing to derive a signal with GNSS-like timing; and a GNSS transmitter to generate a GNSS-like signal and to transmit the GNSS-like signal to a mobile station. In one embodiment, the CDMA Time Pseudolite is situated at or nearby a CDMA signal repeater so that a mobile station may unambiguously identify a received CDMA signal as being transmitted by a particular CDMA signal repeater and then using that received CDMA signal for position determination of the mobile station.

Abstract: A complete positioning solution for mobile communications networks such as WLAN or ad-hoc/multi-hop networks, which lack location information for one or more base stations. A method and arrangement computes the locations and transmit timing of the base stations utilizing GPS location information and GPS timing information from multiple GPS-capable mobile stations operating in the service areas of such base stations. Once the base station locations and transmit timing are known, this information is used in conjunction with the reported GPS information to synchronize transmissions from the base stations using a marker in a downlink transmission such as the start of a particular frame. Finally, the locations and transmit timing from three or more base stations are used to determine the locations of mobile stations that are not GPS-capable.

Abstract: A method to detect and/or locate a mobile craft in a reception system making use of transmitters of opportunity, whose signal comprises elements enabling the synchronization of the receiver, wherein certain discriminating sequences are detected of the payload signal. Each transmission present on the carrier frequencies examined by the receiver or receivers is separated by the space/time filtering of the signals in each carrier frequency. The transmitters Ei corresponding to the signals received are identified. The pulse response of the propagation channel for each transmitter Ei and for each detection made on this transmitter are determined by measuring the instant of arrival of the path reflected by the mobile craft is measured and then its delay relative to the instant of transmission from the transmitter. The position of the mobile craft is deduced at the intersection of the ellipsoids defined by the foci constituted by the transmitters Ei from which signals are received and the receiver or receivers Rj.

Abstract: A method for positioning a wireless communication device where position data of one or a plurality of reference points is stored into at least one data base, and which of the reference points is located in the vicinity of the wireless communication device is determined. The method also includes transmitting at least position data of the reference point located in the vicinity of the wireless communication device to the wireless communication device and selecting the reference point located in the vicinity of the wireless communication device as the default location of the wireless communication device.

Abstract: In a local positioning system, augmentation of the land-based system is provided by receiving signals from a GNSS. The signals from the land-based positioning system have a code phase accuracy better than one wavelength of a carrier of the signals from the GNSS. Different decorrelation may be used for signals from a satellite than from a land-based transmitter, such as using a digital decorrelator for signals from the satellite and an analog decorrelator for signals from a land-based transmitter. The receivers may include both a GNSS antenna and a local antenna. The phase centers of the two antennas are within one wavelength of the GNSS signals from each other. The local antenna is sized for operation in the X or ISM-bands of frequencies. The GNSS antenna is a patch antenna where the microwave antenna extends away from the patch antenna in at least one dimension.

Abstract: A receiver (1) of a position-finding system comprises a calculation unit (6, 7, 8) for calculation of a statistical value (?) on the basis of a received signal, and a detector unit (9) for comparison of the statistical value (?) with a threshold value (?) and for determining whether the received signal is a synchronized location signal, an estimation unit (10) for estimation of the Rice factor (K) of the radio link via which the received signal has been transmitted, and a determination unit for calculation of the threshold value (?) on the basis of the Rice factor (K).

Abstract: A multistatic radar has a radar transmitter for illuminating a target with a radar signal. The target reflects the radar signal to three separate radar receivers, each performing a bistatic range measurement to the target. The three bistatic range measurements are combined in a quadratic equation having two solutions (roots). One solution (root) corresponds to a correct three dimensional target position with respect to the radar transmitter while the other is an incorrect three dimensional target position with respect to the radar transmitter. The incorrect three dimensional target position is identified and eliminated by comparing the three dimensional target position to the transmitter location, and the receiver locations. The incorrect three dimensional target position is also identified by the target altitude exceeding a threshold, typically set above 80,000 feet AGL.

