| 摘要 |
Methods and apparatus for giving audible warning to a user when one or more accompanying person, animal or personal item is physically more than a predetermined distance away from the user, have a master tag and one or more slave tags, wherein said master tag is wirelessly coupled to each one of said slave tags, said master tag and said slave tag being capable of being conveniently carried by a person or being attached to an animal or a personal item. |
