Abstract: An electronic animal containment system with direction-of-approach determination, or direction-sensitive animal containment system. The direction-sensitive animal containment system generally contains a transmitter unit connected to a wire loop bounding a containment area and a receiver unit carried by the animal. The direction-sensitive animal containment system of the present invention generates a containment field having polarity and retains the polarity information when the containment field is sensed using a sensing coil optimized along the azimuth. The receiver unit also generates a gravity vector to determine the orientation of the receiver unit. The gravity vector is combined with the containment field vector to produce a function that automatically yields a sensing coil output that is independent of the orientation of the receiver unit. The polarity of the sensing coil output allows determination of the direction from which the receiver unit is approaching the wire loop.

Abstract: An electronic animal containment system with direction-of-approach determination, or direction-sensitive animal containment system. The direction-sensitive animal containment system generally contains a transmitter unit connected to a wire loop bounding a containment area and a receiver unit carried by the animal. The direction-sensitive animal containment system of the present invention generates a containment field having polarity and retains the polarity information when the containment field is sensed using a sensing coil optimized along the azimuth. The receiver unit also generates a gravity vector to determine the orientation of the receiver unit. The gravity vector is combined with the containment field vector to produce a function that automatically yields a sensing coil output that is independent of the orientation of the receiver unit. The polarity of the sensing coil output allows determination of the direction from which the receiver unit is approaching the wire loop.

Abstract: A portable animal tracking system. The portable animal tracking system provides two-way communication between a first unit carried by an operator and a second unit carried by an animal. The first unit allows an operator to issue warnings or corrections to an animal and to locate an animal. The second unit delivers warnings and corrections to the animal by the second unit and responds to location requests from the first unit. Location is accomplished through an angular-bearing analysis.

Abstract: A location system includes a plurality of signal readers for receiving signals from a wireless transmitter to be located. The signals include a wideband, spread spectrum signal and a timing marker appended a predetermined time in front of the wideband, spread spectrum signal for indicating the presence of the wideband, spread spectrum signal. A location processor is operatively coupled to the signal readers for detecting the timing markers of signals and responsive to a detection of a timing marker, correlating a signal as a first-to-arrive signal and conducting differentiation of first-to-arrive signals to locate a wireless transmitter.

Abstract: A system of the present invention is operative for locating a wireless mobile device in communication with a wireless local area network (WLAN) that includes a plurality of cells defining a wireless local area network each having an access point base station. The access point base stations communicate with wireless mobile devices using wireless communication signals as typically spread spectrum communication signals. A processor is operatively connected to each of the access point base stations and operative to process communication signals transmitted from a mobile device and determine which signals are first-to-arrive signals based on a common timing signal and conduct differentiation of the first-to-arrive signals to locate the mobile device.

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: 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: An object tracking system for locating radio-tagged objects within a monitored environment has a plurality tag transmission readers that detect RF transmissions from the tags, and generate output signals representative of the time-of-arrival of first-to-arrive tag transmissions. An object location processor processes the first to arrive signals in accordance with a multilateration algorithm to geolocate a tag. In order to modify the operation of a tag that comes within a prescribed region of the monitored environment (such as passing through a doorway), one or more relatively short range, magnetic field proximity-based, tag-programming ‘pingers’, are placed proximate to the region. A magnetic field receiver on the tag detects the field generated by the pinger and causes the tag to change operation such as increase its RF transmission rate.

Abstract: Magnetic field-based communication with an object is enhanced by generating a rotating AC magnetic field that effectively ensures magnetic field coupling with the magnetic field sensor of the object, irrespective of the orientation of the object. The rotating AC magnetic field is produced by a diverse spatial orientation (a two-dimensional arrangement) of a plurality of magnetic field coils, and the driving of those coils in a prescribed phase relationship (e.g., in phase quadrature) to realize a composite AC magnetic field that rotates (at the carrier frequency of the coil drive signal) over the entirety of the spatial coverage area.

Abstract: Magnetic field-based communication with an object is enhanced by generating a rotating AC magnetic field that effectively ensures magnetic field coupling with the magnetic field sensor of the object, irrespective of the orientation of the object. The rotating AC magnetic field is produced by a diverse spatial orientation (a two-dimensional arrangement) of a plurality of magnetic field coils, and the driving of those coils in a prescribed phase relationship (e.g., in phase quadrature) to realize a composite AC magnetic field that rotates (at the carrier frequency of the coil drive signal) over the entirety of the spatial coverage area.

Abstract: An amplitude modulation (AM) based mechanism controllably alters the shape of a binary phase shift keyed (BPSK) digital spreading waveform modulated onto an RF carrier. The modulated RF carrier is amplified by a saturated RF amplifier. The spectral properties of the amplified AM-BPSK waveform, when combined with the spectral properties of a BPSK waveform modulated onto the RF carrier and amplified by another saturated RF amplifier, produces a composite BPSK-modulated RF waveform containing substantially suppressed sidelobes.

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 location system includes a plurality of signal readers for receiving signals from a wireless transmitter to be located. The signals include a wideband, spread spectrum signal and a timing marker appended a predetermined time in front of the wideband, spread spectrum signal for indicating the presence of the wideband, spread spectrum signal. A location processor is operatively coupled to the signal readers for detecting the timing markers of signals and responsive to a detection of a timing marker, correlating a signal as a first-to-arrive signal and conducting differentiation of first-to-arrive signals to locate a wireless transmitter.

Abstract: The unwanted influence a noise-source environment upon a modulated (e.g., FSK-encoded) magnetic field-based communication system is diminished by a non-modulated AC magnetic field communication scheme that uses a demodulatorless magnetic field detector. When installed in a tag to be tracked by a geolocation system, the demodulatorless detector responds when the tag comes within a prescribed proximity of the field generator producing the non-modulated AC magnetic field. The received signal is downconverted to baseband and processed to detect a valid AC magnetic field tone and indicate whether the tag is within a prescribed proximity of the AC magnetic field source.

Abstract: The unwanted influence a noise-source environment upon a modulated (e.g., FSK-encoded) magnetic field-based communication system is diminished by a non-modulated AC magnetic field communication scheme that uses a demodulatorless magnetic field detector. When installed in a tag to be tracked by a geolocation system, the demodulatorless detector responds when the tag comes within a prescribed proximity of the field generator producing the non-modulated AC magnetic field. The received signal is downconverted to baseband and processed to detect a valid AC magnetic field tone and indicate whether the tag is within a prescribed proximity of the AC magnetic field source.

Abstract: A system of the present invention is operative for locating a wireless mobile device in communication with a wireless local area network (WLAN) that includes a plurality of cells defining a wireless local area network each having an access point base station. The access point base stations communicate with wireless mobile devices using wireless communication signals as typically spread spectrum communication signals. A processor is operatively connected to each of the access point base stations and operative to process communication signals transmitted from a mobile device and determine which signals are first-to-arrive signals based on a common timing signal and conduct differentiation of the first-to-arrive signals to locate the mobile device.

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: An object tracking system for locating radio-tagged objects within a monitored environment has a plurality tag transmission readers that detect RF transmissions from the tags, and generate output signals representative of the time-of-arrival of first-to-arrive tag transmissions. An object location processor processes the first to arrive signals in accordance with a multilateration algorithm to geolocate a tag. In order to modify the operation of a tag that comes within a prescribed region of the monitored environment (such as passing through a doorway), one or more relatively short range, magnetic field proximity-based, tag-programming ‘pingers’, are placed proximate to the region. A magnetic field receiver on the tag detects the field generated by the pinger and causes the tag to change operation such as increase its RF transmission rate.

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.