| 摘要 |
PROBLEM TO BE SOLVED: To allow a metering system to cope with changeover from an analog line to an ISDN line without the need for much cost and time without losing outward appearance. SOLUTION: In this metering system, an indoor adaptor 12 is installed indoor, and an outdoor adaptor 13 is installed outdoor, a transmitter 2 and a gas leakage no-voltage alarm unit 7 are connected to the indoor adaptor 12, a gas meter 1 is connected to the outdoor adaptor 13, and the indoor adaptor 12 and the outdoor adaptor 13 are interconnected by a communication line L1. The indoor adaptor 12 is provided with a signal superimposing means 12A that applies amplitude modulation to an alarm signal from the gas leakage no-voltage alarm unit 7 with a high frequency and superimposes the modulated signal on a signal (low frequency pulse signal) from the transmitter 2, and the outdoor adaptor 13 is provided with a demultiplexer.demodulation means 13A that demultiplexes and demodulates the alarm signal from the transmitter 2 and the alarms signal from the alarm unit 7 superimposed by the indoor adaptor 12.
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