Abstract: An underwater detection apparatus is provided. The underwater detection apparatus includes a transmitter, a receiver, and a hardware processor. The transmitter transmits a transmission wave. The receiver obtains a receive signal based on a reflection of the transmission wave. The hardware processor is programmed to at least detect an underwater target object based at least in part on the receive signal, estimate a density index value of objects within a given area in a vicinity of the underwater target object, and calculate a size index value of the underwater target object based at least in part on the density index value and a target object signal intensity representing a maximum intensity of the receive signal corresponding to the underwater target object.

Abstract: An underwater detection apparatus is provided. The underwater detection apparatus includes a transmitter, a receiver, and a hardware processor. The transmitter transmits a transmission wave. The receiver obtains a receive signal based on a reflection of the transmission wave. The hardware processor is programmed to at least detect an underwater target object based at least in part on the receive signal, estimate a density index value of objects within a given area in a vicinity of the underwater target object, and calculate a size index value of the underwater target object based at least in part on the density index value and a target object signal intensity representing a maximum intensity of the receive signal corresponding to the underwater target object.

Abstract: In a cylindrical transducer constructed of a plurality of ultrasonic transducer arrays arranged in a circular form, the ultrasonic transducer arrays is divided into a plurality of groups, and tilt angles of transmitting and receiving beams are controlled to compensate for swing motions of the cylindrical transducer depending on which group the individual ultrasonic transducer arrays belong. Provided that the uncompensated tilt angle of the beam is a and the angle of inclination of the cylindrical transducer in a particular direction is b, the tilt angle of the beam formed by a transducer array in the inclining direction should be adjusted to &agr;−&bgr; and the tilt angle of the beam formed by a transducer array in the opposite direction should be adjusted to &agr;+&bgr;.

Abstract: In a cylindrical transducer constructed of a plurality of ultrasonic transducer arrays arranged in a circular form, the ultrasonic transducer arrays is divided into a plurality of groups, and tilt angles of transmitting and receiving beams are controlled to compensate for swing motions of the cylindrical transducer depending on which group the individual ultrasonic transducer arrays belong. Provided that the uncompensated tilt angle of the beam is a and the angle of inclination of the cylindrical transducer in a particular direction is b, the tilt angle of the beam formed by a transducer array in the inclining direction should be adjusted to &agr;−&bgr; and the tilt angle of the beam formed by a transducer array in the opposite direction should be adjusted to &agr;+&bgr;.