Abstract: In a local positioning system, a receiver is adapted for receiving signals from a land-based transmitter. The receiver includes an analog decorrelator for decorrelating the transmitted spread spectrum signals. A down converter connected with an antenna may be spaced away from other portions of the receiver. The down converter down converts received ranging signals and provides them to the remotely spaced receiver portions. A signal line connecting the down converter to the receiver may be operable to transmit any two or more of a reference signal provided to the down converter, the down converted intermediate frequency signals provided to the receiver, and power provided to the down converter. The receiver may be positioned adjacent to or as part of a land-based transmitter. By determining positions of two or more antennas, the location of the associated transmitter is determined.

Abstract: A location system for locating and determining the motion and velocity of a wireless device. The methods include direct inferences about whether a device is in motion versus static based on a statistical analysis of the variation of radio signal strengths over time. The system is trained according to a sparse set of identified locations from which signal strengths are measured. The system uses the signal properties of the identified locations to interpolate for a new location of the wireless device. The system uses a probabilistic graph where the identified locations of the floor plan, expected walking speeds of pedestrians, and independent inference of whether or not the device is in motion are used to determine the new location of the device.

Abstract: An apparatus for determining a position of a mobile wireless station comprises means for determining the position of the mobile wireless station in accordance with a position of a first reference wireless station, a position of a second reference wireless station, a first relative angular direction between the mobile wireless station and the first reference wireless station, and a second relative angular direction between the mobile wireless station and the second reference wireless station.

Abstract: A method and apparatus for locating position of a GPS device is described. In one example, a wireless carrier is provided in communication with the GPS device. The wireless carrier is configured to provide an approximate position of the GPS device. A server is provided for generating an initialization packet having a satellite orbit model configured for the approximate position. The GPS device is configured to compute pseudo-noise code phase information using the satellite orbit model of the initialization packet. The server is configured to compute position of the GPS device using the pseudo-noise code phase information. A web portal is provided to facilitate communication among the GPS device, the wireless carrier, and the server. In one example, a position request is generated at the web portal. In another example, the position request is generated at the GPS device.

Abstract: A technique for geolocating (mobile) objects within an environment where other locating systems, such as GPS-based systems, may not be expected to operate successfully, uses at least three transmitter sites whose geolocations are fixed and known, and which transmit dual frequency beacons that are readily received by a mobile receiver within the environment of interest. The object's receiver processes the three sets of received signals by measuring the phase differences among respective pairs of the beacons, and then processes these phase differences to perform time difference of arrival-based or time of arrival-based distance information to locate the object relative to the beacons sites. Phase errors or offsets are readily calibrated out, to realize geolocation information at the mobile receiver.

Abstract: A method and computer program product for determining the position of a user terminal includes receiving at the user terminal a plurality of digital television (DTV) broadcast signals from a plurality of DTV transmitters, wherein each of the DTV signals is a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; determining a pseudo-range between the user terminal and each DTV transmitter based on the DTV broadcast signals based on a known component in the DTV signals; and determining a position of the user terminal based on the pseudo-ranges and a location of each of the DTV transmitters.

Abstract: The present invention concerns a method of determining the position of a mobile station in a mobile telecommunication network, the said network including a plurality of base stations designed to adopt at least on the one hand a state corresponding to periods of transmission of signals useful to the determination of the said position, the said mobile station, on reception of the said useful signals, making measurements of quantities of the said useful signals which are characteristic for using a position determination method and on the other hand a state corresponding to periods of silence during which no signal is transmitted. According to the present invention, the said method consists of providing means so that the said periods of transmission and the said periods of silence are arranged in cycles including at least one period of silence, the cycle allocated to a base station being identical to the cycle allocated to any base station adjacent to it, but is offset from it in time.

