Method and apparatus for tracking devices using tags

Abstract

An apparatus (10, 240, 300) includes a signpost (11, 241-256, 322, 612, 623, 626-628, 652, 661, 682, 686, 703) which transmits relatively low frequency signpost signals that contain a signpost code and are fundamentally magnetic, a beacon tag (12, 271-275, 301-316, 395-397, 616-618, 641-643, 653, 656-657, 662-664, 679, 708, 711) which receives the signpost signals and transmits radio frequency signals containing the signpost code (42, 93), and a reader (13, 261, 319, 521-530) which receives the radio frequency signals. One of the signpost and tag is mounted on a moveable item to be tracked, and the other is mounted on a similar item or is stationary. A sensor (32) can be provided to detect the presence of an item and cause the signpost to change its transmitted signpost code. The tag can vary the duration, transmission rate, and / or transmission power of its beacon signals. A control system (14, 500) responsive to the reader can cause the signpost to vary its signpost signal in a manner which causes the tag to shift between normal and low power modes, or which causes the tag to vary at least one operational characteristic, such as transmission rate, transmission power, a transmitted password, or various transmitted codes.

Description

[0001] Copyright Notice [0002] Portions of this patent publication relate to material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of this patent document or this patent publication as it appears in any patent office file or record, but otherwise reserves all copyrights. technical field [0003] The present invention relates generally to techniques for tracking items, and more particularly to techniques for tracking items using wireless tags. Background technique [0004] According to existing item tracking technology, a device called a radio frequency identification tag is installed on each item, and a radio frequency signal is used to transmit information from the tag to a receiver called a reader. Tags can be active or passive. While existing tags and systems using them are generally adequate for their respective purposes, they are not satisfactory in all respects. [0005] In this regard, there...

AI Technical Summary

Problems solved by technology

[0009] Another shortcoming of the prior art is that some existing tags can transmit in response to an interrogation signal, but, otherwise, pre-existing tags generally function in a predetermined manner independent of outside influence

Therefore, there is no convenient way to easily change some of the operational characteristics of a tag other than replacing a given tag

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