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1.
I.IntroductionTheconceptofmatchedAieldprocessinghasbeenintroducedbyBuckerin1976I1],firsttoapplyittocalculationofpassillgsourcelocalization.Theprincipleofsourcelocalizationisthatthecorrelationfunctionofthemeasuredfieldofavertical(orhorizolltal)arrnywiththecalculatedfieldforthetruesourcepositionislargerthanthatofthemeasuredfieldwiththecalculatedforany'fictitious'sourceposition,ifallestimationsofenvironmentalparametersarebasicallycorrect.Intermsofthismethodwecallobtaillbothinformationsofsourcer…  相似文献   

2.
I.IntroductionInsha1lowsea,passivesource1ocalizationisadifficu1t,yctinterestingprob1emthathasre-ceivcdagrcatdca1ofattcnti0ninthelastfCwycars.l'-'1Theconventiona1sourccloca1izationistOmatchthercceivcdacousticdatawiththesoundficldprcdictcdbythepropagationmodcl.Thistechniqueiscallcdmatchcd-ficldproccssing(MFP).Itiscommonlyacceptcdthatinshal-low-watercnvironmcnLssoundficldcanbcwclldcscribcdbyanormal-modemodel.Accord-ingtothismodcl,thcacousticprcssurecanbecxprcsscdasalincarcombinationofthenorma…  相似文献   

3.
The purpose of this work is to investigate acoustic source localization algorithms suitable for use with distributed sensor networks. Traditional sensor networks employ a central controller; however centralized data processing in large-scale sensor networks is not always desirable because of the excessive communication and computational complexity it requires. Therefore, fully distributed localization algorithms are considered. The most important aspect of these algorithms is that they be scalable for use in large sensor networks. The scalability is achieved by forming sensor nodes into groups which collaborate to locate sources. Source locations are determined from time of arrival (TOA) information of the acoustic wave front. Two source location solution methods are used: least squares (LS) and Tikhonov regularized inversion (RI). Experimental results validate the accuracy of a distributed localization approach, and the effectiveness of the LS and RI methods are compared. Additionally, important parameters of the distributed localization algorithm are considered.  相似文献   

4.
Radiophysics and Quantum Electronics - We constructed an adaptive modal rank-reduction algorithm for acoustic source localization with a vertical sensor array operating under conditions of...  相似文献   

5.
为了避开传统的匹配场目标定位技术对环境先验知识的依赖性,提出了在均匀浅海环境中只知道少量环境参数的情况下,利用垂直接收阵和不同距离上的两枚宽带引导声源重构声场对目标声源进行定位的一种方法。这种方法主要基于简正波估计和声场重构两种关键技术,同时省去了匹配场定位技术中大量的拷贝声场计算。数值仿真主要采用线性Bartlett匹配处理器分析了目标定位效果,在信噪比高于10 d B的情况下,定位效果良好。  相似文献   

6.
匹配场处理是一种水声学和物理学相结合的信号处理技术,其在水下目标定位方面的高精度特点使得该方法受到广泛关注。匹配模处理是工作在模态空间的匹配处理方法。相对于匹配场处理方法,匹配模处理方法只处理声场中有关声源位置信息的数据(然而匹配场处理方法使用了全部声场数据),这样就可以减小环境失配对定位的影响。本文研究了在环境发生失配时,通过选取受失配影响较小的模态组合,得出的定位结果更加精确。  相似文献   

7.
贾雨晴  苏林  郭圣明  马力 《物理学报》2018,67(17):174302-174302
针对利用不同阵列对浅海环境中水下目标的定位问题,基于简正波分解方法,对组合阵的目标声源定位性能进行了研究,着力解决在实际实验环境下定位性能不够高的问题,并降低实验设备布放难度.在浅海环境下,基于匹配场理论的声接收阵可实现目标的定位,但定位性能受阵形、阵元数目等影响.通过研究不同声接收阵的简正波分解矩阵,可以有效辨别不同阵形定位性能的优劣.仿真实验表明,当某一子阵简正波分解效果较差时,会降低组合阵的定位性能.基于实际实验的需求,在对短垂直阵和组合阵性能的研究中发现,由于水平阵对接收声场的定位模糊度函数中的旁瓣有抑制效果,从而造成模糊度函数表面上旁瓣较低,定位目标的主旁瓣比有所提升的现象.仿真实验表明,不同组合阵形的定位准确度均在90%以上,基于实际应用的考虑,组合阵无疑是对定位性能和实验复杂度的折中选择.  相似文献   

