FIBRE-OPTIC HYDROACOUSTIC ANTENNA FOR IDENTIFICATION OF UNDERWATER TARGETS Russian patent published in 2001 - IPC

FIELD: underwater acoustics, applicable for guarding of frontiers of water areas against invasion of underwater targets. SUBSTANCE: in the known fiber- optic hydroacoustic antenna (FOHA) made in the form of object and supporting optic fibers of the same length optically matched with a coherent light source and a photodetector into an interferometer the object fiber is made in the form of separate pairs of fibrous coils. The distance between the fibrous coils is different. The given pairs of coils form the sensing elements of the FOHA and are positioned at the frontier of the guarded water area. The secondary equipment of the FOHA comprises an amplifier connected to the output of the photodetector and a great number of parallel-connected correlators connected to the amplifier output. The outputs of the correlators are connected to the plan-position indicator. Each correlator is tuned to a time lag equal to the value of the distance between the pairs of the fibrous coils divided by the sound velocity. EFFECT: enhanced accuracy of determination of the coordinates of the trespasser. 2 dwg