METHOD FOR DETECTION OF UNDERWATER OBJECTS ON SEA BOUND IN SHALLOW SEA Russian patent published in 2000 - IPC

FIELD: detection of underwater objects. SUBSTANCE: hydroacoustic pulses directed to the upper half-space are radiated from a number of points with known coordinated located on the bottom in the bound line, echo signals reflected from the objects are received in the same points, and location of the object is judged by the coordinates of the receiver that has detected the echo signal, pulses are radiated in the adjacent points at different frequencies and in all points simultaneously, echo signals of natural frequency and at least of two other frequencies are received in each point from detectors on each side adjacent in the line, the distance between the adjacent points of reception-radiation are selected to be equal to a double sea depth in the bound line; the time of arrival of echo signals is limited by the time of arrival of pulses reflected from the sea surface at each frequency received in the given point, and the location of the detected object is defined more exactly by the coordinates of the radiator operating at the frequency of the received echo signals. The level of direct hydroacoustic pulses received from the adjacent radiator is watched, and in case of variation of this level the appearance of an object near the bottom is judged. EFFECT: enhanced truth and continuity of monitoring, prevented zone of unsure reception. 2 cl, 3 dwg