Abstract: Systems and methods for determining location by implication are described. A responsive environment includes a location determination method that operates in an area that is only partially instrumented with location-sensing devices. Some of the with location-sensing devices sense location ambiguously. For example, a location-sensing device may be deployed at a boundary between two target objects or areas of interest. The location of the target object, as reported by such devices, is considered ambiguous. While the object or person is known to be in a space, it is not clear which specific space. The location of ambiguously located objects can be disambiguated based on changes in the location of other objects. For example, if a document is placed on a shelf in an office, such action strongly implies that someone is in the office. Therefore, if a person is known to potentially be in the office or the outside hallway, the person's location is changed to be in the office.

Abstract: The invention relates to a receiver in a position-finding system, having a calculation unit for calculating a statistical value from a received signal, and a detector unit for comparing the statistical value with a threshold value and for determining whether the signal is a synchronized position-finding signal. The system also includes an estimation unit for estimating the quotient of the signal-carrier power and the noise-power spectral density of the signal, and a determination unit for threshold-value determination from the estimated quotient.

Abstract: A device for determining the position and/or orientation of a creature (3) relative to an environment, comprising a locating member (4) connected to the creature (3), the locating member including a transducer (5) arranged to determine its position and/or orientation relative to the environment by receiving incident signals from signal sources (9) in the environment and record the relative incident directions of the signals received in relation to the transducer, and an element (8) by which the creature (3) and the transducer (5) are connected to each other, so that the relative positions and/or orientations of the creature (3) and the transducer (5) are arranged to be within a limited interval, for determining the position and/or orientation of the creature (3) by the information about the position and/or orientation of the transducer (5).

Abstract: A method, apparatus, and computer-readable media for determining the position of a user terminal comprises receiving, at the user terminal, a digital audio broadcast signal; and determining a pseudo-range between the user terminal and a transmitter of the digital audio broadcast signal based on a known component of the digital audio broadcast signal; wherein the position of the user terminal is determined based on the pseudo-range between the user terminal and the transmitter of the digital audio broadcast signal and a location of the transmitter of the digital audio broadcast signal.

Abstract: A method for providing directions includes receiving at a server, from at least one fixed wireless communication device, information identifying a current location of a portable communication device. The portable communication device has short range wireless communication capability. The at least one fixed wireless communication device is located within a building. The method further includes identifying a direction of movement to be communicated to the portable communication device to direct it towards a destination within the building. The method also includes transmitting the direction of movement to the portable communication device from the server via a fixed wireless communication device.

Abstract: A location discovery method using location data items that originate at known locations (X,Y) and are passed to, and diffused between, entities (A,B) by short-range communication. Each location data item received by an entity (A,B) indicates a maximum distance of the entity from one of the known locations (X,Y). Each entity (A,B) prior to using a location data item for location determination or transferring it to another entity, is operative to increase the maximum distance indicated by the location data item to take account of movement of the mobile entity since receiving that item. A mobile entity (A) effects location determination by finding locations (40) simultaneously consistent with the maximum distances (31,36) it knows of and any applicable route constraints for how the location data items passed to the mobile entity.

Abstract: Apparatus and methods for resolving integer ambiguities in position determination. An embodiment of the invention includes a reference system, augmented with multi-frequency pseudolites using a carrier phase differential GPS implementation, and a mobile system. In one embodiment, the components of the reference system includes one or more multi-frequency pseudolites, one or more multi-frequency reference receivers, a data link standing alone or built into the pseudolites, and the associated antennae for each of these elements. The components of the reference system may be stationary. The mobile system may include a multi-frequency receiver and its associated antennae. Because the mobile systems may passively receive information, an unlimited number of mobile systems may be included in any given embodiment of the invention.

Abstract: A method to determine position of a user includes sniffing for one or more earth-based media; and if the one or more earth-based media exists, using an earth-based positioning system (PS) receiver associated with one of the media and otherwise using a satellite-based PS receiver.

Abstract: The present invention is directed to a system and method for Doppler track correlation for debris tracking in PCL radar applications. The disclosed embodiments describe the systems and methods used in the detection of debris pieces and the association of the Doppler signals from the debris pieces across multiple illumination channels. The present invention also provides computation of debris state vectors and the projection of trajectories to determine debris impact points.

