Array gain for a conformal acoustic vector sensor array:An experimental study

An acoustic vector sensor can measure the components of particle velocity and the acoustic pressure at the same point simultaneously, which provides a larger array gain against the ambient noise and a higher angular resolution than the omnidirectional pressure sensor. This paper presents an experimental study of array gain for a conformal acoustic vector sensor array in a practical environment. First, the manifold vector is calculated using the real measured data so that the effects of array mismatches can be minimized. Second, an optimal beamformer with a specific spatial response on the basis of the stable directivity of the ambient noise is designed, which can effectively suppress the ambient noise. Experimental results show that this beamformer for the conformal acoustic vector sensor array provides good signal-to- noise ratio enhancement and is more advantageous than the delay-and-sum and minimum variance distortionless response beamformers.

Analysis of SNR for Acoustic Vector Sensor Linear Array in Volume and Surface-generated Noise Fields

Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.

Design of Reduced Graphene Oxide Based Piezo-Resistive Type Acoustic Sensor on Flexible Kapton for Underwater Applications

Micro Electro Mechanical Systems (MEMS) vector sensor is a recent advancement in the field of underwater acoustic sensors. The major incentive provided by this acoustic vector sensor is that it provides information about the direction of the incoming acoustic source signal in addition to the measurement of the pressure associated with the acoustic signal. We are reporting a design of a MEMS acoustic vector sensor for underwater applications using piezoresistive film of Reduced Graphine Oxide (RGO), realized on kapton (polyimide) film as the starting material. The sensor is designed and fabricated by deposition of RGO on a kapton, which is a flexible substrate by the method of drop casting making the process simple, low-cost and scalable. The application of the piezoresistive transduction principle and ingenious structure of the vector sensor based on bionic principle improves miniaturization and the low-frequency sensitivity. The fabricated sensor shows a repeatable response in both static and dynamic conditions, to the applied strain due to the acoustic signal in a given direction. The experimental results show that fabricated sensor based on MEMS technology and piezoresistive effect is feasible and it possesses intrinsic two-dimensional directivity. The fabricated device has given good response for the low-frequency acoustic signals due to the effect of piezoresistive transduction principle and the resonance frequency of the device is found to be around 80 Hz with the displacement sensitivity around 3 mV/mm and 2 mV/mm of X and Y axis directions respectively.

基于AVS和稀疏表示的鲁棒语者声源DOA估计方法

基于声学矢量传感器（Acoustic vector sensor,AVS）和空间声源稀疏表示理论,进行了鲁棒的高精度语者声源到达角（Direction of arrival,DOA）估计方法研究。考虑混响和加性噪声影响,本文推导了AVS接收信号的向量化的协方差矩阵模型,设计了过完备字典,依此建立声源的空间稀疏表示模型,最终通过求解稀疏空间谱获得鲁棒的DOA估计。本文进行了大量的不同混响和加性噪声条件下的仿真实验和实际环境中的DOA估计实验,实验结果表明,本文提出的语者声源DOA估计方法在信噪比5-30dB范围内可获得均方根误差（Root mean square error,RMSE）小于1°的估计精度。在实际环境中也取得了2-10°误差的DOA估计结果。

Fast direction of arrival algorithm based on vector-sensor arrays using wideband sources

An acoustic vector sensor(AVS)can capture more information than a conventional acoustic pressure sensor(APS).As a result,more output channels are required when multiple AVS are formed into arrays,making processing the data stream computationally intense.This paper proposes a new algorithm based on the propagator method for wideband coherent sources that eliminates eigen-decomposition in order to reduce the computational burden.Data from simulations and lake trials showed that the new algorithm is valid:it resolves coherent sources,breaks left/right ambiguity,and allows inter element spacing to exceed a half-wavelength.

