Quantitative echo sounder and method of quantitative sounding of fish

• Main Authors: TODA HIROYUKI, YAMAMOTO KATSUHISA, KINOSHITA YOUHEI, KUBOTA OSAMU, ONISHI YURIKO, MISONOO SATOSHI, SATOH TAKANORI
• Format: Patent
• Language: English
• Published: 20.03.2007
• Subjects: ACOUSTICS; ACOUSTICS NOT OTHERWISE PROVIDED FOR; ANALOGOUS ARRANGEMENTS USING OTHER WAVES; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; MUSICAL INSTRUMENTS; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; SOUND-PRODUCING DEVICES; TESTING

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.