Abstract: A method, apparatus, and computer-readable media comprising generating a positioning signal comprising a first half-field and a second half-field; and transmitting the positioning signal; wherein each of the first and second half-fields comprises 313 segments; and wherein each of the segments comprises 832 chips comprising an American Television Standards Committee (ATSC) digital television (DTV) segment synchronization signal and a pseudonoise sequence.

Abstract: A computer program product, apparatus, and method for determining the position of a user terminal. It includes receiving, at the user terminal, a broadcast analog television signal having a periodic component; and correlating the broadcast analog television signal with a predetermined reference signal based on the periodic component, thereby producing a pseudorange; and wherein the location of the user terminal is determined based on the pseudorange and a location of the transmitter of the broadcast analog television signal.

Abstract: Mobile station positioning methods are calibrated using an error bias estimation for refining the determination of the mobile station location which does not require any added hardware to the telecommunications system. The position of the mobile station is calculated assuming no bias errors and a first order approximation of the mobile station position is derived as a function of the bias error. The bias error is then estimated and used to refine the previously calculated mobile station position.

Abstract: A system and method for rapidly determining the source of an incoming projectile applies controlled, active RF energy source(s) to illuminate a target area/projectile, and exploits Doppler induced frequency shifts from multiple receivers to develop a vector solution. The preferred solution applies continuous wave (CW) RF illuminators to flood a local region with a controlled source of radio frequency energy and one or more displaced receiver elements. The system operates multi-statically and as an incoming projectile enters the illuminated region, reflected energy from one or more illuminators is detected by one or more displaced RF receivers. Doppler shifts imparted on the reflected signals are detected by the receivers as the projectile moves through the region. Appropriate processing of the receiver outputs generates Doppler time-frequency profiles that are used to derive an estimate of the projectile flight vector in 3-space (x,y,z).

Abstract: A method, apparatus, and computer-readable media for determining the position of a user terminal comprises receiving at the user terminal a digital television (DTV) broadcast signal from a DTV transmitter, wherein the DTV signal comprises an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal; determining a pseudo-range between the user terminal and the DTV transmitter based on a known component in the broadcast DTV signal; and determining a position of the user terminal based on the pseudo-range and a location of the DTV transmitter.

Abstract: The present invention relates to communication improvements between a mobile device (12) and backend system (20) applications. A special purpose server computer—a Device Registry Server (18)—is switched between a large variety of different mobile device types (12) and a plurality of backend systems (20) for improving the communication between a mobile device and a backend system. The server (18) stores information usable for facilitating communication setup, operation and maintenance of device applications. Preferably, a ready-to-use, already customized device-type specific application can be downloaded from said server (18) to a variety of different mobile devices which is then used for easily communicate with any desired backend system (20).

Abstract: Systems and techniques for location determination. A plurality of tags emitting radio frequency signals are dispersed throughout a region, such as a building, within which a user's location is to be determined. The radio frequency signals emitted by the tags include information that can be used to identify the location in which the tags axe placed, or simply to distinguish the tags from one another. A portable device receives signals from the tags and provides the signal information to a location server that computes the location of the portable device by comparing the signal information received from the portable device to a map of location venus stored signal information, and identifies the location of the portable device as the location for which the stored signal information best matches the signal information received from the portable device.

Abstract: The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling device (204, 205, 206) for each transmitter (201, 202, 203), which sends to the computing device (208) a representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminal (207) with the representation sent back by the sampling device in the brightest transmitter is performed in the computing device (208), and an estimate of that brightest signal is subtracted from the representation sent back by the mobile terminal (207) in order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

Abstract: The invention relates to a method for estimating the position of a receiver receiving code modulated signals from at least one beacon. The method comprises delimiting a region containing the receiver position based on a code modulated signal received at the receiver from at least one beacon and on available information including at least an initial information on the receiver position. The method further comprises estimating the receiver position as a position within the delimited region which minimizes an error criterion. The invention relates equally to such a receiver, to a system comprising such a receiver and to a corresponding software program product enabling an estimation of the position of a receiver.

