REALIZATION OF A COMPUTER-AIDED PARTIALLY ELECTRONIC SCANNING TELESCOPIC MICROPHONE SYSTEM EQUIPPED WITH A SPHERICAL ARRAY FOR MONITORING OR DIAGNOSING NOISY MACHINES IN A FACTORY

摘要

This article presents an optimum design of gains in a computer-aided telescopic microphone system equipped with a spherical array for monitoring or diagnosing noisy machines in a factory. Based on the previous results, it is formulated by maximizing SNR enhancement ratio at the focusing point, whether passive dynamic focusing and spherical wave-synthesis are adopted or not. The unique solution is derived under a constraint of the minimum required sensitivity at the point. The fundamental characteristics of the optimal system are theoretically discussed from viewpoints of two extreme cases, i.e., far-field and near-field sources, resulting in the characteristics being equivalent and superior to those of the corresponding previous ones. The special features of the system are made more clear through comparison of numerically evaluated spatial sensitivity and relative received RMS error distributions of the system with both the optimal gains and the previous for sinusoidal and/or FM signals of finite bandwidths.