Abstract: A tag includes a housing, an antenna disposed within the housing, and circuitry within the housing that is electrically coupled to the antenna. A battery within the housing is electrically coupled to the circuitry, the battery being positioned so as to avoid significant interference with electromagnetic fields associated with the antenna. A tag holder can be detachably coupled to a radio frequency tag, and has structure facilitating attachment of the tag holder to an object other than a tag. A tag includes a circuit and an antenna, the antenna having a plurality of conductive segments and capacitors that are coupled in series to form an endless loop.

Abstract: An intrusion detection technique involves: emitting a wireless signal within a container; detecting the wireless signal near the container; and responding to detection of a change in a characteristic of the detected wireless signal by transmitting a wireless notification to a location remote from the container. A different technique involves: responding to a determination that a condition representative of unauthorized intrusion is present while the container is stationary by transmitting a wireless notification; and responding to a determination that the container is moving by ignoring whether the condition is present. Yet another technique involves: monitoring whether a door of a container is in a closed position; and emitting a wireless signal indicating whether the container door is in the closed position.

Abstract: An intrusion detection technique involves: emitting a wireless signal within a container; detecting the wireless signal near the container; and responding to detection of a change in a characteristic of the detected wireless signal by transmitting a wireless notification to a location remote from the container. A different technique involves: responding to a determination that a condition representative of unauthorized intrusion is present while the container is stationary by transmitting a wireless notification; and responding to a determination that the container is moving by ignoring whether the condition is present. Yet another technique involves: monitoring whether a door of a container is in a closed position; and emitting a wireless signal indicating whether the container door is in the closed position.

Abstract: A device (12) facilitates sealing and tracking of a container (18). The device includes a bolt (166) which extends through openings in a latch mechanism (19) on the container. The bolt also passes through spaced coils (251, 252) of the seal device. The seal device uses one coil to generate a magnetic field, while monitoring the corresponding magnetic field induced in the other coil. Tampering with the bolt affects the magnetic field, which in turn permits the seal device to detect the tampering. The seal device periodically transmits wireless signals (71), which can be remotely received for purposes of tracking the container and monitoring the integrity of the seal.

Abstract: A communication system that communicates for locating one or more tags in a time and energy efficient manner. The tags are positioned in a communication region and are located by a locator. The tags are located through organized transmission and reception of signals between the tags and the locator. The locator locates and gives directions to tags from the locator using a radio link and a multi-channel ultrasonic acoustic link. The combination of linkages provides the means to determine the unobstructed bearing and distance between the locator and the tag and resolves multipath reflections.