Furuno Electric Company Limited

Takanori Satoh

Yuriko Onishi

Osamu Kubota

Hiroyuki Toda

Shinji Ishihara

Satoshi Misonoo

Mitsuhiro Inouchi

Youhei Kinoshita

Katsuhisa Yamamoto

A sonar emits an ultrasonic wave into the water from a transducer on the basis of a transmission signal outputted from a transmission circuit, receives an echo reflected in the water with the transducer and converts the echo into an electric signal, and displays underwater information on a display unit on the basis of an echo signal extracted by processing the electric signal. A tailing signal removing unit for removing a tailing signal and extracting only the echo signal is provided in the sonar such that a video of a surface layer fish shoal is clearly displayed on a screen of the display unit without being hidden by a video of the tailing signal.

Sonar

A quantitative echo sounder includes delay circuits, phase correction circuits, an incidence angle calculator and a directivity correction unit. The delay circuits adjust transmission start timing or phases of acoustic waves radiated by individual vibrating elements based on pitch and roll angles measured by a motion sensing device so that the direction of an acoustic axis of a transmitting beam matches a sounding direction. The phase correction circuits adjust phases of received echo signals based on the pitch and roll angles so that the direction of an acoustic axis of a receiving beam matches the sounding direction. The incidence angle calculator calculates echo signal incidence angle with respect to the sounding direction from phase differences among receiving beam signals obtained by four vibrating element groups. The directivity correction unit corrects a measured target strength by using the echo signal incidence angle calculated by the incidence angle calculator.

Quantitative echo sounder and method of quantitative sounding of fish

Growing community of inventors

Nishinomiya, Japan

Takanori Satoh