| 摘要 |
PURPOSE: To compensate the ultrasonic damping frequency characteristic of a specimen, reduce the side lobes near a main lobe and the side lobes at the periphery section, improve the S-N ratio of the received echo, and improve the defect measurement resolution in the ultrasonic flaw detection method using the pulse compression technique. CONSTITUTION: The ultrasonic wave by the chirp wave with the prescribed pulse width is transmitted from an FM signal transmission section 3 to a specimen 5 via a probe 4, and compression treatment is applied to the received signal by a pulse compression process section 6 with the reference signal from a reference wave set section 7 for the flaw detection of the specimen 5 in this ultrasonic flow detection method. The amplitude attenuation factor for each frequency component of the pulse-compressed signal against the amplitude of the transmitted pulse is obtained from the ultrasonic damping frequency characteristic of the specimen 5 in advance, and the amplitude for each frequency component of one or both of the transmitted pulse signal and the reference signal is set to supplement the obtained amplitude attenuation factor for each frequency component. |
