| 摘要 |
Operating state such as degradation in sensitivity of an AE sensor under use state can be checked. The AE sensor comprises an AE conversion element (41), a pulse signal transmitter (42) for applying a pulse signal to the AE conversion element through the output passage of an AE signal from the AE conversion element (41), a receiver/processor (43) for calculating the frequency characteristics by converting the AE signal into a digital signal and processing the digital signal, a section (44) for storing the frequency characteristics of the AE signal from the AE conversion element under reference state as reference frequency characteristics, and a comparator (45) for comparing the frequency characteristics of the AE signal calculated depending on an operation check request signal with the reference frequency characteristics.
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