时域实现结构球面阵的最差性能优化稳健宽带波束形成器设计

针对球面阵模态域波束形成器对传声器失配误差敏感的问题,研究了时域实现结构球面阵的最差性能优化稳健宽带波束形成器设计。揭示了波束响应误差上界的保守性是影响现有最差性能优化方法性能的主要原因,进而提出了一种波束响应误差上界更为紧凑的优化设计方法。理论分析表明,与现有最差性能优化方法相比,所提出方法的代价函数更小、且可行解的范围也更大。针对最差性能优化设计方法存在的波束指向上阵列响应随频率变化波动偏大而引起信号失真的问题,还给出了一种减小波束图在指向方向上受信号频率影响的约束方法。仿真分析结果表明:在相同传声器失配误差条件下,所提出的设计方法要优于现有方法,得到的波束图具有更低的旁瓣级。      

融合插值点优化的多项式结构宽带波束形成器设计方法

多项式结构设计方法是主瓣指向可调宽带波束形成器设计的一类重要方法。多项式结构的阶数是有限的,导致主瓣实际指向与期望指向之间存在偏差,因而影响了波束形成器的指向性指数。针对这一问题,该文提出了一种基于插值点优化的多项式结构宽带波束形成器设计方法。首先,引入多项式结构插值点处阵列响应的空间导数约束,以减小主瓣指向偏差;进而利用粒子群优化算法对多项式结构中的插值点进行优化,以充分利用插值点位置提供的自由度进一步提升多项式结构宽带波束形成器的性能。优化设计结果表明,与现有设计方法相比,该文提出的方法不仅降低了主瓣的指向偏差,同时也提高了指向性指数,有效改善了多项式结构宽带波束形成器的性能。     

Design of broadband beamformers based on an expected response interpolation technique

A method for designing broadband beamformers based on an expected response interpolation technique was proposed, with the aim of reducing the heavy optimization burden in the broadband beamformer design problem. In the method, some typical frequencies in the designing frequency band are selected and the optimal array weights are designed on these typical frequencies, based on which a broadband expected response function is constructed. Then, FIR filters are designed to realize the broadband beamforming over the whole designing frequency band, via the interpolation technique which is utilized to the expected responses of the FIR filters. Broadband beamforming can be fulfilled by applying these filters to each of the sensors in the array. By using the proposed method, designers need not to divide the whole designing frequency band into narrow subbands so as to make the narrow band assumption valid, which not only reduces the heavy designing burden, but also releases the requirement for measurements at fine frequency grids in the robust beamformer design. Results of both computer simulations and watertank experiments verify the effectiveness of the proposed method.     

Nearfield broadband array design using a radially invariant modal expansion

This paper introduces an efficient parameterization for the nearfield broadband beamforming problem with a single parameter to focus the beamformer to a desired operating radius and another set of parameters to control the actual broadband beampattern shape. The parameterization is based on an orthogonal basis set of elementary beampatterns by which an arbitrary beampattern can be constructed. A set of elementary beamformers are then designed for each elementary beampattern and the desired beamformer is constructed by summing the elementary beamformers with frequency and source-array distance dependent weights. An important consequence of our result is that the beamformer can be factored into three levels of filtering: (i) beampattern independent elementary beamformers; (ii) beampattern shape dependent filters; and (iii) radial focusing filters where a single parameter can be adjusted to focus the array to a desired radial distance from the array origin. As an illustration the method is applied to the problem of producing a practical array design that achieves a frequency invariant beampattern over the frequency range of 1:10 (which is suitable for speech acquisition using a microphone array), and with the array focused either to farfield or nearfield where at the lowest frequency the radial distance to the source is only three wavelengths.     

