PURPOSE: To prevent an erroneous component from being inputted by extracting only the part where sound fields of all frequencies formed by a transmitted signal overlap on a reception side.
CONSTITUTION: A transmission part Tr drives a transmitting transducer Ts by a signal which has two center frequencies. At the same time, flip-flop FFa and FFb are set and gate parts Ga and Gb are opened. A transmitted ultrasonic wave is attenuated by respective members in a medium UN and reflected, scattered or transmitted at a boundary surface to reach a receiving transducer TR. The received signal is amplified and supplied to filters FLa and FLb to extract signal components of bands of frequencies fa and fb to be utilized, and they are supplied to a reception processing part Rc, which supplies the received signals to a processing part through gate parts Ga and Gb. Then, the flip-flops FFa and FFb are reset a predetermined time later and the gate parts Ga and Gb are closed. This timing is the time when the signal of each utilized frequency arrives.
HAYASHI OSAMU
SHIMURA NOBUKI
IWASHITA NOBUSHI
IIDA ATSUO
| JPS50104959A | 1975-08-19 |