| 摘要 |
PURPOSE:To improve an SN ratio by generating an ultrasonic wave, which varies in oscillation waveform in every oscillation, from a probe through a modulation oscillator, and averaging its reflected wave signal through a synchronous averaging circuit. CONSTITUTION:In one flaw detecting operation, namely, while an ultrasonic probe 1 is nearly at the same position, a modulation oscillator 7 outputs (n) pieces of oscillation signals having different patterns, and the probe 1 oscillates (n) times to generate ultrasonic waves with different oscillation waveforms S1-Sn. Those ultrasonic waves are reflected at a fault 4 and received as fault echoes by the probe 1. The ultrasonic waves from the probe 1 are scattered at the boundary between a bead 3 and a base material and particulates, etc., present near it, and received as noises and pseudo echoes by the probe 1. Then, the reflected wave signals from this probe 1 are sent to a synchronous averaging circuit 11 through an amplifier 9 and an A-D converter 10. The synchronous averaging circuit 11 synchronizes those reflected wave signals in terms of time and adds and averages them to remove noise components except the fault echoes A. |
