| 摘要 |
<p>In a location monitoring system, a plurality of mutually spaced-apart fixed units (Fig. 1) are each capable of transmitting a wireless (e.g. microwave or infra-red) fixed unit signal (FUS), at least one mobile unit (Fig. 2) to be carried by a person is capable of detecting such a fixed-unit signal when in a limited region with respect to the fixed unit transmitting the signal, and a central unit (Fig. 3) receives a location signal (LS) from the or each mobile unit indicating which fixed unit was last detected by that mobile unit.</p> |
