Scan-based near-field acoustical holography and partial field decomposition in the presence of noise and source level variation.
Scan-based near-field acoustical holography and partial field decomposition in the presence of noise and source level variation.
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DOI：
10.1121/1.2133717
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发表时间：
2006-01
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影响因子：
--
通讯作者：
Moohyun Lee;J. Bolton
中科院分区：
文献类型：
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作者：
Moohyun Lee;J. Bolton
实际的复合源全息测量通常采用多参考交叉谱方法，在全息投影之前，必须将测量的声场分解成空间相干的分场。实现后一种方法的公式没有明确考虑加性噪声对参考信号的影响，因此被严格限制在叠加在参考信号上的噪声可以忽略的情况下。此外，当通过在顺序的多个贴片上扫描子阵列来测量声场时，分解的部分场可能遭受由逐个扫描的声源电平变化引起的空间分布误差形式的破坏。在本工作中，描述了参考信号中包含的噪声和基于扫描的测量期间的源电平变化对局部场分解的影响，并提供了同时抑制这两种影响的综合过程。此外，还比较了两种部分场分解公式的相对性能，并描述了一种获得最佳结果的策略。所提出的方法已通过数值模拟得到验证，并已应用于亚音速射流的全息测量。
Practical holography measurements of composite sources are usually performed using a multireference cross-spectral approach, and the measured sound field must be decomposed into spatially coherent partial fields before holographic projection. The formulations by which the latter approach have been implemented have not taken explicit account of the effect of additive noise on the reference signals and so have strictly been limited to the case in which noise superimposed on the reference signals is negligible. Further, when the sound field is measured by scanning a subarray over a number of patches in sequence, the decomposed partial fields can suffer from corruption in the form of a spatially distributed error resulting from source level variation from scan-to-scan. In the present work, the effects of both noise included in the reference signals, and source level variation during a scan-based measurement, on partial field decomposition are described, and an integrated procedure for simultaneously suppressing the two effects is provided. Also, the relative performance of two partial field decomposition formulations is compared, and a strategy for obtaining the best results is described. The proposed procedure has been verified by using numerical simulations and has been applied to holographic measurements of a subsonic jet.