High resolution spectrum estimation of virtual array based on FIM

Abstract

Underwater small aperture sonar spectral estimation methods are limited by physical dimensions, resulting in insufficient azimuthal resolving power. In this paper, we propose that based on the Fourier Integral Method(FIM) equivalent to a virtual array of extended aperture, after using subarray smoothing, combined with the spectral estimation method, we get the improved FIM-CBF, FIM-Capon and FIM-MUSIC, and give the applicable conditions of these three improved methods, and use the virtual aperture expansion and noise averaging suppression, to achieve the improvement of the azimuthal resolving power of the spectral estimation method under the low SNR.