JPS61581B

PURPOSE:To achieve the improvement in the accuracy of analysis by providing blind zone circuits between a converter of ultrasonic waves to electric signals and an electric signal analytical apparatus and separating only the AE wave from the AE wave signal and other signals thereby performing analysis. CONSTITUTION:The AE wave from the measuring object 1 is detected with a detector 2 and is converted to an electric signal wave from vibration waves. The AE voltage is then amplified up to the voltage value necessary for analysis via preamplifier 3 and main amplifier part 4. At this time, blind zone circuits 15 and 16 are serially provided between the detector 2 and analysis part 5. Then if positive and negative blind voltages E+, E- are set same as noise voltages in case the noise signals do not flucturate, no noises will be outputted. Even if various kinds of input noise signals are being applied, they may be removed by connecting the blind zone circuits corresponding to the signal components as much as number of noise components in series and subsequently passing the signals therethrough. The simple circuit constitution eliminates the noise signals, makes possible analysis of only the intended signals and enables accuracy to be improved.