Abstract:

This paper addresses the exploitation of the information contained in a signal by means of wave packet decomposition. This general technique has a wide range of signal processing applications: The application considered here is sonar systems with a particular emphasis on providing a broader view of time-frequency waveform analysis for target classification. The acoustic response of a submerged object depends on its physical shape and structure and on its elastic properties. A methodology of nonorthogonal decomposition is used to reduce the scattered echoes into wave packets associated with the important scattering mechanisms. This decomposition method is based on the energy distribution of the individual components and can be related to the structural scattering physics. In the case of a sonar target, mechanisms such as specular reflections, creeping waves, Bragg waves, and Bloch waves from the different parts of target or scattering centers can be incorporated into the target characterization. By applying pattern recognition logic, the present study can serve as a useful background for new sonar system development with advanced processing techniques and state-of-the-art computer hardware. Examples from numerical simulations and laboratory measurements are used to discuss the effectiveness of this target classification scheme. [Work supported in part by ONR.]