A new type of optical fiber underwater acoustic sensor (hydrophone) constructed with two fiber Bragg gratings (FBG) and a self-demodulation ethod is presented in this paper. Unlike other FBG sensors which have separate sensing and demodulating elements, this FBG hydrophone has nly a single structure for both sensing and demodulating using a pair of matched FBGs. The cylindrical structure of the...

A Translation Invariance Denoising Algorithm with Wavelet Threshold and its Application on Signal Processing of Laser Interferometer Hydrophone is investigated. The obtained signal of Laser interferometer hydrophone exist a large number of singularity points, and the denoising algorithm of Donoho’s wavelet threshold may produce the Pseudo Gibbs phenomenon on the singularity points. To eliminate...

This paper introduces a new underwater acoustic eigenstructure ESPRIT-based algorithm that yields closed-form direction-of-arrival (DOA) estimates using a single vector hydrophone. A vector hydrophone is composed of two or three spatially co-located but orthogonally oriented velocity hydrophones plus another optional co-located pressure hydrophone. This direction finding algorithm may (under mo...

Prestressed Concrete Cylinder Pipe (PCCP) is a widely used water pipe all over the world. A major cause of PCCP failure is the internal wire break, which will emit acoustic signal. In this paper, a hydrophone-based PCCP real-time monitoring and failure-prediction system was proposed. By applying wavelet energy normalization analysis to signal feature extraction and Support Vector Machine (SVM) ...

In this paper, a novel dual-mass MEMS piezoelectric vector hydrophone is proposed to eliminate the transverse effect and solve problem of directivity offset in traditional single-mass hydrophones. The reason for directional cantilever explained theoretically first time, angle predicted successfully. Both analytical finite element methods are employed analyze hydrophone. results show that has no...

A novel fiber optic hydrophone based on the integration of a dual polarization fiber grating laser and an elastic diaphragm is proposed and experimentally demonstrated. The diaphragm transforms the acoustic pressure into transversal force acting on the laser cavity which changes the fiber birefringence and therefore the beat frequency between the two polarization lines. The proposed hydrophone ...

We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating) under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular...