Quantitative echo souner and method of quantitative sounding of fish
First Claim
1. A split-beam type quantitative echo sounder having a capability to correct a measured target strength of an object by the angle of incidence of echo signals returned by said object, said quantitative echo sounder comprising:
- a transducer having a plurality of vibrating elements for radiating acoustic waves, the vibrating elements being arranged close to one another on a flat plane and divided at least into three groups, the centers of gravity of the three vibrating element groups being located not in line;
a transmit signal regulator for matching the direction of an acoustic axis of a transmitting beam with a predetermined sounding direction by adjusting transmission start timing or phases of the acoustic waves radiated by the individual vibrating elements based on pitch and roll angles measured at a moment of transmission start and the positions of the individual vibrating elements on the transducer;
a received signal regulator for matching the direction of an acoustic axis of a receiving beam with said sounding direction by adjusting phases of the echo signals received by the individual vibrating elements based on pitch and roll angles measured at a moment of receiving the echo signals and the positions of the individual vibrating elements on the transducer;
an incidence angle calculator for calculating the angle of incidence of the echo signals with respect to said sounding direction from phase differences between receiving beam signals formed from the phase-adjusted received echo signals obtained by at least one vibrating element group; and
a first target strength corrector for correcting the measured target strength of said object based on the calculated incidence angle of the received echo signals.
1 Assignment
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Accused Products
Abstract
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.
19 Citations
9 Claims
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1. A split-beam type quantitative echo sounder having a capability to correct a measured target strength of an object by the angle of incidence of echo signals returned by said object, said quantitative echo sounder comprising:
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a transducer having a plurality of vibrating elements for radiating acoustic waves, the vibrating elements being arranged close to one another on a flat plane and divided at least into three groups, the centers of gravity of the three vibrating element groups being located not in line;
a transmit signal regulator for matching the direction of an acoustic axis of a transmitting beam with a predetermined sounding direction by adjusting transmission start timing or phases of the acoustic waves radiated by the individual vibrating elements based on pitch and roll angles measured at a moment of transmission start and the positions of the individual vibrating elements on the transducer;
a received signal regulator for matching the direction of an acoustic axis of a receiving beam with said sounding direction by adjusting phases of the echo signals received by the individual vibrating elements based on pitch and roll angles measured at a moment of receiving the echo signals and the positions of the individual vibrating elements on the transducer;
an incidence angle calculator for calculating the angle of incidence of the echo signals with respect to said sounding direction from phase differences between receiving beam signals formed from the phase-adjusted received echo signals obtained by at least one vibrating element group; and
a first target strength corrector for correcting the measured target strength of said object based on the calculated incidence angle of the received echo signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of split-beam type quantitative fish echo sounding by use of a transducer having a plurality of vibrating elements for radiating acoustic waves, the vibrating elements being arranged close to one another on a flat plane and divided at least into three groups, the centers of gravity of the three vibrating element groups being located not in line, in which a measured target strength of an object is corrected by the angle of incidence of echo signals returned by said object, said method comprising:
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matching the direction of an acoustic axis of a transmitting beam with a predetermined sounding direction by adjusting transmission start timing or phases of the acoustic waves radiated by the individual vibrating elements based on pitch and roll angles measured at a moment of transmission start and the positions of the individual vibrating elements on the transducer;
matching the direction of an acoustic axis of a receiving beam with said sounding direction by adjusting phases of the echo signals received by the individual vibrating elements based on pitch and roll angles measured at a moment of receiving the echo signals and the positions of the individual vibrating elements on the transducer;
calculating the angle of incidence of the echo signals with respect to said sounding direction from phase differences between receiving beam signals formed from the phase-adjusted received echo signals obtained by at least one vibrating element group; and
correcting the measured target strength of said object based on the calculated incidence angle of the received echo signals.
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9. A split-beam type quantitative echo sounder comprising:
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a transducer having a plurality of vibrating elements for radiating acoustic waves;
a transmit signal regulator for matching the direction of an acoustic axis of a transmitting beam with a predetermined sounding direction based on pitch and roll angles measured at a moment of transmission start; and
a received signal regulator for matching the direction of an acoustic axis of a receiving beam with said sounding direction based on pitch and roll angles measured at a moment of receiving echo signals.
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Specification