Bistatic Localization of Objects in Very Shallow Water

Bistatic or multi-static systems use spatially distributed sources and/or receivers to ensonify scattering objects over a distance to obtain the acoustic images of individual targets for classification purposes. The targets need to be localized first and separated from the clutter. To reach targets at a distance, low frequency sound is often used; targets can in principle be classified based on the frequency and azimuthal angle response of the echo return, referred to as acoustic color. Practical application of this technology is limited by the array size and the ability to localize the target and extract the scattering echo. Deconvolution of conventional beamforming (CBF) has been shown to achieve a narrow beam width and low side lobe levels equivalent to CBF of an array of much larger aperture. This method is applied to active sonar in this paper. Analysis of simulated and tank experimental data demonstrated a better separation of targets and a higher target-to-reverberation ratio than that using CBF.