Abstract: Apparatus and methods for resolving integer ambiguities in position determination. An embodiment of the invention includes a reference system, augmented with multi-frequency pseudolites using a carrier phase differential GPS implementation, and a mobile system. In one embodiment, the components of the reference system includes one or more multi-frequency pseudolites, one or more multi-frequency reference receivers, a data link standing alone or built into the pseudolites, and the associated antennae for each of these elements. The components of the reference system may be stationary. The mobile system may include a multi-frequency receiver and its associated antennae. Because the mobile systems may passively receive information, an unlimited number of mobile systems may be included in any given embodiment of the invention.

Abstract: A method and system for determining a geolocation of an object includes collecting a positioning signal including a predetermined message data segment. A time of arrival of the predetermined message data segment may be determined in the positioning signal. Information based on the time of arrival may be provided for determination of a geolocation of an object. The time of arrival of the predetermined message data segment may be determined based on a time search for the predetermined message data segment in the positioning signal.

Abstract: A system and method of estimating the position of a mobile terminal (MT) operating in a radio telecommunications network. Expected Received Signal Strength (RSS) values are predicted by a computer-aided prediction tool, and/or are measured by a test MT from base station transceivers. The predicted and measured RSS values are then tagged to indicate whether each value was predicted or measured. The RSS values are then stored at a plurality of locations in a database. When RSS measurements are received from the MT being located, a covariance matrix is used to compute metrics for the locations in the database. If more than a threshold percentage of the locations were populated with measured values, a Maximum-Likelihood (ML) estimator is used to estimate the position of the MT. If fewer than the threshold percentage of locations were populated with measured values, a Minimum-Mean-Square-Error (MMSE) estimator is used to estimate the position.

Abstract: Techniques to estimate the position of a wireless terminal. In a method, the identities of a number of transmitters (e.g., BTSs) to be used to estimate the position are initially received. Expected areas for these transmitters are then determined. The expected area associated with each transmitter is indicative of an area where the terminal is likely to be located given that the signal from the transmitter is received by the terminal. Each expected area may comprise a location (e.g., the expected area center) to be used as an estimated position of the terminal and an uncertainty (or error estimate) associated with that estimated position. The expected areas for the transmitters are then combined (e.g., based on a weighted average) to determine a combined expected area, which is then provided as the estimate of the position of the terminal.

Abstract: A computer program product, apparatus, and method for determining the position of a user terminal. It includes receiving at the user terminal a plurality of digital television (DTV) broadcast signals from a plurality of DTV transmitters, determining a pseudo-range between the user terminal and each DTV transmitter based on the DTV broadcast signals, and determining a position of the user terminal based on the pseudo-ranges and a location of each of the DTV transmitters.

Abstract: A method, apparatus, and computer-readable media for determining the position of a user terminal comprises receiving at the user terminal a broadcast television signal from a television signal transmitter; determining a first pseudo-range between the user terminal and the television signal transmitter based on a known component of the broadcast television signal; receiving at the user terminal a mobile telephone signal from a mobile telephone base station; determining a second pseudo-range between the user terminal and the mobile telephone base station based on a known component of the mobile telephone signal; and determining a position of the user terminal based on the first and second pseudo-ranges, a location of the television signal transmitter, and a location of the mobile telephone base station; wherein the mobile telephone signal is selected from the group consisting of a EDGE (Enhanced Data Rates for Global System for Mobile Communications (GSM) Evolution) signal; a Code-Division Multiple Access 2000

Abstract: A wireless means of guidance for a device in accordance with the present invention includes receiving signals from at least one wireless base station indicating at least a respective position thereof, determining the current position of the device using at least the information contained in the received signals, calculating a vector between the determined current position and a predetermined desired destination for the device, and making trajectory corrections to the device's current trajectory so as to guide the device to the desired destination. In addition to the information contained in the received signals, the guidance system may also use stored information regarding parameters, such as the location, communication protocols and operating frequencies of the wireless base stations, as well as previous position information, for determining a current position for the device.

