A PHASE SPACE VIEW OF DISPERSIVE PROPAGATION, MOMENT VARIABILITY, AND ENVIRONMENTALLY-INVARIANT FEATURES FOR CLASSIFICATION

Propagation of sound in shallow water is impacted by interactions with the ocean sur- face and bottom, which give rise to frequency-dependent spreading and attenuation (dispersion and damping). In active sonar for automatic target recognition, these propagation-induced eects can be detrimental to classification because the observed backscatter depends not only on the target but also on the propagation environment and how far the wave has traveled, resulting in increased variability in the received sonar signals. We present an approach, based on a recently developed phase space ap- proximation of dispersive propagation, for analyzing these eects on temporal moment features of the propagating signal, as well as the eect of random variability in certain channel parameters, in partic- ular target distance. We also note new features for classification that are invariant to the propagation eects of dispersion and damping.