基于自适应加权约束最小二乘法的麦克风阵列稳健频率不变波束形成算法

为了解决麦克风阵列通道失配时波束形成算法的稳健性问题, 提出一种基于自适应加权约束最小二乘法的麦克风阵列稳健频率不变波束形成算法. 该算法在分析无通道失配和通道失配时阵列模型特点基础上, 深入研究了通道失配时约束最小二乘频率不变波束形成算法存在的问题及其产生的原因; 将麦克风特性的概率密度函数作为稳健因子加入到约束最小二乘频率不变波束形成算法后, 其频率不变性的稳健性得到了一定的提高, 但稳健性仍较差. 为了进一步提高约束最小二乘法频率不变波束形成算法的稳键性, 通过定义代价函数中控制频率不变性的动态加权系数来调节旁瓣频谱能量, 大大提高了频率不变波束形成算法的稳键性, 将频率不变的频带范围内同一到达角度上不同频率所形成的阵列响应的最大值与最小值之比定义为波动误差, 并作为比较本文算法与约束最小二乘稳健波束形成算法和minmax稳健波束形成算法在通道失配时频率不变性稳键性的评价指标. 算法实例验证结果表明, 在麦克风阵列通道失配时, 本文算法的波动误差最小、频率不变波束形成稳健性最好, 而且适用于任意结构的阵列.     

稳健宽带波束形成器设计的低阶统计量法*

由于传声器阵列通常对阵元失配误差较为敏感,因此稳健波束形成器的设计已成为传声器阵列处理领域的研究热点之一。概率密度法是目前传声器阵列稳健波束形成器设计中的一类重要方法,但该方法所需的阵元失配误差的概率密度信息在实际中较难获取。针对这一问题,本文研究了基于阵元失配误差低阶统计量的稳健波束形成器设计方法,该方法仅利用在实际中较易获取的阵元失配误差的一阶和二阶统计量信息。本文分别研究了基于阵元失配误差低阶统计量的固定权和变加权最小二乘波束形成器设计,给出了两种波束形成器的相关设计理论。理论和仿真分析表明,在小误差条件下,低阶统计量法所设计的波束形成器仍保持与概率密度法相当的性能。     

Optimal array pattern synthesis for broadband arrays

Broadband beamformers with constant mainlobe response over the frequency of interest are desirable in many applications including underwater acoustics, ultrasonics, acoustic imaging and communications, and so on. Solutions to this problem have been presented for specific array geometry often requiring a larger number of sensors. And the array pattern synthesis error minimization is employed for the whole field of view, which leads to suboptimal designs. In this paper, a broadband array pattern synthesis approach to designing time-domain constant mainlobe response beamformer is proposed. By imposing constraints both on the mainlobe spatial response variation over frequency and on the sidelobes of the beamformer, several optimization criteria are presented and the corresponding convex second-order cone programming implementations are given. In this approach, no preliminary desired beampattern is required and the beam responses variation minimization is employed only in the mainlobe region and not in the sidelobe regions, which improves the beamformer mainlobe synthesis accuracy. Equally, one can obtain lower sidelobes at the same mainlobe synthesis accuracy. This approach is applicable to arrays with arbitrary geometry. Simulation and experimental results are presented to illustrate the effectiveness of this approach. Performance comparisons of the proposed beamformers and the existing beamformer are also provided.     

一阶指向可调差分阵列的前后向比分析与优化设计

一阶指向可调差分传声器阵列具有尺寸小、主瓣指向灵活可调、以及阵列响应不随频率变化等优点,因而在音频处理领域得到了重要关注。但差分传声器阵列对阵元失配误差较为敏感,在实际设计中需要予以考虑。前后向比直接反映了传声器阵列对后向噪声干扰的抑制程度,是差分传声器阵列设计中的重要指标。本文从理论上深入剖析了失配误差对一阶指向可调差分传声器阵列前后向比性能的影响,揭示了其中蕴含的规律。在此基础上,针对实际中同时存在随机失配误差情况,提出了一种最差性能优化设计方法。仿真实验和实测实验验证了本文理论分析的正确性和所提优化设计方法的有效性。      

Acoustic analysis by spherical microphone array processing of room impulse responses

Spherical microphone arrays have been recently used for room acoustics analysis, to detect the direction-of-arrival of early room reflections, and compute directional room impulse responses and other spatial room acoustics parameters. Previous works presented methods for room acoustics analysis using spherical arrays that are based on beamforming, e.g., delay-and-sum, regular beamforming, and Dolph-Chebyshev beamforming. Although beamforming methods provide useful directional selectivity, optimal array processing methods can provide enhanced performance. However, these algorithms require an array cross-spectrum matrix with a full rank, while array data based on room impulse responses may not satisfy this condition due to the single frame data. This paper presents a smoothing technique for the cross-spectrum matrix in the frequency domain, designed for spherical microphone arrays, that can solve the problem of low rank when using room impulse response data, therefore facilitating the use of optimal array processing methods. Frequency smoothing is shown to be performed effectively using spherical arrays, due to the decoupling of frequency and angular components in the spherical harmonics domain. Experimental study with data measured in a real auditorium illustrates the performance of optimal array processing methods such as MUSIC and MVDR compared to beamforming.     

