| 摘要 |
PURPOSE:To correct the ultrasonic signals transmitted from plural probes having different characteristics with one preamplifier circuit without changing over the same by using a digital converter and using the output thereof as the AGC voltage of the preamplifier. CONSTITUTION:The ultrasonic wave signal Ea from a probe 1a beaten by a pulse Pa is inputted through a changeover switch 21 and a cable to a preamplifier 3. A D/A output Va is applied to the preamplifier 3 by the D/A data 7 which is beforehand set with a control circuit 4. Said output acts as an AGC voltage to make the output Ea of the probe constant and the output 10 of the preamplifier E0. Said output is transmitted to a signal processing circuit 5, by which a defect is evaluated. A probe 1b beaten by a pulser signal Pb is similarly corrected with a D/A output Vb, and the output Eb of the probe is made E0. The flaw detection is thus accomplished successively up to Pn. The gain corrected voltage is changed over successively with the D/A converter with respect to the respective probes, whereby the individual characteristics of the probes are corrected. |
