PURPOSE: To identify and extract only a signal pulse when a continuous noise such as mechanical vibration or an impulsive wave noise such as an AE wave is mixed in the signal pulse.
CONSTITUTION: Inter-shell communication is performed by arranging a transmitter 1 and a receiver 2 at confronting positions via an inner shell A, receiving an ultrasonic pulse of precribed period in which a command signal transmitted from the transmitter 1 is made into a code time series by the receiver 2, and demodulating the command signal. At this time, a signal pulse extraction means C which extracts only the signal pulse from the noise by judging that no other wave receiving signal exists between receiving waves at prescribed interval where the signal pulse is propagated reciprocally in inner shell plate thickness and that signal strength received repeatedly shows appropriate attenuation is provided to extract only a signal wave from the noise mixed in the signal wave. Therefore, it is possible to eliminate a various kinds of ultrasonic noises mixed in the inner shell A and to provide communication with high reliability in which only the signal pulse can be extracted and recognition error for a communication signal can be prevented from occurring.
SUZUKI AKIO
BUTANI MASAAKI
