Application of adaptive beamforming to geoacoustic inversion and source localization

Utilizing sources of opportunity to perform simultaneous geoacoustic inversion and localization has been established using conventional beamforming (CBF) applied to data from subapertures of a bottom‐mounted horizontal line array. [R. A. Koch and D. P. Knobles, ‘‘Geoacoustic inversion with ships as sources,’’ J. Acoust. Soc. Am. 117, 626–637 (2005)] Often, multiple sources may coexist within a field, and isolating a single source is desirable prior to performing inversions. Spatial filtering has been shown to improve localizations by focusing on bearing regions containing the source of interest. [S. A. Stotts, ‘‘A robust spatial filtering technique for multisource localization and geoacoustic inversion,’’ J. Acoust. Soc. Am. 117, 139–162 (2005)]. Adaptive beamforming (ABF) is an alternative approach used to suppress noise and increase the signal‐to‐noise ratio for sources of interest. Comparisons between previous CBF inversion results and ABF inversions applied to a known data set will be presented. The inversion algorithm uses simulated annealing with a cost function correlating cross‐spectral data from the subapertures with modeled cross spectra.