| 摘要 |
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.
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