Using cross-frequency cost functions for broadband source localization and environmental inversion

Abstract

Cost functions that are constructed by coherently summing (model-to-data) correlations over hydrophone pairs and frequency have been used successfully for source localization [E. K. Westwood, J. Acoust. Soc. Am. 91, 2777–2789 (1992)] as well as source localization and environmental inversion [Neilsen, J. Acoust. Soc. Am. (to be published)]. Although the coherent sum is usually taken over the same frequency for both data and model, it is shown that summing over other regions of the fdata⊗fmodel space is also useful and may facilitate more efficient source localization. It is shown that lines of constant fdata/fmodel correspond to different source bearings. Although looking along lines of constant fdata/fmodel can be used as a crude form of spatial filtering, a new non-plane-wave spatial filter is also constructed that helps localize sources in the presence of multiple interferers. The spatial filter employed uses the environmental model to construct its set of basis functions and is therefore theoretically capable of spatially filtering in full 3-D as opposed to just bearing, as is done in adaptive beamforming.