Abstract: According to a level of an input signal, first switching means performs control in such a way that only a first feedback resistor or the first and second feedback resistors become feedback resistors connected to amplifying means, and thereby allows the amplifying means to keep linearity without saturating even when the level of the input signal changes. Furthermore, when the input signal has a higher level than a predetermined threshold, a phase compensation capacitor is charged under the control of second switching means for phase compensation of the amplifying means.

Abstract: According to a level of an input signal, first switching means performs control in such a way that only a first feedback resistor or the first and second feedback resistors become feedback resistors connected to amplifying means, and thereby allows the amplifying means to keep linearity without saturating even when the level of the input signal changes. Furthermore, when the input signal has a higher level than a predetermined threshold, a phase compensation capacitor is charged under the control of second switching means for phase compensation of the amplifying means.

Abstract: Method of and apparatus for measuring a space distribution of spacings between point scatterers. An ultrasonic wave is applied to an ultrasonic scattering medium which is an aggregation of point scatterers. Ultrasonic waves, scattered from the medium, are converted into an electric signal. The shape of a power spectrum of the electric signal is determined. A fractal analysis is effected so as to determine a fractal dimension and self-similarity with respect to the power spectrum shape. A spatial distribution of a structural inhomogeneity of the scattering medium is measured in accordance with results of the fractal analysis.