Patent ID: 7369459

Claim:
A forward-looking sonar comprising: a transducer array formed of a plurality of transducer elements arranged in line, said transducer array being divided into a first sub array and a second sub array; beamformers for forming a first receiving beam with said first sub array and a second receiving beam with said second sub array within a sounding area; a position measurement section for determining the position of a target based on the direction of the target calculated from a phase difference between echoes from the target received by said first and second receiving beams within the sounding area and the distance to the target calculated from time needed for receiving the echoes after transmission; and a synthesizing section for forming a main beam by adding said first and second receiving beams, calculating the center of gravity or a maximal value of echo signal intensities of an echo detected by said main beam along a range direction in each main beam direction, determining the position of the target from the direction of said main beam and the center of gravity or the maximal value of the echo signal intensities, and synthesizing the position of the target thus determined with the position of the target determined by said position section.