Abstract: A system and method for identifying objects within a monitored environment includes a plurality of tag signal readers contained within the monitored environment and serially connected along a single connection line as a coaxial cable for receiving tag signals from at least one tag contained within the monitored environment. The tagged signals received by tag signal readers are timed and associated with a particular tag signal reader, such as by the use of multiplexing techniques. A location processor is connected to the single connection line and determines which tag signals are first-to-arrive signals and conduct differentiation of the first-to-arrive signals to locate a tag.

Abstract: An auxiliary wireless communication mechanism is incorporated into a system that geolocates tagged objects within a monitored environment, using random, repetitive spread spectrum emissions from the tags. The emissions are detected at tag emission readers, and processed by an object location processor to geolocate the tagged objects. The auxiliary wireless communication mechanism transmits a return spread spectrum signal containing information intended for a tag immediately in response to the object location processor geolocating the tag. This immediately returned spread spectrum transmission allows a reduced complexity spread spectrum receiver within the tag to despread the return signal without having to determine the timing of the clock signal used to produce it.

Abstract: A wireless local area network and location system for locating objects within a monitored environment are disclosed. A plurality of access point stations receive and transmit communication signals within a wireless local area network. A processor is operatively connected to each of the access point stations and operative for processing communication signals received from the mobile station and, in one embodiment, determining which communication signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals to locate a mobile station. Delayed versions of at least one interference signal are weighted and the amplitude and phase controlled with weighted functions W1, W2. . . Wn. The resultant weighted replicas are summed to determine an approximation of disbursed interference for cancelling interference. The location system can include a tag transmitter and spaced monitoring receivers and processor.

Abstract: A wireless local area network system includes a plurality of access point stations at known locations that receive and transmit communication signals within the wireless local area network. A mobile access point station receives and transmits communication signals within the wireless local area network. A location processor is operatively connected to each of the access point stations and operative to process communication signals transmitted from the mobile access point station and determining which communication signals are first-to-arrive signals based on a common timing signal and conducting differentiation of the first-to-arrive signals to locate the mobile access point station.

Abstract: A magnetic field-based tagged object information storage and retrieval system employs a spread spectrum modulated magnetic field for identifying each of a plurality of tagged objects to which spread spectrum modulation magnetic field transponders are attached. When interrogated by a tag reader, transponders embedded in plural tags generate spread spectrum modulated magnetic fields that are correlated with a reference spreading sequence in a tag reader signal processor to both detect and identify each responding tag.

Abstract: An asset management radio location system uses time-of-arrival differentiation for random and repetitive spread spectrum, short duration transmissions from object-attached tags, to geolocate objects within a monitored environment. An object location processor is coupled to distributed tag transmission readers over signal transport paths having different transport delays, and carries out time-of-arrival differentiation of first-to-arrive transmissions from a tag to determine where its object is located. Geolocation errors associated with variations in parameters of the signal transport paths are effectively removed by installing one or more ‘reference’ tags, whose geolocations are precisely known. Using a background calibration routine that is exercised at a relatively low cycle rate, emissions from the reference tags are processed and coupled to the geolocation processor. The calculated geolocations of the reference tags are compared with their actual locations.

Abstract: A time division multiplexed reader to shared RF channel processor signal transport network for a geolocation system in which the number of readers is relatively small, allowing the use of only a single shared RF channel processor. The differential signal transport delays among respective segments of the network creates an inherent set of time division multiplexed time slots for the various readers, that allows the shared RF channel processor to receive and process the output of each reader in a known, independent time frame.

Abstract: A reader geometry visualization tool for a geo-location system technician's personal computer is operative to display a map of an asset management environment. The technician interactively places and manipulates a distribution of tag transmission readers and any potential impairments to RF transmissions on the map. The locations of the readers (and any impairments) are coupled as input parameters to a mathematical model of a tag-based geo-location system. The performance of the map-parameterized geo-location system model is then computed as a geometric dilution of precision (gdop) value for the intended object coverage area. The computed (gdop) performance is visually characterized on the displayed map, as by way of different colors to indicate how accurately the proposed reader geometry will enable the system to locate objects anywhere in the coverage area.

