Vector Hydrophone Research Articles

A Bionic Fish Cilia Median-Low Frequency Three-Dimensional Piezoresistive MEMS Vector Hydrophone

AbstractA bionic fish cilia median-low frequency three-dimensional MEMS vector hydrophone is reported in this paper. The piezoresistive reasonable position was obtained through finite element analysis by ANSYS and the structure was formed by MEMS processes including lithography, ion implantation, PECVD and etching, etc. The standing wave barrel results show that the lowest sensitivity of the hydrophone is −200 dB and reach up to −160 dB (in which the voltage amplification factor is 300). It has a good frequency response characteristics in 25 Hz ∼ 1500 Hz band. Directivity tests displayed that the hydrophone has a good “8”-shaped directivity, in which the resolution is not less than 30 dB, and asymmetry of the maximum axial sensitivity value is less than 1.2 dB.

Study on Vector Hydrophone Array DOA Estimation

Vector hydrophone is composed of acoustic pressure sensor and particle velocity sensor, which can simultaneously measure acoustic pressure and orthogonal components of particle velocity. MUSIC (Multiple Signal Classification) algorithm is a high resolution spatial spectrum analysis method based on subspace decomposition. This paper introduces the operation principles of this algorithm in detail and investigates the application of MUSIC algorithm to the DOA estimation of acoustic sources by a vector-hydrophone ULA (Uniform Linear Array) output model. Simulation results indicate that the resolution capability of MUSIC algorithm under larger SNRs is excellent.

USTC-MUSIC Algorithm for DOA Estimation of Coherent Sources Using Single Vector Hydrophone

The MUSIC algorithm cannot deal with the problem of DOA estimation of coherent sources, this paper proposes the USTC (unitary spatio-temporal correlation matrices)-MUSIC algorithm using single vector hydrophone to solve this problem, by utilizing the unitary spatio-temporal correlation matrix instead of the covariance matrix. The simulation results demonstrate that the USTC-MUSIC algorithm has a better ability to distinguish the coherent sources from different directions than the spatial smoothing MUSIC algorithm.

Direction of Arrival Estimation Based on a Tensor Approach

In this letter, we put forward a novel tensor-based Multiple Signal Classification (TB-MUSIC) applicable to a vector hydrophone array. For this purpose, the signal subspace is derived from the higher order singular value decomposition (HOSVD) of the third order tensor of the output model. Then the proposed method is achieved by signal subspace projection weighted with the reciprocal of principal singular values multiplying by the spatial spectrum based on TB-MUSIC. The synthetic spatial spectrum shows higher resolution and robustness under no-ideal scenarios. Monte Carlo experimental results are provided to illustrate the better performance of the proposed method.

Beam-patterns of a collocated unit of three orthogonally oriented second-order directional sensors

A microphone or a hydrophone measures the incident acoustic wavefield as a scalar field of pressure. Underlying this pressure scalar is the particle-velocity vector, which constitutes the spatial gradient of the wavefield. Each Cartesian component of this gradient vector may be directly measured (without computing any spatial derivative) by a particle-velocity sensor aligned in parallel to that Cartesian coordinate. The entire 3 × 1 gradient vector may be measured at any point in space, using three such particle-velocity sensors, collocated but orthogonally oriented among themselves. Such a collocated triad has an array manifold independent of signal frequency, thus uncoupling azimuth-elevation beamforming from the frequency-dimension. This triad’s beam-pattern has already been investigated by Wong and Chi ["Beam patterns of an underwater acoustic vector hydrophone located away from any reflecting boundary,” IEEE J. Ocean. Eng. 27(3), 628–637 (2002)]. While the particle-velocity sensor measures the first-order spatial derivative of the pressure field, a second-order spatial derivative of the pressure-field could likewise be defined and be measured by a “second-order directional sensor” that would have sharper directivity. This paper follows up that investigation, but now for second-order directional sensors.

A Design of Underwater Acoustic Signal Acquisition Module

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.

Decoupled 2D Direction-of-Arrival Estimation using Partly Calibrated Vector Hydrophones

The work presented here applies rank reduction estimator (RARE) to address the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation in a computationally efficient way. Using an array of acoustic vector sensors with inter-vector-sensor nonidealities, the proposed method decouples the azimuth angle estimation from the elevation angle estimation by exploiting the unique array manifold of the acoustic vector sensor, thereby breaking 2D parameter search into two independent one-dimensional (1D) parameter search. To further reduce the computational load, the proposed method uses ESPRIT to self-generate coarse estimates of the sources' arrival angles to start off its RARE-based iterative search.

Research of Vector Hydrophone Adaptive Signal Processing

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.

