Abstract: A CDMA receiver for measuring spatial signal information corresponding to several user transmitters comprises a bank of coherent receivers coupled to an antenna array, a bank of signal buffers for recording samples of the received signal data, and a bank of I/Q despreaders for despreading selected signal samples. The receiver also comprises a buffer control circuit for selecting active power control groups in the recorded signal samples for despreading, and a despreader control circuit for selecting PN despreading sequences required to despread the selected power groups. Selected data samples from the signal buffers are fed into the despreaders. The output of the despreaders is a set of spatially correlated I/Q data streams divided into temporal frames, where each frame contains active power control groups from different user transmitters.

Abstract: A system for easily and inexpensively distributing real time location information of cellular telephone users to various third party information subscribers comprises an HTTP server machine which maintains a dynamic database of current cellular users. The database has a list of caller entries, where each entry typically comprises a user ID number, such as a phone number, mobile ID number, and/or handset serial ID. The entry also includes, for each user ID number, a user location identifier such as a latitude and longitude, a sector number, a caller or called phone number and/or a street address. The HTTP server is connected to the internet so that registered third party information subscribers have access to the database by means of standard HTTP protocols that ensure authentication and provide encryption for security.

Abstract: A system for easily and inexpensively distributing real time location information of cellular telephone users to various third party information subscribers comprises an HTTP server machine which maintains a dynamic database of current cellular users. The database has a list of caller entries, where each entry typically comprises a user ID number, such as a phone number, mobile ID number, and/or handset serial ID. The entry also includes, for each user ID number, a user location identifier such as a latitude and longitude, a sector number, a caller or called phone number and/or a street address. The HTTP server is connected to the internet so that registered third party information subscribers have access to the database by means of standard HTTP protocols that ensure authentication and provide encryption for security.

Abstract: A method and apparatus for location finding in a CDMA wireless communication system uses multipath signals in order to accurately determine a transmitter—s location. Direct path and multipath signals from a mobile transmitter arrive at an array of p antennas belonging to a cellular network base station. A location finding apparatus connected to the base station contains a multichannel receiver that uses PN sequence information provided by the base station receiver to despread the p signals and to separate each of the p signals into temporally distinct multipath parts. A signal processor calculates a signal signature for each active mobile. The signature is comprises a code correlation function, a set of temporal delays corresponding to the multipath parts and a set of signal subspaces.

Abstract: A method and apparatus are provided for easily and accurately calibrating an antenna array in a multipath environment. A calibration table containing spatial signature data together with corresponding location data is used to calibrate the antenna array, i.e. to determine the array response in various directions. The calibration table includes a set of calibrated signal covariances R1, . . . , RN together with a set of N corresponding geographical locations. From this data, a set of array calibration vectors {a(&thgr;)} is determined, where each vector a(&thgr;) characterizes the complex signal response of the antenna array in the direction &thgr;. Once the array calibration vectors are determined, this information can be used for direction finding, beamforming, and other enhancements to the performance of the communication system.

Abstract: A method and apparatus for wireless location finding determines a set of likely locations from a signal covariance matrix R, a set of array calibration vectors {a(.theta.)}, and a set of calibrated signal covariance matrices {R.sub.k } corresponding to calibrated locations. From these quantities, an angular energy distribution function B(.theta.) is calculated from R and a(.theta.), and compared to a set of calibrated angular energy distribution functions B.sub.1 (.theta.), . . . , B.sub.N (.theta.) corresponding to the set of calibrated signal covariance matrices R.sub.1, . . . , R.sub.N. The function B(.theta.) is then compared with each of the calibrated functions B.sub.1 (.theta.), . . . , B.sub.N (.theta.) to determine those calibrated functions that most closely match the calculated function B(.theta.). From these calculations a set of likely locations is then determined.

Abstract: A method and apparatus improves the accuracy of a wireless location finding system based on the use of multipath signal signatures. A location finding apparatus measures an array covariance matrix R of a signal. The covariance matrix is compared to a database of signatures comprising calibrated signal subspaces. The comparison is based on calculating the projection of R onto each calibrated subspace. From these calculations a set of likely locations is then determined.

Abstract: A method for determining a geographical location from a measured wireless signal signature comprises calculating from the measured wireless signal signature a multi-dimensional signature vector, wherein each component of the vector measures a degree of coincidence between the measured wireless signal signature and a calibrated signal signature stored in a calibration table. The method also includes matching the signature vector with vectors in a set of multi-dimensional calibrated vectors. The matching uses a procedure comprising searching a hierarchical tree structure and eliminating nodes that cannot contain the best match vector. Within the remaining nodes, the search eliminates individual vectors that cannot be the best match vector, and selects one or more vectors in the set of multi-dimensional calibrated vectors, where the matched vectors correspond to calibrated geographical locations.

Abstract: A system and method is provided for processing a calibration table used in a wireless location finding system. The initial calibration table data comprises points partitioned into routes followed by moving vehicles, where each point comprises a wireless signal signature and corresponding geographical location. The method comprises calculating, for each point, a list of neighboring points; and generating, for each route, a plurality of geographical bins covering all points in the route. Each bin has a bin location and a bin signature derived from those of the points within the bin. The resulting calibration table, which contains fewer redundant data points than the original calibration table data, may be used in a location finding system for quickly identifying the location of wireless transmitters in real time.