定向接收低冲突率水声网络媒体接入控制协议

在全向水声通信网络场景中,较大的传播时延和较高的数据包碰撞率严重影响了网络性能。相比全向接收技术,声矢量传感器的声压和振速通过线性加权组合可以形成单边指向性,实现定向接收某个方向上的信号,进而提高网络的空间复用率。该文首先分析了声矢量传感器定向接收模式下的网络中断概率,验证定向接收技术网络应用的可行性。然后,提出了定向接收低冲突概率媒体接入控制协议(DRLCP-MAC)。该协议利用指向性接收波束握手机制建立稳定的数据传输链路,通过状态转移策略构建多对并行通信链路,缩小虚拟载波监听范围,提高网络的空间复用度。仿真结果表明,与水下冲突避免多址接入协议(MACA-U)和时隙地面多址接入协议(Slotted-FAMA)相比,DRLCP-MAC协议使信道接入成本降低了约50%和60%,网络吞吐量提升了约60%和400%,端到端时延降低了约50%和85%。

模型误差条件下声矢量圆阵多重信号分类测向改进算法

针对非正规协方差矩阵引起声矢量圆阵多重信号分类(MUSIC)测向算法性能恶化的问题,提出了一种基于奇异值分解的声压振速联合处理MUSIC改进算法。理论分析了阵列响应误差和噪声模型误差对协方差矩阵的正规性及估计性能的影响。模型误差条件下声矢量阵声压振速联合处理的协方差矩阵不再是正规矩阵,改进的MUSIC方法通过对声压振速联合处理的协方差矩阵进行奇异值分解,利用非正规矩阵的左、右奇异向量自身正交的特性,采用奇异向量张成噪声子空间。数值仿真结果表明,改进的MUSIC方法改善了波达方向估计精度和多目标分辨能力,且具有更低、更平坦的空间背景谱。湖上试验进一步验证了改进的MUSIC方法的有效性。

主特征向量加权的声矢量圆阵波束域多重信号分类测向方法

为降低声矢量圆阵方位估计方法的计算复杂度,避免声压振速联合处理需选取观测方向的问题,提出了一种主特征向量加权的声矢量圆阵波束域多重信号分类(MUSIC)测向方法。在信号总功率与噪声功率之比最大的优化准则下,求解得到单矢量传感器最优的加权向量,即主特征向量。结合主特征向量设计相应的波束形成矩阵,并从理论上对声矢量圆阵阵元域和波束域MUSIC的目标方位估计方差进行比较。推导了单矢量传感器的大特征值和信号功率、大特征值对应的特征向量和其导向向量之间的关系。通过仿真实验验证了基于主特征向量波束形成矩阵的有效性,所提方法具有较低的计算复杂度和良好的方位估计性能。水池实验数据分析表明,所提方法能够准确估计目标方位。

矢量传声器多基融合定位

矢量传声器在目标声源方位(Direction of Arrival,DOA)估计方面具有天然的优势性能。在单矢量传声器实现目标声源DOA估计的基础上,利用交叉定位的思想推导多矢量传声器融合实现目标定位的模型,并给出模型的总体最小二乘解。针对奇异方位角影响估计精度的问题,利用圆概率偏差确定有效方位角后再进行融合定位。仿真分析与定位验证实验的结果表明,该方法可以实现目标声源位置估计,在消声室环境下具有较好的定位精度,有效性和实用性较强。

深海环境下利用单矢量传感器估计目标深度

针对深海环境下目标的深度估计问题,本文研究了可靠声路径下直达波和表面反射波形成的周期性干涉调制模式。提出了一种利用单矢量传感器结合周期干涉调制结构对目标深度估计方法。依据矢量传感器接收到的声场信号构建周期干涉调制结构,利用水平复声强和垂直复声强获得目标的垂直到达角,通过周期干涉调制结构同目标深度之间的关系估计目标的深度。Bellhop数值仿真实验结果表明该方法能够有效估计目标深度,并且不需要精确的海洋环境知识。

水下无线传感器网络自适应锥体矢量路由协议

水声传感器网络(Underwater Acoustic Wireless Sensor Networks,UWSNs)由于复杂的水下环境,面临着投递率低、传播延迟高和节点能耗大等挑战。为解决这些问题,文章提出了一种自适应锥体矢量路由协议(Adaptive Cone Vector Routing Protocol,ACVRP),根据节点密度自适应调整锥体区域大小和方向,减少冗余通信和网络能耗,并根据节点的剩余能量和节点在锥体区域中的位置确定节点转发优先级,以提高投递率、减少传输跳数。仿真实验结果显示,与VBF、AHH-VBF和AHHC-VBF相比,ACVRP在包投递率、能效和端到端延迟方面均表现更佳。

