Abstract: A tag can receive first and second wireless signals respectively defining first and second transmission fields that overlap. When the tag moves from the first field to the second field through the region of overlap, the apparatus transitions only once from recognizing the tag is in the first field to recognizing the tag is in the second field. According to another aspect, first and second signposts are supported at spaced locations in the region of a crane, and respectively transmit first and second wireless signals that are different, and that respectively define first and second fields of transmission. According to yet another aspect, a signpost transmits wireless signals having a transmission field, and a system senses positional information regarding a tag movable relative to the signpost, the system using the positional information to determine a location of the tag in relation to the transmission field.

Abstract: An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) that are received by a tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711). The tag in turn transmits radio frequency beacon signals (72) which are received by a reader (13, 261, 319, 521-530). The tag can vary the duration of the beacon signals, for example in dependence on whether it is currently receiving a signpost signal. Further, the tag can dynamically vary the transmission rate and/or transmission power of the beacon signals, for example following receipt of a signpost signal. Varying these parameters can facilitate compliance with governmental regulations.

Abstract: One aspect of the invention involves: monitoring a voltage of a battery over time; evaluating whether a rate of voltage decrease of the battery is in excess of a threshold; and indicating that the battery is subject to a low voltage condition when the rate of voltage decrease exceeds the threshold. Another aspect of the invention involves: causing a circuit powered by a battery to respond to battery replacement by thereafter applying a selected load to the battery during a selected time interval. A further aspect involves: periodically sampling a voltage of a battery; and applying a load to the battery during a selected time interval before each sampling of the battery voltage.

Abstract: A tag receives wireless signpost signals that include timing data, determines time information associated with an event as a function of the timing data, and transmits a wireless tag signal that contains the time information. In a another configuration, a signpost transmits wireless signpost signals having a selected transmission range; a reader proximate to the signpost receives wireless tag signals with a reception range that is approximately the same as the selected transmission range; and a tag movable relative to the signpost and reader responds to receipt of a wireless signpost signal by transmitting a wireless tag signal containing a tag code associated with the tag.

Abstract: One aspect of the invention involves: maintaining a record of how long a circuit operates in each of a plurality of different operating modes thereof, starting from a point in time at which a battery that powers the circuit is replaced; calculating for each of the operating modes as a function of the record a cumulative current drain from the point in time to a current time; and determining as a function of the cumulative current drains whether the battery is subject to a low voltage condition. Another aspect involves: monitoring a voltage of a battery; periodically determining whether the voltage of the battery is subject to a low voltage condition; and maintaining a count of the number of times that the determining results in a determination that the battery is subject to a low voltage condition.

Abstract: A tag stores information identifying the sequence in which it received wireless signpost signals from different signposts. In another configuration, a tag maintains data identifying a group of signposts that are to be treated as equivalent. In yet another configuration, wireless signpost signals transmitted by each of a plurality of signposts all contain the same signpost code. In still another configuration, a signpost has an interface through which a signpost code of the signpost can be selectively set.

Abstract: A tag can transmit a tag signal, and responds to receipt of a wireless signpost signal by determining whether the signpost that generated the signal is currently active. When the signpost is respectively determined to be active and inactive, the tag respectively includes and excludes from the tag signal an information portion that relates to the signpost that generated the received signpost signal. In another configuration, a tag has first and second antennas, receives wireless signpost signals through at least one of the antennas, and responds to receipt of a signpost signal containing antenna select information by causing a selected one of the first and second antennas to be disabled and the other of the first and second antennas to receive wireless signpost signals.

Abstract: A tag has circuitry that can transmit and receive wireless signals, including receipt of first and second wireless signals that are different. The circuitry responds to a predetermined event by inhibiting wireless transmissions for up to a selected time interval, while waiting for receipt of one of the first and second wireless signals. The circuitry responds to receipt during the selected time interval of one of the second wireless signals before receipt of one of the first wireless signals by continuing to inhibit wireless transmissions, and responds to expiration of the selected time interval without receipt of either of the first and second wireless signals by transmitting a selected wireless signal.

Abstract: A tag receives a wireless signpost signal that contains a signpost code, converts the signpost code into location information representative of a physical location of a signpost that transmitted the received signpost signal, and transmits a wireless tag signal that includes the location information. In a different configuration, a tag receives a wireless signpost signal that includes a signpost code, and determines whether the signpost that generated the received signpost signal is a replacement for a different signpost. If it is a replacement, the tag transmits a wireless tag signal containing an information portion that relates to the signpost replaced by the signpost that generated the received signpost signal.

