Worthmann Brian M, Song H C, Dowling David R
Department of Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
Marine Physical Laboratory, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093, USA.
J Acoust Soc Am. 2015 Dec;138(6):3549-62. doi: 10.1121/1.4936856.
Matched field processing (MFP) is an established technique for source localization in known multipath acoustic environments. Unfortunately, in many situations, particularly those involving high frequency signals, imperfect knowledge of the actual propagation environment prevents accurate propagation modeling and source localization via MFP fails. For beamforming applications, this actual-to-model mismatch problem was mitigated through a frequency downshift, made possible by a nonlinear array-signal-processing technique called frequency difference beamforming [Abadi, Song, and Dowling (2012). J. Acoust. Soc. Am. 132, 3018-3029]. Here, this technique is extended to conventional (Bartlett) MFP using simulations and measurements from the 2011 Kauai Acoustic Communications MURI experiment (KAM11) to produce ambiguity surfaces at frequencies well below the signal bandwidth where the detrimental effects of mismatch are reduced. Both the simulation and experimental results suggest that frequency difference MFP can be more robust against environmental mismatch than conventional MFP. In particular, signals of frequency 11.2 kHz-32.8 kHz were broadcast 3 km through a 106-m-deep shallow ocean sound channel to a sparse 16-element vertical receiving array. Frequency difference MFP unambiguously localized the source in several experimental data sets with average peak-to-side-lobe ratio of 0.9 dB, average absolute-value range error of 170 m, and average absolute-value depth error of 10 m.
匹配场处理（MFP）是一种在已知多径声学环境中进行源定位的成熟技术。不幸的是，在许多情况下，特别是那些涉及高频信号的情况，对实际传播环境的了解不完美会妨碍精确的传播建模，并且通过MFP进行源定位会失败。对于波束形成应用，这种实际与模型的失配问题通过频率下移得到缓解，这是由一种称为频差波束形成的非线性阵列信号处理技术实现的[阿巴迪、宋和道林（2012年）。《美国声学学会杂志》132卷，3018 - 3029页]。在此，利用2011年考艾岛声学通信多学科研究计划实验（KAM11）的模拟和测量结果，将该技术扩展到传统（巴特利特）MFP，以在远低于信号带宽的频率下生成模糊度曲面，在该频率下失配的有害影响会降低。模拟和实验结果均表明，频差MFP在应对环境失配方面比传统MFP更稳健。具体而言，频率为11.2千赫至32.8千赫的信号通过一条106米深的浅海声道传播3千米至一个稀疏的16元垂直接收阵列。频差MFP在几个实验数据集中明确地对源进行了定位，平均峰旁瓣比为0.9分贝，平均绝对值距离误差为170米，平均绝对值深度误差为10米。