用于甚低频水声信号检测的电化学敏感单元设计

针对深海环境下对72 Hz以下甚低频水声信号的感知和探测需求,该文研制一种基于电化学换能原理和MEMS技术的电化学敏感单元。该电化学敏感单元包括MEMS敏感电极、有机玻璃制作的电化学反应腔、胶膜和电解质溶液等。采用MEMS技术和Pt-Pt倒装键合技术在单晶硅衬底上完成MEMS敏感电极的加工和制作,采用螺纹紧固的方法完成电化学敏感单元的装配。最后,将电化学敏感单元通过声学灌封制备得到电化学矢量水声传感器样机,并随电化学矢量传感器样机进行测试,测试结果表明,这种电化学敏感单元可用于对72 Hz以下甚低频水声信号的检测。

Direction-of-arrival estimation for a uniform circular acoustic vector-sensor array mounted around a cylindrical baffle

This work investigates the direction-of-arrival(DOA) estimation for a uniform circular acoustic Vector-Sensor Array(UCAVSA) mounted around a cylindrical baffle.The total pressure field and the total particle velocity field near the surface of the cylindrical baffle are analyzed theoretically by applying the method of spatial Fourier transform.Then the so-called modal vector-sensor array signal processing algorithm,which is based on the decomposed wavefield representations,for the UCAVSA mounted around the cylindrical baffle is proposed.Simulation and experimental results show that the UCAVSA mounted around the cylindrical baffle has distinct advantages over the same manifold of traditional uniform circular pressure-sensor array(UCPSA).It is pointed out that the acoustic Vector-Sensor(AVS) could be used under the condition of the cylindrical baffle and that the UCAVSA mounted around the cylindrical baffle could also combine the anti-noise performance of the AVS with spatial resolution performance of array system by means of modal vector-sensor array signal processing algorithms.

A subspace fitting algorithm of acoustic vector sensor array and corresponding matrix pre-filter design

In order to ease the pass-band response distortion of the matrix pre-filter,a simple approach for designing matrix spatial filter is proposed,which minimizes the sum of the k maximal distortion norm（k is the number of the constraint points）within the pass-band,while constraining the filter response within the stop-band.Considering the costly amount of calculation of the high-resolution methods,an algorithm with small amount of calculation based on matrix pre-filtering and subspace fitting using acoustic vector array（MF-VSSF）is proposed.Through joint processing of signal subspace of both pressure and particle velocity,the pre-filtering matrix and the signal subspace is decreased to M-dimensional（M is the number of array-element）,hence reduces the time-consumption of the matrix pre-filter design and DOA searching.Simulation results show that,the method offers the same performance as MUSIC with pre-filtering,but has much lesser amount of calculation.Moreover,the designed prefilter can efficiently suppress the interference in the stop-band and improve the estimation and resolution performance of successive DOA estimators.

水声传感器网络MAC协议UW-CSMA/CA的NAV优化

水声传感器网络UW-CSMA/CA协议依据源节点与目的节点间最大传播延时确定NAV,这将导致发生网络延时冗余问题,从而降低网络吞吐量。基于此协议,提出了一种根据节点实际距离计算NAV的AN-MAC协议。该协议根据节点间的实际传输距离计算出传播延时并存储在控制帧中,将节点间实际传播延时替换最大延时来计算NAV,可以有效减少网络冗余延时。为了提高仿真结果的有效性,在NS-Miracle仿真器中将Bellhop和世界海洋仿真系统WOSS相结合,对2种协议进行仿真和比较。结果表明,AN-MAC协议较UW-CSMA/CA协议在吞吐量和传输延时方面均有改善。

Influences on the Spatial Directivity of Acoustic Vector Sensor by Finite Cylinder Baffle and Future Prospects About Eliminating the Effects

The directivity of acoustic vector sensor can be distorted by the sound diffraction wave of baffle.According to Helmholtz integral equation,the directivity of acoustic vector sensor under the condition of finite cylinder baffle is calculated by using boundary element method(BEM).Considering the problem of nearly singular integrals of BEM,the exponent parts of fundamental solutions are expanded in trigonometric functions.The singular and the nonsingular parts are separated:the nonsingular parts are calculated by Gaussian integral method;the singular parts are regularized by subsection integral method.Then the surface integrals are reduced into line integrals along the elements' contour which can be calculated by Gaussian integral method.The sound diffraction field of a plane wave under the condition of finite cylinder baffle at different frequencies and incident angles is calculated,and the characteristics of directivity of pressure and vibration velocity at different frequencies are analyzed.The experimental data are treated and the errors between the experimental and theoretical results are analyzed.Finally,according to the research results about the influences on the directivity of acoustic vector sensor by baffle at present,some future prospects about eliminating the effects of sound diffraction field by baffle are presented.

