JPH0364831B

PURPOSE:To reduce the times of operations and shorten operation time by taking out only the reflected echoes included in a received signal and executing only the computations effective for image formation. CONSTITUTION:The received signal 13 from an object to be examined is stored in a waveform storage part 5, and at the same time, the signal 81 of the position (xr) of a probe 1 is fed to a distance operating part 7. The received signal inputted to the storage 5 is transferred to a waveform preprocessing part 6, by which only the reflected echoes are taken out. The delay time data 51 from the transmission of ultrasonic waves till the reception of the reflected echoes is fed to the part 7, by which the distances between the probe 1 and the position (xr) as well as a defect 22 are calculated and the addresses 71, 72 of an image memory 9 are calculated. Next, the old image data 91 stored in the memory 9 is read out and is transferred to an operator 10. In this operating part, the image data 52 by the sampling of this time is added to the old image data 91, and is written as new image data 92 into the assigned address of the memory 9. In this way, the part 6 is provided to operate only the effective data out of the received signal, and therefore the times of operations are reduced considerably.