Abstract: An object detection method and apparatus in which, in order to distinguish only an echo wave which is returned back from an object of interest, such as an underground buried object, from those echo waves returned back from another object of objects, the observation signal is divided (an electromagnetic wave as an echo wave) into portions, and the signal portion is converted into a corresponding frequency region to evaluate that spectral distribution and computes frequency parameter values from the spectrum distribution. The object of interest is detected by comparing the reference data of various fields with the parameters of the object of interest, extracting only an echo wave returned back from the object of interest and displaying a corresponding image.

Abstract: In an ultrasonic inspecting apparatus, propagation time is measured between a transmitting point of an ultrasonic wave from outer circumference of a subject material and a receiving point of the ultrasonic wave at another point on the outer circumference spaced apart from the transmitting point by a predetermined angle, and a predetermined sequence of operations is performed with the measured propagation times and the known constants, thereby internal information concerning the material, including location and shape of a defect existing therein, is provided.