Sequential classification of spherical acoustic objects in motion

An important problem in active sonar is the classification of objects from their returned scattered acoustic pressure field. Since in active sonar the insonifying waveform is usually broadband the received pressure is processed by matched filtering. After matched filtering an object´s spectrum often contains sufficient information for classification. However, when objects are similar motion modifies their spectra enough so that the probability of false classification increases. In this paper the object´s motion is first extracted and then sequential classification proceeds based on its measured fourth-order cumulant spectrum for each active sonar return and known fourth-order cumulant spectra of objects with similar velocity. The fourth-order cumulant spectrum is used because of its unique properties of noise suppression and feature extraction