Patent ID: 7193930
Filing Date: 2007-03-20
Classification: G01S,G10K

Abstract:
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.