Estimation of Noise Field Directionality; Comparison with Fourier Series Method.

摘要

For a line array immersed in a stationary homogeneous noise field, the noise field directionality, at any temporal-frequency of interest, is estimated without any a priori assumptions about the field and without the limitations of ill-conditioning. The key to this development is the deferment of the inherent discretization associated with any array until after the integral equation for the noise field directionality has been solved in terms of the observed spatial correlation. Comparison with the Fourier series method reveals nearly identical results, except that the Fourier series method reveals nearly identical results, except that the Fourier series method has some inaccurate low-order Fourier coefficients. Also, no Bessel function evaluations are required for the new method proposed here; instead, one FFT suffices for approximate evaluation of the field directionality. However, neither procedure has the superresolution capability of some of the recent eigen-decomposition approaches. Keywords: Acoustic fields, Underwater acoustics; Acoustic arrays; Aliasing/smoothing; Fourier integral method; Equispaced line arrays. (edc)