Papers by Keyword: Vector Hydrophone

Abstract: The method of Multiple Stress Concentration Regions (MSCRs) on the surface of MEMS Silicon micro-structure is introduced in order to enhance the sensibility of the hair vector hydrophone without reducing the working bandwidth. The MSCRs with the thickness and width smaller than the rest of the cantilever can produce localized stress concentration when constant force is applied on the structure. ANSYS software has been used as a tool to analyze the effect of different shapes and dimensions on the performance of the micro-structure. The optimum MSCR has been obtained. Results show that compared with the ordinary structure, the sensitivity of the micro-structure with MSCR can be increased by 1.5 times, and the upper limit of bandwidth can be improved from 337Hz to 500Hz. This paper provides a new method to resolve contradiction between the sensitivity and working bandwidth.

Abstract: Representation model of composition event is a very important issue in the study of composition event. Aiming to solve the problem of no well reflecting the spatial-temporal characteristic of CPS (Cyber-Physical Systems) in current composition even models, a representation model of composition event based on multi-tuple is proposed for CPS in this paper. The contribution of the paper lies that we use five tuples: object, time, space, event and property, to represent a composition event of CPS, which not only can more comprehensively reflect the spatial-temporal characteristic of CPS event, but also can reflect the some dynamic change features of external environment. The simulation results show that our proposed scheme has several advantages in reducing event average error rate compared with some general event model methods.

Abstract: This paper introduced a underwater acoustic signal acquisition module which used preamplifier, filter plate and the digital circuit board collect original data for 20 Hz to 1K Hz frequency data through acoustic vector hydrophone .It could send the collected data to the PC on the coast through wireless data transmission radio station and store the collected original data d into the SD card as well.

Abstract: As a useful tool for line spectrum detection in underwater signal ,ALE has been used wildly. But there are still some problems to influence the effect of ALE. This paper gives three problems on ALE and analyses these.Then by the characteristics of vector hydrophone and a improved variable step size LMS,this paper constructs a cascade double input with variable step size based on vector hydrophone line spectrum enhancer . This algorithm restrains the noise of main channel twice ,meanwhile controls the noise in reference channel , so as to improve signal to noise ratio better. At the same time ,because of adopting the improved variable step size LMS, the steady-state error is reduced. From the results of simulation and experiment, the method presented in this paper can have a better effect of line spectrum enhancement.

Abstract: This paper realizes 1.2kbps Mixed Excitation Linear Prediction (MELP) speech compression algorithm through multi-frame joint and Vector Quantization technology. In order to adapt to underwater acoustic channel, we apply the Orthogonal Frequency Division Modulation (OFDM) to modulate the source bits, together with synchronization, channel estimation and RS error correcting code technology. The hardware platform of this system relies on TMS320DM642 and AIC23. Moreover, we introduce single vector hydrophone to restrain the local source. The system finished duplex speech signal acquisition and transmission and tank test results prove that the synthesized speech is clear and understandable and it has a stable performance.

Abstract: To apply vector hydrophone to deep-sea detection, a calibration test of the vector hydrophone under different hydrostatic pressure was taken in the national defence underwater acoustics calibration laboratory. The effect of the relative sensitivity changes between channels on the vector hydrophones direction finding and zero-inhibition performance is explored, and the principle model for the influence of the directivity deviation on vector direction measuring is established. Meantime, the phase compensation between channels is found to be frequency-independent. The omnidirectional method is proposed to compensate the directional rotation. As a result, the influences of the hydrostatic pressure on direction finding are effectively reduced.

Abstract: This paper presents a novel micro-electromechanical system (MEMS) piezoelectric vector hydrophone based on ZnO thin film. The approximate theory analysis is introduced in sensitivity and resonant frequency, and a simulation on the vector hydrophone is carried out by finite element method (FEM). Results of the theory analysis and FEM simulation agree well. The results show that the ratio of the piezoelectric layer thickness and Si layer thickness exists an optimum value for sensitivity, and MEMS piezoelectric vector hydrophones in smaller size have higher sensitivity than piezoresistive ones and are of passivity.

Abstract: In the traditional vector data expressions, the outputs of a single 3D vector hydrophone are reorganized into a complex vector, which cannot retain the orthogonality of the velocity elements. In this paper, biquaternion formalism is used to model the vector hydrophone’s output and a novel MUSIC-like algorithm is proposed to estimate the DOA (Direction-Of-Arrival) of the sources. The three velocity channels outputs are placed in the imaginary parts of the biquaternion numbers, which retains the orthogonality of the particle velocities and is robust to correlated/coherent noises. What’s more, the biquaternion data model has a compact way of handing multi-component data, which results a much less memory requirements compared with the traditional approach.

Abstract: The basic array error correction method based on a single auxiliary vector hydrophone is proposed for the difficult problem of the basic array error correction and the constraint of the space size of the tank. This method used the single vector hydrophone by precisely correction to implement non-fuzzy joint estimation of the source orientation and the orientation dependence of the basic array amplitude-phase error, and correct the error of the array element location. The method of this paper is applied to the arbitrary array structure, which doesn't exist the local convergence problem of the joint parameter estimation, only needs one-dimensional search for parameters which make the computing time less and can complete online in real-time.At last, the computer simulation verified the effectiveness of this method.

Abstract: At present the cross-correlation processing can only suppress the isotropic noise by vector hydrophone sound pressure and vibration velocity combined. The coherent composition of the actual ambient noise makes the detection ability of cross-correlation spectrum reduced. Use XWVD theory, proposed a cross symmetry-correlation function (Cross-SCF). Analysis of simulation data under different SNR and Different nature noise combination proving that the noise suppression Performance of suggested Cross-SCF has nothing to do with noise properties, and compared with the cross-correlation processing have indeed better than coherent noise suppression ability.