Burial on land body detection manner and burial on land body detection sonar

摘要

PROBLEM TO BE SOLVED: To solve the problem that two kinds of low-frequency and high-frequency sonars must be operated simultaneously when an object on the face of the seabed and an object under the face of the seabed are detected simultaneously so as to judge whether a target to be detected exists on the seabed or under the seabed and that an apparatus becomes large-sized and complicated. SOLUTION: An echo sounder transducer array is divided into two parts in the vertical direction, a cross-correlation processing operation between obtained received signals is performed, and the lag time which can obtain its peak is recorded in a time-series manner. At the same time, regarding an echo from the face of the seabed, the theoretical lag time which is derived from the altitude of the seabed, a range, the angle of inclination of the echo sounder transducer or the like is calculated and recorded. A point in which the echo level of a received signal exceeds a threshold value is judged to be the target. The difference between both lag times in the point of the target is detected. When its absolute value becomes the threshold value or more, the target is judged to be a target which is buried in the seabed. When the absolute value is within the threshold value, the target is judged to be a target exposed on the face of the seabed.