矩阵预滤波器在抗运动干扰中的应用研究

自适应波束形成器容易受到运动干扰和观测方向偏差的影响,针对该问题提出了一种基于矩阵预滤波的零陷展宽稳健波束形成算法。首先分析了矩阵预滤波器在抗运动干扰时的适应性,并利用矩阵预滤波器在运动干扰所在区域形成凹槽。利用椭圆投影定理计算预滤波后的导向矢量不确定集,在新的导向矢量不确定集下利用稳健Capon波束形成算法(RCB)寻找最优导向矢量。仿真分析表明,和RCB算法相比,该算法不仅获得更高的输出信干噪比,还获得了预先设定的展宽零陷。     

采用球谐分解的二范数广义逆波束形成

基于传声器阵列的声成像技术是解决噪声源识别的有效途径之一.该文提出了一种基于球谐分解的L2范数广义逆波束形成算法,并对此算法在分布式球形阵列布放方案下进行了定位精度及鲁棒性的对比分析研究.仿真结果显示,此算法对低频相干声源具有较高的空间定位精确度,且阵元位置误差对此算法性能的影响有限.通过在半消声室进行实验进一步证明了...     

Directional far-field response of a spherical nanoantenna

We study the directional far-field response of a spherical nanoantenna via engineering the plasmonic nanosphere's distance, size, and material. A unified pattern synthesis approach based on the T-matrix method and the particle swarm optimization is proposed for the directional beamforming of the nanoantenna. The angular response of the directional nanoantenna is very sensitive to the material change but is immunized to the random error of the spatial position of each particle. The physical origin of the high directionality is attributed to the coherent near-field distribution with large correlation length. This work provides the fundamental theory and physics for future nanoantenna design.     

宽带波束形成器的设计与实现（英文）

The designs and implementations of broadband beamformers are reviewed and discussed.Broadband beamformer includes discrete Fourier transform(DFT) implementation of a frequency-domain beamformer and finite impulse response(FIR) implementation of a timedomain beamformer.The designs of weights at each frequency bin for the DFT beamformer and that of FIR filters associated with each sensor for the FIR beamformer are both introduced.Performance analysis and comparisons for several typical approaches to them are presented.A unified approach,i.e.,multiple-constrained approach,to narrowband beamformer is provided and is extended to the FIR implementation of broadband case.The unified approaches include the existing individual approaches as their special cases,which leads to much more flexible designs.Design examples of broadband robust adaptive beamformer with constant mainlobe response and controlled sidelobes are given to illustrate the behavior.     

Noise suppression using the coherent onion peeler

An innovative noise suppression algorithm, called the coherent onion peeler (COP) (patent detained) is derived by minimizing the error in the coherent subtraction of the data from a single plane wave model. The COP solution "collapses" for all beamforming algorithms to the same solution at the complex hydrophone FFT level. Thus, any beamformer can be applied to the residual FFTs after the COP has been applied. The COP is applied to the strongest interferer first and the residual FFTs represent the acoustic field with this interferer coherently "peeled back" like the outer skin of an onion. This procedure can be repeated any number of times to coherently suppress the noise from all interferers present. A new nonadaptive beamformer is developed that "blends" together the best beam pattern properties of conventional beamforming (CBF) near array design frequency and the generalized fourier integral method (GFIM) at very low frequencies (VLF). In between these frequency extremes, the GFIM-CBF Blend (patent pending) (G-C Blend) is a frequency-dependent weighted average of both individual beamformers. COP and G-C Blend are applied to the broadband noise emitted by the tow ship, which severely degrades the performance of the towed array; COP reduced this broadband noise by over 19 dB in a single pass.     

三维空间非同步测量高分辨率声成像方法

为解决三维空间中声源成像分辨率低的问题,提出一种基于非同步测量的三维空间声成像方法.该方法首先通过移动球形传声器阵列扫描空间分布的声源,然后利用非同步测量技术近似得到大孔径、高密度的传声器阵列测量结果,最后通过传统波束形成算法成像.仿真及实验结果表明,该方法与单次测量下的波束形成方法相比,聚焦性能更好,空间分辨率高,可...     

