| 摘要 |
<p>Tracking of an article through geographic areas using electromagnetic signals, specifically radio frequency (RF) signals. The article contains a tag (119) operating as a transmitter and receiver. Tag-readers (103,104,105) in the defined geographic areas transmit RF signals and in response, the tag (119) transmits RF signals received by the tag-reader. By knowing the areas in which the tag-readers are located, a system tracks the article by monitoring the tag-readers communicating with the tag.</p> |