8.
Matched-field replica models based on an inaccurate knowledge of geoacoustic parameters such as bottom attenuation, shear, and interfacial sound-speed discontinuities, can predict an incorrect number of propagating modes for a shallow-water channel. The resulting degradation in the matched-field ambiguity surface can be substantially reduced by obtaining optimal replica models via modal-sum-limit optimization or bottom-property inversion. The use of these techniques for multi-tone (70, 95, 145, and 195 Hz) source-tow data recorded near San Diego during the first Shallow-Water Evaluation Cell Experiment (SWellEX-1) significantly increased matched-field correlation levels and improved source localization relative to results obtained with a previous nonoptimized model. The predicted number of propagating modes was also reduced substantially. The inversion for bottom properties (attenuation, interfacial sound-speed discontinuities, no shear) provided sediment attenuation estimates which agree well with Hamilton's models and were an order-of-magnitude greater than that used in the nonoptimized model, which accounts for the reduction in the number of modes. A simulated modal decomposition using the inverted optimal replica model verifies the number of modes predicted by the modal-sum-limit optimization.  相似文献   

9.
A method for time reversal focusing with variable depth and range based on mode extraction was proposed.First,the normal modes of acoustic propagation in the shallow water are extracted by modal decomposition from the probe signals received by a source receiver array.Furthermore,a diagonal matrix and a vector determined separately by the depth and the range of the probe source are extracted from the received acoustic field data.And time reversal focusing at different depths and ranges can be achieved by modulating the depth-dependent diagonal matrix and the range-dependent vector properly.Then the diagonal matrix and the vector are modulated separately according to the depth and the range of the expected focal location to construct a new acoustic field vector.When this new acoustic field vector is retransmitted by the source receiver array in time reversal order(or phase conjugation in frequency domain),focusing of the resulting acoustic field at the expected location rather than the origin of the probe source can be obtained.Numerical simulations in typical shallow water environment demonstrate the effectiveness of the proposed method.  相似文献   

10.
This paper applies geoacoustic inversion to low-frequency narrow-band acoustic data from a quiet surface ship recorded on a bottom-moored horizontal line array in shallow water. A Bayesian matched-field inversion method is employed which quantifies geoacoustic uncertainties and allows for meaningful comparison of inversion results from different data sets. Geoacoustic inversion results for ship-noise data are compared with inversion results for multitone data from a towed controlled source collected in the same experiment, and with independent geophysical measurements. To increase the information content of low-level ship-noise data, the effect of including multiple, independent data segments in the inversion is investigated and shown to significantly reduce geoacoustic parameter uncertainties. Geoacoustic uncertainties are also shown to depend on ship range and orientation, with increased uncertainties for long ranges and for the ship stern oriented away from the array.  相似文献   

11.
一种基于模态提取的深度和距离可变的时反聚焦方法   总被引:1,自引:0,他引:1  
郭国强  杨益新  孙超 《声学学报》2010,35(4):403-413
提出了一种基于模态提取的深度和距离同时可变的时反聚焦方法。首先,通过模态提取方法从时反阵列接收的探测信号中提取出波导中传播的模态函数信息,并且进一步地从中获得一个包含探测声源深度信息的对角阵以及一个包含探测声源距离信息的向量;然后,利用模态提取获得的信息对探测声源深度信息矩阵和距离信息向量进行调整,重新构造出时反阵列的一个接收声场向量信息,使得时反发射声场聚焦的深度和距离发生变化。这种方法克服了传统时反处理只能在探测声源位置聚焦的局限性,通过对探测声源深度信息矩阵和探测声源距离向量信息进行适当的调整,可以将时反发射的声场聚焦到探测声源以外的某个期望位置上。针对典型浅海波导环境,通过计算机仿真试验验证了该方法的有效性。   相似文献   

