| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that a security device cannot operate due to deterioration of an electric wave environment. SOLUTION: A radio slave unit 3 starts receiving a radio signal from a radio master unit 4 in the timing of periodic communication. A determination means 6 determines whether or not a radio signal can be received from the radio master unit 4. When it is determined that the radio signal can be received, the same processing is repeated in the following timings of the next periodic communication. On the other hand, when it is determined that the radio signal of the periodical communication cannot be received, a valve shut-off signal is transmitted from the radio slave unit 3 to the gas meter 1, and a gas channel is shut-off by a shut-off valve 2. COPYRIGHT: (C)2011,JPO&INPIT
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