Abstract: An underwater sounding apparatus includes a transmitter section (3) for transmitting an acoustic signal in a specific direction underwater from a ship, a receiver section (4) for receiving an echo reflected from inside a fish school FS as a result of the aforementioned transmitted acoustic signal by means of a receiving beam, and a signal processing section (5) for processing signals picked up by the aforementioned receiving beam. The signal processing section (5) calculates fish quantity information about the aforementioned fish school FS by integrating equivalent input sound intensities obtained by the aforementioned receiving beam in specific three-dimensional directions.

Abstract: An underwater sounding apparatus includes a transmitter section (3) for transmitting an acoustic signal in a specific direction underwater from a ship, a receiver section (4) for receiving an echo reflected from inside a fish school FS as a result of the aforementioned transmitted acoustic signal by means of a receiving beam, and a signal processing section (5) for processing signals picked up by the aforementioned receiving beam. The signal processing section (5) calculates fish quantity information about the aforementioned fish school FS by integrating equivalent input sound intensities obtained by the aforementioned receiving beam in specific three-dimensional directions.

Abstract: 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.

Abstract: 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.