WAVELET-BASED DENOISING OF UNDERWATER ACOUSTIC-SIGNALS

Underwater environmental measurements of the ocean require signals tha t are free from unwanted backscatter and clutter. Removing these unwan ted signal components usually amounts to applying some form of filteri ng technique such as a high pass filter, a bandpass filter, a Wiener f ilter, etc. These approaches however are limited in their abilities to remove acoustic returns that vary spectrally. This paper presents a m ultiresolution approach to removing unwanted backscatter from high-fre quency underwater acoustic signals and compares it to high pass filter ing of the same signals. The filtering approach presented applies wave let transforms for signal recovery and denoising of high-frequency aco ustic signals. It is shown that by computing a wavelet transform of th e returned signals, applying a denoising technique, and then reconstru cting the signal, additional unwanted backscatter can be removed. (C) 1997 Acoustical Society of America.