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: 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: 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.