Abstract: A tag has circuitry with a communication portion that can transmit and receive wireless signals, including wireless transmission of data blocks that each have a predefined configuration with a plurality of data slots. The circuitry includes a further portion that, in response to receipt through the communication portion of a wireless communication containing a request identifying a set of plural data items, populates respective data slots in one data block with respective data items from the set, and then causes the communication portion to effect wireless transmission of that data block.

Abstract: One aspect of the invention involves: periodically sampling a voltage of a battery and an ambient temperature in order to obtain a sample that includes a temperature value and a voltage value; saving each sample in a sample group; selecting a subset of the samples in the group, wherein the temperature value of each sample in the subset is lower than the temperature value of substantially all of the samples of the group other than the subset; and determining as a function of the voltage of at least one the sample in the subset whether the battery is subject to a low voltage condition.

Abstract: A tag can receive first and second wireless signals respectively defining first and second transmission fields that overlap. When the tag moves from the first field to the second field through the region of overlap, the apparatus transitions only once from recognizing the tag is in the first field to recognizing the tag is in the second field. According to another aspect, first and second signposts are supported at spaced locations in the region of a crane, and respectively transmit first and second wireless signals that are different, and that respectively define first and second fields of transmission. According to yet another aspect, a signpost transmits wireless signals having a transmission field, and a system senses positional information regarding a tag movable relative to the signpost, the system using the positional information to determine a location of the tag in relation to the transmission field.

Abstract: An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) that are received by a tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711). The tag in turn transmits radio frequency beacon signals (72) which are received by a reader (13, 261, 319, 521-530) The tag can vary the duration of the beacon signals, for example in dependence on whether it is currently receiving a signpost signal. Further, the tag can dynamically vary the transmission rate and/or transmission power of the beacon signals, for example following receipt of a signpost signal. Varying these parameters can facilitate compliance with governmental regulations.

Abstract: An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) to a tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711), which in turn transmits beacon signals (72) to a reader (13, 261, 319, 521-530). One of the signpost and tag is mounted on an item to be tracked. A control system (14, 500) is responsive to the reader, and can cause the signpost to vary the signpost signal in a manner which varies at least one operational characteristic of the tag, such as a transmission rate, a transmission power, a tag identification code, a password, or an encryption code, or which shifts the tag between a normal operational mode and a low power operational mode in which its transmitter is disabled.

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: An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) to a tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711), which in turn transmits beacon signals (72) to a reader (13, 261, 319, 521-530). One of the signpost and tag is mounted on an item to be tracked. A control system (14, 500) is responsive to the reader, and can cause the signpost to vary the signpost signal in a manner which varies at least one operational characteristic of the tag, such as a transmission rate, a transmission power, a tag identification code, a password, or an encryption code, or which shifts the tag between a normal operational mode and a low power operational mode in which its transmitter is disabled.

Abstract: An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits signpost signals (24) that are received by a tag (12, 271-275, 301-316, 395-397, 616-618, 641643, 653, 656-657, 662-664, 679, 708, 711). The tag in turn transmits radio frequency beacon signals (72) which are received by a reader (13, 261, 319, 521-530) The tag can vary the duration of the beacon signals, for example in dependence on whether it is currently receiving a signpost signal. Further, the tag can dynamically vary the transmission rate and/or transmission power of the beacon signals, for example following receipt of a signpost signal. Varying these parameters can facilitate compliance with governmental regulations.

Abstract: A wireless communication system with one or more remote transceivers for transmitting a wireless data signal at an actual frequency that is different than the expected frequency and a base transceiver that can automatically adjust to receive the actual frequency. Each remote transceiver is adapted to initiate a wireless data signal at a selected time that is unique to that remote transceiver. The expected frequency is sequentially pre-determined in a pseudo-random sequence with each remote transceiver having a unique sequence. The base transceiver can respond to the remote transceiver at the actual frequency. Both the remote transceiver and the base transceiver can convert the wireless signals in a single step to baseband.

Abstract: A wireless communication system with one or more remote transceivers for transmitting a wireless data signal at an actual frequency that is different than the expected frequency and a base transceiver that can automatically adjust to receive the actual frequency. Each remote transceiver is adapted to initiate a wireless data signal at a selected time that is unique to that remote transceiver. The expected frequency is sequentially pre-determined in a pseudo-random sequence with each remote transceiver having a unique sequence. The base transceiver can respond to the remote transceiver at the actual frequency. Both the remote transceiver and the base transceiver can convert the wireless signals in a single step to baseband.