| 摘要 |
PROBLEM TO BE SOLVED: To perform radio communication reliably and quickly even if a frequency channel is automatically changed.SOLUTION: A repeater control unit 5 performs time division of a downlink time slot in a frame #1 into a plurality of transmission periods, and controls a radio transmitting unit 3 to transmit a synchronization signal by changing a channel per transmission period. A sensor control unit 15 having changed its channel can receive the synchronization signal by controlling a radio receiving unit 14 to synchronize with timing when the transmission period starts and intermittently receive the synchronization signal. Having received the synchronization signal, each sensor control unit 15 controls a radio transmitting unit 13 to transmit a radio signal including a response message in an uplink time slot Di allocated to itself by a currently selected channel. Therefore, even if each fire sensor 10 automatically changes its channel, the repeater 1 can reliably and quickly perform radio communication with each fire sensor 10. |