有距离辨识度的传声器阵列波束优化算法研究*

小尺度线性传声器阵列在便携式通信设备中具有潜在应用前景,其波束优化算法大多关注于抑制来自与声源不同方向的噪声,而不能有效地抑制与声源同方向的噪声。本文通过对几种典型波束优化策略进行改进,增加线性约束条件,使得阵列兼具方向和距离辨识度。论文对比了几种优化方法的波束性能,同时讨论了约束条件对波束旁瓣的影响,并提出了鲁棒性的优化方案。仿真结果显示,合理的优化策略和线性约束条件可以使阵列波束获得很好的聚焦性能。     

基于信号子空间重构的鲁棒子区域Frost波束形成

本文针对一个感兴趣子区域内的宽带波束形成问题, 提出一种基于信号子空间重构的鲁棒Frost波束形成算法. 该算法的基本思想是利用一个矩阵滤波器从所估计的信号加干扰子空间中提取感兴趣信号(SOI)的特征分量; 然后利用该特征分量重构信号子空间; 最后利用重构的信号子空间构造一组线性约束最小方差(LCMV)准则, 来保证SOI近似无失真通过. 与现有的其他鲁棒Frost波束形成算法相比, 本文算法的一个显著优点是在未知SOI实际波达方向与频带等先验信息的情况下, 其导向与带宽均能够自适应地匹配SOI. 因此在整个感兴趣子区域内, 它都能获得接近最优值的输出信干噪比. 理论分析与仿真研究验证了算法的有效性.     

Automatic 3D scanning surface generation for microphone array acoustic imaging

This work presents a new technique for automatically generating the 3D scanning surface for acoustic imaging using microphone arrays. Acoustic images, or maps, of sound coming from spatially distributed sources, may be generated from microphone array data using algorithms such as beamforming. Traditional 2D acoustic maps can contain errors in the near-field if the object being imaged has a 3D shape. It has been shown that using the 3D surface geometry of an object as a scanning surface for beamforming can provide more accurate results. The methods used previously to generate this 3D scanning surface have either required existing CAD (Computer-Aided Design) models of the object being acoustically imaged or have required separate equipment which is generally bulky and expensive. The new method uses one or more cameras in the array, a data projector, and structured light code to automatically generate the 3D scanning surface. This has the advantage that it is inexpensive, can be incorporated as an add-onto existing microphone arrays, has short scan time, and is capable of being extended to imaging dynamic scenes. This technique is tested using beamforming and CLEAN-SC (CLEAN based on spatial Source Coherence) algorithms for a spherical array and an Underbrink multi-arm spiral array. For sound sources located about 1.2 m from the array, the mean position errors obtained are 6 mm. This is a quarter of the diameter of the mini-speakers being used as a sound sources.     

球谐域混叠消除最优波束形成方法EI北大核心CSCD

为解决现有的球谐域混叠消除波束形成方法设计目标单一、难以很好地兼容多变的应用场景的问题,提出了球谐域混叠消除最优波束形成方法,并建立了其二阶锥规划形式的多重约束凸优化数学模型。得益于该数学模型,提出了旁瓣约束的混叠消除最大指向性波束形成器、鲁棒的混叠消除最大指向性波束形成器、混叠消除最小方差无失真响应波束形成器、零点约束的混叠消除最大指向性波束形成器。提出方法继承了现有球谐域混叠消除波束形成方法的混叠消除功能,且能够在指向性指数、白噪声增益、旁瓣水平等多个冲突的性能指标之间寻求适宜折中,便于用户根据实际应用需求灵活地调整约束参数得到特定场景下综合性能最优的波束形成器。     

用于自适应波束形成语音增强的球谐域掩蔽函数估计方法

提出一种用于球形阵列自适应波束形成的掩蔽函数估计方法.该方法利用包含空间信息的球谐系数提取低维空间向量,并采用复高斯混合模型和深度学习两种方案来估计掩蔽函数,最终利用估计的掩蔽函数设计最小方差无失真响应波束形成器,以达到空域滤波的效果.理论分析和仿真实验证明,对于相同时长的声信号,球谐域掩蔽函数估计方法的计算复杂度比传...