Calibration of Vector Hydrophones in Deep Water

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.

Implementation and Design of Underwater Duplex Speech Communication System Based on Vector Hydrophone

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.

Design of MEMS Piezoelectric Vector Hydrophone

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.

Blind DOA Estimation Based on Single Acoustic Vector Hydrophone

In this paper a blind direction of arrival (DOA) estimation method based on single acoustic vector hydrophone is presented according to the characteristics of underwater acoustic waves. With no priori assumptions about the structure of steering vector, the vector hydrophone array manifold is estimated by the joint approximate diagonalization of eigen-matrices (JADE) algorithm. Simultaneously, acoustic waves are reconstructed by the separation matrix and signal vector. Finally, with the orthogonality of the components of particle velocity the DOA are estimated. Simulation experiment proves the effectiveness and correctness of this new method.

Time-space transform: A novel signal processing approach for an acoustic vector-sensor

A new signal processing method using a single vector hydrophone is proposed for solving the problem of azimuth angle estimation for multiple targets based on a small aperture underwater platform. The method extends the aperture from a single vector hydrophone into a half wavelength distance uniform linear array by decomposing the time-domain sample data from different channels of the hydrophone. The extended array has a narrower space beam pattern than a single vector hydrophone. The azimuths of spatial multiple targets are estimated by using the appended array snapshots under the condition of broadband or narrow band signals. The new method is robust because there is no need to correct the array manifold. Theoretical analysis and computer simulations show that, the new algorithm has the ability to distinguish two incoherent targets with either narrow band or broadband signals in an isotropic noise field. The algorithm provides a non-biased estimate with a high signal-to-noise ratio.

Study of Pattern Time Delay Coding Underwater Acoustic Communication Technique Based on a Single Vector Hydrophone

Study of Pattern Time Delay Coding Underwater Acoustic Communication Technique Based on a Single Vector Hydrophone

Biquaternion Model of Vector Hydrophone Array and DOA Estimation Algorithm

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.

The Near-Field Correction Method of the Basic Array Error Based on a Single Auxiliary Vector Hydrophone

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.

Suppression of Single Vector Hydrophone Coherent-Noise Based on the Cross-SCF

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.

Self-adapting root-MUSIC algorithm and its real-valued formulation for acoustic vector sensor array

Abstract In this paper, based on the root-MUSIC algorithm for acoustic pressure sensor array, a new self-adapting root-MUSIC algorithm for acoustic vector sensor array is proposed by self-adaptive selecting the lead orientation vector, and its real-valued formulation by Forward-Backward(FB) smoothing and real-valued inverse covariance matrix is also proposed, which can reduce the computational complexity and distinguish the coherent signals. The simulation experiment results show the better performance of two new algorithm with low Signal-to-Noise (SNR) in direction of arrival (DOA) estimation than traditional MUSIC algorithm, and the experiment results using MEMS vector hydrophone array in lake trails show the engineering practicability of two new algorithms.

A Kind of Minitype 2D Vector Hydrophone

A special designed 2D accelerometer was successfully used in the design of the minitype 2D vector hydrophone. The theory, design and experiment test data of both the accelerometer and the vector hydrophone was presented in this paper. The accelerometer based on cantilever beam mode and used PZT tube to substitute the PZT plate which was traditional used, this substitution enhanced the mechanical strength of the accelerometer, which resulted to the high performance of the 2D vector hydrophone in its natural frequency and sensitivity. The outside electrode of the PZT tube was divided into four equivalent parts, and each opposite part was wiring connected into one accelerometer channel, thus the two orthotropic accelerometer channels was integrate into one 2D cantilever beam mode accelerometer. The minitype vector hydrophone was designed based on this compact 2D accelerometer, and it’s high performace makes it possible to be used in under water sonar transducer arrays.

Underwater patch near-field acoustical holography based on particle velocity and vector hydrophone array

One-step patch near-field acoustical holography (PNAH) is a powerful tool for identifying noise sources from the partially known sound pressure field. The acoustical property to be reconstructed on the surface of interest is related to the partially measured pressure on the hologram surface in terms of sampling and bandlimiting matrices, which cost more in computation. A one-step procedure based on measuring of the normal component of the particle velocity is described, including the mathematical formulation. The numerical simulation shows that one-step PNAH based on particle velocity can obtain more accurately reconstructed results and it is also less sensitive to noise than the method based on pressure. These findings are confirmed by an underwater near-field acoustical holography experiment conducted with a vector hydrophone array. The experimental results have illustrated the high performance of one-step PNAH based on particle velocity in the reconstruction of sound field and the advantages of a vector hydrophone array in an underwater near-field measurement.