Denoising underwater signals propagating through multi-path channels

In multipath configurations, an estimation of the channel impulse response is useful for who wants to reduce or cancel undesirable multipath effects. However, the underwater noise does not fulfill the classical white-noise assumption for which matched filer-based algorithms performs optimally. In this context, three denoising methods are studied. The first two are classical methods, based on wavelet packet (WPD) decomposition and uniform filter bank (UFB) decomposition. As an alternative, we propose a novel time-frequency denoising approach, founded on the joint use of unitary warping operators and finite impulse response filters. As shown through experimental results, the WPD-based and UFB-based denoising tools are not well-suited in a multipath context. By contrast, our proposed warping-based method gives good results and leads to an improved estimation of the channel impulse response.