To exactly transmit vibration detection data to a distant place even when a vibration detecting cable is installed long by mutually connecting the vibration detecting cables through a repeater circuit for each block and performing data processing to signals inputted from the vibration detecting cables at the respective repeater circuits.
Vibration detecting cables 3 are arranged while being mutually serially connected through repeater circuits 4 installed for each block. When a signal is inputted from the vibration detecting cable 3 in the 1st block, a discrimination circuit 11 inside the repeater circuit 4 observes the waveform of signal from the vibration detecting cable 3 in the 1st block so as to discriminate whether this signal is inputted by any invading action or simply by wind. In this case, the repeater circuit 4 changes the transmission style of data for specifying the block of invading action so as to transmit these data.
KOSHIBA YOSHIHITO
KINOSHITA MASAHIRO