Abstract: To accommodate the large frequency uncertainty associated with low cost spread spectrum systems, a matched filter architecture is subdivided into cascaded sub-symbol filter segments, the number of which is selected to prevent loss of unacceptable signal energy over the received signal frequency uncertainty. The sub-symbol filter segments are processed in plural phase rotation-signal combiner stages, outputs of which are associated with multiple frequency bins. A respective phase rotation-signal combiner stage multiplies sub-symbol filter segments by respectively offset phase rotation vectors, associated with the plural frequency bins. The sub-symbol phase vector products of each stage are summed to produce plural frequency bin outputs.

Abstract: A non-propagating magnetic field-based communication system transmits and receives digital data within a limited coverage area environment. The system includes a compact transmitter unit, such as that contained in an ‘tracking’ tag affixed to an object, and a digital detector/demodulator unit. In order to generate and FSK-modulate a non-propagating magnetic field in accordance with modulation signals representative of the digital data, the transmitter unit contains a magnetic field coil and one or more capacitors controllably switched in circuit with the coil in accordance with the data, so as to change the resonant frequency of an inductor-capacitor transmitter resonant circuit. The receiver unit includes a magnetic field-sensing coil in circuit with a capacitor, to form a receiver resonant circuit that resonates at a frequency between the FSK frequencies modulated by the transmitter unit.

Abstract: A call tag-based material replenishment system employs a tagged object radio location infrastructure of the type described in the U.S. Pat. No. 5,920,287. For each different part used by a lineside workstation an associated ‘call’ tag is placed at or near that workstation. To initiate replenishment of a part, a ‘call’ push-button on a call tag is operated. In response to the operation of the call button, an RF signal burst containing tag identity and status data is transmitted from the call tag. This information is recovered by a spatially distributed reader and processor subsystem for application to an asset management database. The database associates the call tag's identification data with a particular part, to enable a resource management operator to specify what component is to be accessed from storage and delivered to the requesting call tag's workstation.

Abstract: A tool for augmenting and customizing business transaction processes uses the communication capability and functionality of a geolocation system to embed information associated with a transaction of a tagged object within the spread spectrum signals used to geolocate the object. This enables an ancillary transaction controller, separate from the geolocation system, to focus or target one or more transactions with respect to the tagged object, which may be an individual, such as a customer, patient, client, or the like of an institution in which the geolocation system is installed.

Abstract: A magnetic field excitation and detection coil arrangement is configured to produce an electrical output signal representative of a differential combination of responses from a plurality of magnetic fields, including the field emitted from the excitation coil, a response magnetic field emitted from an object-tagged transponder interrogated by the excitation coil, and other magnetic fields from extraneous sources, such as industrial machinery. This differential combination of the responses from the detection coils will contain only the desired signal (e.g., response from an object-tagged transponder), as the other far away fields cancel, and therefore produces a net output signal level for a downstream signal (transponder output) processor.

Abstract: A distributed radio geo-location and tracking system has a distributed subsystem architecture that distributes its processing workload over a plurality of information handling and processing subsystems. For maximum detection capability, each of a plurality of tag emission receivers is equipped with a circularly polarized, omnidirectional antenna, to provide hemispherical coverage. The receivers are coupled to a partitioned plurality of detection processors, that are coupled via distributed association processors to multiple location processors. Each detection processor demodulates and time stamps received energy correlated to known spreading codes of the tags, to associate received energy with only one tag. It transmits a message containing this information over a communication framework to an association processor.

Abstract: An asset management radio location system uses time-of-arrival differentiation for random and repetitive spread spectrum, short duration pulse `blinks` from object-attached tags, to provide a practical, continuous identification of the location of each and every object within an environment of interest, irrespective whether the object is stationary or moving. Correlation-based RF processors determine which signals received spatially diverse antennas coupled to tag transmission readers are first-to-arrive signals as transmitted from any blinking tag. An object location processor carries out time-of-arrival differentiation of first-to-arrive transmissions from any blinking tag to determine where the respective object is located within the environment.