| 摘要 |
A compact warning device for preventing child from being lost comprises a high frequency distance-adjustable host transceiver and a plurality of slave transceivers wherein the high frequency host transceiver is carried by the parents and a high frequency slave transceiver is secured on a child, and the host and the slave transceivers can proceed bi-directional page or response with its counterpart. When one of the slave transceivers departs from the host transceiver beyond a preset security range, both the host and the slave transceiver will alarm to warn the child and the parents in order to prevent the child from being lost. Moreover, as this invention is capable of adjusting security range in multiple stages, it can fit various circumstantial conditions.
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