Homomorphic signal dereverberation for a phased array imaging system

In many sonic imaging applications the echos resulting from wall reflection, scatter transmission, and resonance due to internal wall reverberation are significant sources of distortion. These echos and reverberation produce many false target images which are usually indistinguishable from true target images using simple ad hoc correlation techniques. Of course, propagation through a linear reverberant medium may be modeled by a transfer function or linear filter for which an inverse exists. Unfortunately, this filter is not known a priori and it must be estimated from stochastic data. The sources of interest here are assumed to emit random trains of pulses. The reverberant pulse responses usually overlap in time precluding discrimination of the individual pulses. Such pulse trains are characteristic of acoustic emission (AE) signals generated during crack formation in solids. The purpose of this study is to devise a scheme to deresonate the signals received at individual array elements using minimal information about the source signal itself and its power spectrum. This will be accomplished with the use of homomorphic deconvolution.