Abstract: A method for improving the accuracy of signal signature determinations in wireless location finding systems advantageously uses transmitter velocity estimates to accurately and reliably determine in real time a present signal covariance matrix for a transmitter. In a preferred embodiment of the invention, a method for determining a likely location of a transmitter in a wireless transmitter location finding system comprises coherently measuring transmitter signals received at an antenna array, and calculating a current signal covariance matrix from the measured transmitter signals. The method further comprises calculating an average covariance matrix by forming a linear combination of the current signal covariance matrix with past average covariance matrices.

Abstract: A method and apparatus reduces the ambiguities in the determination of cellular telephone locations in a location finding system based on the use of multipath signals. A location finding base station determines a signal signature from a subspace of an array covariance matrix. The signature is compared to a database of calibrated signal signatures and corresponding locations, and a set of likely locations whose calibrated signatures best match the measured signature is selected. A subset of most likely locations is selected from among the likely locations by comparing a function which represents how closely the measured signature matches the set of calibrated signatures with functions which represent how closely each likely signature matches the set of calibrated signatures. The locations corresponding to the best matching function are selected.

Abstract: A method and apparatus for location finding in a wireless communication system uses multipath signals in order to accurately determine a transmitter's location. Direct path and multipath signals from a mobile transmitter [74] arrive at an antenna array [80, 82, 84] of a base station receiver [76]. The base station determines signal signature from a subspace of an array covariance matrix. The signature is compared to a database of calibrated signal signatures and corresponding locations, and a location whose calibrated signature best matches the measured signature is selected as the most likely transmitter location. The database of calibrated signal signatures and corresponding locations is generated by a calibration procedure in which a phone [74] transmits location data derived from a GPS receiver [88] and GPS satellites [90, 92, 94] to the base station [76] which records the location information together with the signal signature of the transmitter [74].

Abstract: A computer-implemented method for comparing the contents of two sets of documents includes the step of extracting from a set of documents ?44! corresponding sets of document extract entries ?46!. The method further includes a step of generating from the sets of document extract entries ?46! corresponding sets of word clusters ?48!. Each word cluster comprises a cluster word list having N words, an N.times.N total distance matrix, and an N.times.N number of connections matrix. The preferred embodiment includes a step of grouping similar word clusters and combining the similar word clusters to form a single word cluster for each group. The grouping comprises evaluating a measure of cluster similarity between two word clusters, and placing them in a common group of similar word clusters if the measure of similarity exceeds a predetermined value. The step of evaluating cluster similarity comprises intersecting clusters to form subclusters and calculating a function of the subclusters.

Abstract: A multiple access communications system reuses a set of either N carrier frequencies or time slots in adjacent communications sites to provide more than N or T minimally cross-correlated frequency or time hopping communications channels respectively. A first set of communications channels is associated with a first of the communications sites. No two of the channels in the first set employ the same frequency or T time slots at the same time. A second set of communications channels is associated with a second of the adjacent communications sites. No two of the channels in the second set of channels employ the same one of the N carrier frequencies or T time slots at the same time. One or more sets of the minimally cross-correlated channels are further defined so that none of the channels in such sets employ the same frequency at the same time as more than a predetermined number of the channels in another of the sets of the minimally cross-correlated frequency-hopping communications channels.

Abstract: A dynamic image representation system comprising apparatus for sensing a dynamic scene and apparatus for providing a pixel count reduced dynamic digital representation of the scene having pixel count reductions in portions of the scene not fulfilling predetermined spatial criteria and pixel count reductions in portions of the scene not undergoing change within predetermined temporal criteria.

Abstract: This invention is directed to a wide dynamic range video imaging apparatus. More specifically, the invention is directed to a video imaging apparatus comprising a) a sensor for providing a plurality of video images of a scene at different exposure levels and b) a processor for processing the plurality of video images to produce a combined video image including image information from the plurality of video images by applying neighborhood transforms to the plurality of video images, the processor comprising a selector for locally selecting the operating levels of the dynamic range of the combined video image within the dynamic range of the sensor, whereby the resulting video image includes image information from the plurality of video images with enhanced information content at local areas therein.

Abstract: A head position detector system includes a cue definition apparatus arranged to be securely mounted on a head whose position is to be monitored, a single camera electro-optical detector arranged to view the cue definition apparatus, a cue processing apparatus receiving an output of the detector and a memory apparatus for storing updated cue addresses for providing an output indication of head position to utilization apparatus.

Abstract: An intelligent scan image sensor including a two-dimensional solid-state array of addressable imaging cells arranged for exposure to an image, where each cell includes a photosensitive diode and a sample and hold unit. The diode accumulates an electrical quantity having a value in relation to the image light intensity falling thereupon during successive integration periods and the sample and hold unit repeatedly samples and stores the accumulated quantities as analog video data values at the end of each of the successive integration periods.

Abstract: A two-dimensional video data acquisition system comprising: video detector apparatus for scanning a visual scene; controller apparatus for generating scan pattern instructions; system interface apparatus for selecting at least one scan pattern for acquisition of video data from the visual scene, the scan pattern being selected from a plurality of such patterns in accordance with the scan pattern instructions; and scan-video interface apparatus comprising random scan driver apparatus for generating scan control signals in accordance with the selected scan pattern, the video detector apparatus scanning the visual scene in accordance with the scan control signals to provide an output to the system interface such that an intensity data map is stored therein, the controller apparatus performing data processing of the intensity data map in accordance with a predetermined set of video data characteristics.