Abstract: A method for location determination using Bluetooth techniques is applicable within buildings, underground or within other structures. A mobile unit (10) seeks the location of a cell from location master (20). Location master (20) and a number of location subsidiaries (21-24) determine ranging information with regard to the mobile unit (10) using Bluetooth techniques. The location master (20) then determines the mobile unit location using least squares estimation or other triangulation methods (50). In an alternate embodiment, ranging information is fine tuned for noise and error measurements between the location master and the location subsidiaries (51, 53) are used.

Abstract: System and methods are disclosed for employing one or more radiators having non-unique phase centers mounted to a body with respect to a plurality of transmitters to determine location characteristics of the body such as the position and/or attitude of the body. The one or more radiators may consist of a single, continuous element or of two or more discrete radiation elements whose received signals are combined. In a preferred embodiment, the location characteristics are determined using carrier phase measurements whereby phase center information may be determined or estimated. A distributed antenna having a wide angle view may be mounted to a moveable body in accord with the present invention. The distributed antenna may be utilized for maintaining signal contact with multiple spaced apart transmitters, such as a GPS constellation, as the body rotates without the need for RF switches to thereby provide continuous attitude and position determination of the body.

Abstract: A method, apparatus, and computer-readable media for determining the position of a user terminal comprises receiving at the user terminal a broadcast television signal from a television signal transmitter; determining a first pseudo-range between the user terminal and the television signal transmitter based on a known component of the broadcast television signal; receiving at the user terminal a mobile telephone signal from a mobile telephone base station; determining a second pseudo-range between the user terminal and the mobile telephone base station based on a known component of the mobile telephone signal; and determining a position of the user terminal based on the first and second pseudo-ranges, a location of the television signal transmitter, and a location of the mobile telephone base station; wherein the mobile telephone signal is selected from the group consisting of a EDGE (Enhanced Data Rates for Global System for Mobile Communications (GSM) Evolution) signal; a Code-Division Multiple Access 2000

Abstract: A location determination apparatus, method and system (10, 23, 26, 32, 36, 48, 52, 60, 64, 74, 78, 84, 90, 106) that is an improvement upon existing location determining techniques. The invention enables precision indoor location determination through the use of non-DTV terrestrial broadcast signals (e.g. one way, wide area, dissemination of information)(20), or re-broadcast signals (44, 56, 70, 80) of the proposed (terrestrial based) digital satellite radio relay transmitters (42, 54) to provide position location. This solution does not require a local receiver to correct for long distance propagation dispersion, particularly for the satellite relay, as the digital radio satellites are already synchronized to GPS time.

Abstract: The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling device (204, 205, 206) for each transmitter (201, 202, 203), which sends to the computing device (208) a representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminal (207) with the representation sent back by the sampling device in the brightest transmitter is performed in the computing device (208), and an estimate of that brightest signal is subtracted from the representation sent back by the mobile terminal (207) in order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

Abstract: Positioning system for locating a mobile body comprising a plurality of earth based spread spectrum (SS) broadcasting stations arranged geographically in a cellular pattern. Each SS broadcasting station include a modulator providing a channel signal structure which is substantially orthogonal with respect to adjacent stations in the cellular pattern, each channel signal including navigation beacon data including a unique beacon identification, station latitude and longitude, time_slot and phase characterizations and selected parameters of adjacent stations. In one embodiment, each modulator provides a chirped SS signal in which the navigation beacon is a frequency tone that is repeatedly swept over a selected frequency band for each station. In a further embodiment, each modulator provides a GPS like direct sequence SS signal in which the navigation beacon is a PN coded broadcast.