Study On Narrow-Directivity Of Fiber-Optic Vector Hydrophone

Vector hydrophone draws more attention of researchers in the field of water acoustic and other correlative domain by its fine performance day by day. Fiber-optical vector hydrophone has the high performance which a series of other type vector sensor doesn't have, like piezoelectricities. This point has already been proved in the comparison of the fiber-optical hydrophone and the piezoelectricity hydrophone. This article elaborated the working principle of fiber-optical vector hydrophone system. The optics structure system and the key technologies of signal demodulation were analyzed and presented in this paper, and had carried on directivity simulation experiment and demarcation experiment were operated on fiber-optical vector hydrophone. Directivity is one of the most basic characteristics in sound navigation and ranging system, which is the main parameter of water acoustic detection system in noise and disturbance elimination. On the basis of correlation characteristic of sound pressure and oscillation velocity in the vector sound field, this article introduced the vector hydrophone of directivity , like the word 8, namely the dipole directivity ,also, who has the certain ability of estimating target bearing, But its main lobe width is approximately 90°, only by being peaked with some certain wave beam can the single vector hydrophone distinguish the multi-goals and accurately locate the goal in practical application. On the basis of peaking technology in existing literature, this article proposed the peaked directivity technology based on the minimal variance non-distortion response, and has a detailed discussion about its peaked mechanism. It can be applied to the target bearing estimation. Simulant and experimental results had proven that the beam width can be suppressed within 20°in this way, and the fiber-optical vector hydrophone combination directivity can be peaked enormously, which has built the foundation for optical fiber vector hydrophone nearray application in the future. Finally, data acquired in lake experiment and the first marine experiment using optical fiber vector hydrophone in 2003 were processed. The azimuth angle of target boat was estimated accurately. The vector sound field signal and noise model coherent characteristic presented in this paper were confirmed in some extent. The performance of optical fiber vector hydrophone and its coherent technique in the bad marine environment was tested.