| 摘要 |
<p>An antenna (A) is disposed in a vicinity of a route through which a mobile object (pallet) (P), and a fixed tag (T) is disposed at a location where a radio wave can be received from the antenna (A). When receiving a read command from the antenna (A), a mobile tag (M) attached to the mobile object (P) and the fixed tag (T) send back a response signal at a prescribed timing. A signal received from the fixed tag (T) by the antenna (A) is substantially kept constant, and the signal from the fixed tag (T) cannot be read while buried in a signal transmitted from the mobile tag (M) to the antenna (A) while the mobile tag (M) is positioned at a location where communication with the antenna (A) is expected. On the other hand, when the mobile tag (M) is a prescribed distance or more away from the antenna (A), the signal from the mobile tag (M) cannot be read while buried the signal from the fixed tag (T).</p> |
