Underwater sounding apparatus and method capable of calculating fish school information, volume of fish school and backscattering strength of single fish

摘要

An underwater sounding apparatus includes a transducer transmitting an acoustic sounding beam along a plurality of directional surfaces that intersect in three-dimensions and receiving echoes returning from within a fish school using receiving beams. The transducer can form the receiving beams in directions generally along a substantially vertical planar directional surface and in directions generally along a substantially umbrella-shaped directional surface formed around the ship, the umbrella-shaped directional surface intersecting both a horizontal plane and the vertical, planar directional surface. A signal processing section calculates fish quantity information about the fish school by constructing pseudo-three-dimensional data from data obtained by the receiving beam. Also, the signal processing section may binarize the data obtained by the receiving beams and calculates an approximate value of the volume of the fish school by constructing pseudo-three-dimensional data from the binarized data.