12.
Acoustic propagation in shallow water is characterized by a set of depth-dependent modes, the modal depth functions, which propagate in range according to their horizontal wavenumbers. For inversion purposes, modal depth function estimation in shallow water is an issue when the environment is not known. Classical methods that provide blind mode estimation rely on the singular value decomposition of the received field at different frequencies over a vertical array of transducers. These methods require that the vertical array spans the full water column. This is obviously a strong limitation for the application of such methods in an operational context. To overcome these shortcomings, this study proposes to replace the spatial diversity constraint by a frequency diversity condition, and thus considers the case of a field emanating from an impulsive source. Indeed, because of the discrete nature of the wavenumber spectrum and due to their dispersive behavior, the modes are separated in the time-frequency domain. This phenomenon enables the design of a modal filtering scheme for signals received on a single receiver. In the case of a vertical receiver array, the modal contributions can be isolated for each receiver even when using a partial water column spanning array. This method thus eliminates the receiving constraints of classical methods of modal depth function estimation, although it imposes the use of an impulsive source. The developed algorithm is benchmarked on numerical simulations and validated on laboratory experimental data recorded in an ultrasonic waveguide. Practical applications are also discussed.  相似文献   

13.
总体最小二乘算法模波束形成方法研究   总被引:1,自引:0,他引:1  
易锋  孙超 《声学学报》2013,38(1):35-41
研究了模波束形成处理算法,并在此基础上提出了一种总体最小二乘算法模波束形成技术。该方法利用总体最小二乘算法修正了从垂直接收基阵数据中提取出的简正波模态函数信息,准确估计出各阶简正波模态系数,提高了对目标检测和定位的性能。针对典型的浅海波导环境,进行了计算机仿真实验,结果表明:在低频远程目标条件下,该方法与常规最小二乘算法模波束形成相比,估计出的简正波模态系数更精确,具有旁瓣低,分辨率高,定位性能好的优点。   相似文献   

14.
The influence of water column variability on low-frequency, shallow water geoacoustic inversion results is considered. The data are estimates of modal eigenvalues obtained from measurements of a point source acoustic field using a horizontal aperture array in the water column. The inversion algorithm is based on perturbations to a background waveguide model with seabed properties consistent with the measured eigenvalues. Water column properties in the background model are assumed to be known, as would be obtained from conductivity, temperature, and depth measurements. The scope of this work in addressing the impact of water column variability on inversion is twofold. Range-dependent propagation effects as they pertain to eigenvalue estimation are first considered. It is shown that mode coupling is important even for weak internal waves and can enhance modal eigenvalue estimates. Second, the effect of the choice of background sound speed profile in the water column is considered for its impact on the estimated bottom acoustic properties. It is shown that a range-averaged sound velocity profile yields the best geoacoustic parameter estimates.  相似文献   

15.
Bottom acoustic parameters have important influence on the application of underwater acoustic propagation and source location.The acoustic parameters of the seabed in the northern of the South China Sea(SCS) were inversed using the experiment data from an acoustic experiment in 2015.Based on the comprehensive analysis of the influence of the sound speed fluctuation and the geoacoustic model on seabed inversion,the multi-parameter hybrid acoustic inversion scheme is improved by selecting the equivalent mean sound speed profile(SSP) and half-infinite liquid bottom model to save the inversion dimensions in the matched field processing(MFP) inversion.The inverted bottom sound speed and density are in good agreement with the core sampling measurements.The nonlinear empirical relationship of the attenuation coefficient with frequency is given out.The inversion results are meaningful to the sound propagation research and application in the northern area of the SCS.  相似文献   