二维声矢量传感器阵列信号波达角估计

将最小冗余线阵结构从一维扩展至二维得到二维冗余阵列,同时各阵元使用声矢量传感器,从而形成二维声矢量传感器阵列。然后利用张量运算对该阵列信号的协方差进行处理得到一个虚拟的声矢量传感器均匀面阵,且虚拟阵元数远多于原物理阵元数即虚拟阵列具有高自由度。最后利用张量分解从虚拟阵列信号数据张量中估计出信号波达角。理论分析和仿真实验结果表明,新阵列及其处理方法具有更高的自由度、更优的信号波达角估计性能。

非均匀噪声下基于稀疏重构的声矢量传感器阵列方位估计方法

为解决非均匀噪声情况下声矢量传感器阵列方位估计性能恶化的问题。提出基于加权最小二乘(weighted least squares,WLS)的稀疏信号重构法和基于加权协方差矩阵拟合(weighted covariance matrix fitting,WCMF)的稀疏信号重构法。定义一个虚拟的声矢量传感器阵列流形矩阵,并重构包含稀疏信号功率和噪声功率的协方差矩阵。为估计稀疏信号功率和每个通道输出的噪声功率,基于WLS法和稀疏信号加权最小化法,构造了关于稀疏信号功率和噪声功率的代价函数。在此基础上,为了进一步提高稀疏信号功率和噪声功率的估计精度,基于WCMF准则对构造的代价函数进行改进。应用泰勒级数展开式将关于稀疏信号功率和噪声功率的非线性代价函数转化为线性函数,并采用循环迭代算法估计稀疏信号功率和噪声功率,待迭代终止时,对稀疏信号功率谱峰搜索,即可实现对目标的方位估计。仿真结果表明,与现有非均匀噪声下的估计方法相比,所提方法提高了非均匀噪声情况下声矢量传感器阵列的方位估计精度。

一种热对流式MEMS二维质点振速传感器

由空气质点振速传感器和声压传感器组成的矢量传声器是测量声场空间信息的重要方式。本文设计了一种新型热对流式二维质点振速传感器,不同于传统平行线式传感机制,该器件由多线进行交叉连结形成一个中央十字加热器和四个直角测温线,构成新的局域加热和温度传感方式,基于此设计能够获得更高的灵敏度并具有理想的正交性。通过数值分析对其传感机制进行了详细分析,并使用MEMS工艺进行器件制备和性能验证。实验结果表明,该器件具有良好的响应灵敏度和接近完美的正交指向性。所提出器件在体积受限的声场测量中具有潜在应用价值。

基于单声矢量传声器虚拟扩展的多机动声目标跟踪算法

为解决单声矢量传声器(Acoustic vector sensor,AVS)可跟踪声目标数目少、跟踪性能差的问题,提出了基于AVS虚拟扩展的多机动声目标跟踪算法.首先,引入高阶累积量预处理过程并建立高阶似然函数,不仅能够抑制高斯噪声、提高估计精度,还可通过AVS的虚拟扩展增加可跟踪目标数目.然后,在边缘化δ广义标签多伯努利(Marginalizedδ-generalized label multi-bernoulli,Mδ-GLMB)滤波框架下,提出了基于累积量的增广运动模型状态的Mδ-GLMB(Cumulants-based augumented motion model state Mδ-GLMB,Cum-AMMS-GLMB)算法.算法引入多种运动模型,并将表征不同模型的索引标号作为目标状态的增广参数,通过各模型间的加权混合获取优于单一运动模型的跟踪性能.除此之外,算法的序贯蒙特卡洛(Sequential Monte Carlo,SMC)实现过程中,依据高阶预处理获得的归一化空间谱拟合检测概率函数,抑制了杂波向可用粒子扩展,进一步增强了高似然区域的粒子.最后,推导了AVS目标跟踪的后验克拉美罗下界(Posterior cram e’r-rao lower bound,PCRLB),并通过仿真实验验证了算法的量测噪声抑制能力和声目标跟踪性能.