16.
李天宇  李宇  黄海宁  迟骋 《应用声学》2020,39(6):810-820
使用水下无人平台作为载体的拖曳阵进行被动目标深度估计具有灵活性高和隐蔽性好的优点,针对实际应用中存在的平台自噪声和阵列瞬时随机加速度扰动问题,提出了一种稳健的目标深度估计方法。该方法分为三个步骤,首先对阵元接收信号进行自适应噪声抵消和相位抖动滤波,然后对声压进行距离积分实现简正波模态估计,最后计算模态匹配度,最大值对应的深度为目标深度估计结果。仿真表明在干扰背景下该方法的目标深度估计稳健性优于传统方法,声源频率、合成孔径距离和信干比决定了目标深度估计误差。利用实验数据验证了该方法对水下低频线谱声源的深度估计能力。  相似文献   

17.
于梦枭  周士弘 《应用声学》2020,39(6):839-848
针对水平不变的浅海波导中单矢量传感器对低频宽带声源的三维被动定位问题,首先利用平均声强器估计声源方位;其次,通过分离简正模的声压和水平振速分量联合处理获得运动声源相对速度,进一步基于垂直声能流中简正模相干项特征频率不变性以及长时间窗口中多快拍信号的统一处理,建立WARPING变换频谱作为代价函数的搜索处理器,估计该段信号的初始距离,进而获得各时刻声源距离,所提出的方法避免了对拷贝声场和引导声源的依赖;最后,利用多阶简正模相干项与非相干项能量模基处理方法,当声场中存在三阶以上简正模时,可对声源深度进行匹配估计。仿真分析表明,单个矢量传感器能够给出声源的方位、距离及深度估计结果。  相似文献   

18.
A method for extracting the normal modes of acoustic propagation in the shallow ocean from sound recorded on a vertical line array (VLA) of hydrophones as a source travels nearby is presented. The mode extraction is accomplished by performing a singular value decomposition (SVD) of individual frequency components of the signal's temporally averaged, spatial cross-spectral density matrix. The SVD produces a matrix containing a mutually orthogonal set of basis functions, which are proportional to the depth-dependent normal modes, and a diagonal matrix containing the singular values, which are proportional to the modal source excitations and mode eigenvalues. The conditions under which the method is expected to work are found to be (1) sufficient depth sampling of the propagating modes by the VLA receivers; (2) sufficient source-VLA range sampling, and (3) sufficient range interval traversed by the source. The mode extraction method is applied to data from the Area Characterization Test II, conducted in September 1993 in the Hudson Canyon Area off the New Jersey coast. Modes are successfully extracted from cw tones recorded while (1) the source traveled along a range-independent track with constant bathymetry and (2) the source traveled up-slope with gradual changes in bathymetry. In addition, modes are successfully extracted at multiple frequencies from ambient noise.  相似文献   

19.
We report a full (3D) micromagnetic simulation of a set of 100 ferrite (Fe3O4) cylindrical dots, arranged in a 10 by 10 square (planar) array of side , excited by an external in-plane magnetic field. The resulting power spectrum of magnetic excitations and the dynamical magnetization field at the resulting resonance modes were investigated. The absorption spectrum deviates considerably from that of a single particle reference simulation, presenting a mode-shifting and splitting effect. We found an inversion symmetry through the center of the array, in the sense that each particle and its inversion counterpart share approximately the same magnetization mode behavior. Magnonic designs aiming at synchronous or coherent tunings of spin-wave excitations at given spatially separated points within a regular square array may benefit from the new effects here described.  相似文献   

20.
考虑到传统的匹配场处理定位需要复杂的匹配声场计算,并对环境参数和声场模型有很高的依赖,为了克服这种缺点,采用虚拟接收方法对声源进行测距。首先对垂直阵接收到的引导声源和目标声源的信号进行相关处理,得到虚拟接收声场并估计虚拟接收声场干涉条纹的斜率,结合波导不变特征量β对目标声源进行测距。通过数值仿真和2004年南海实验数据处理,讨论了浅海斜坡海域环境中不同频段下利用虚拟接收方法对宽带声源测距的性能。随着频率升高,需要展宽频带以获得完整的干涉条纹和良好的测距结果。在实验数据处理中,选取频段较高的信号时,由于阵列间距偏大不能保证采样的简正波模式的正交归一特性,不能获得正确的测距结果。   相似文献   

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