A versatile signal-processing system for producing the angular and frequency distribution of acoustic energy in real time

Abstract

For a number of years the US Naval Research Laboratory (NRL) has been conducting a research program in underwater sound propagation using large aperture hydrophone arrays. This research requires the spectral and angular distributions of the sound field with a variety of bandwidth and throughput rate requirements. As the size of the aperture, in tenus of number of hydrophones, increases, the demand on the signal processing equipment increases correspondingly. In addition to this growth in processing needs, the move to at-sea, real-time systems demands high reliability and very high speeds to prevent loss of data. A sea-going signal processing system has been developed at NRL to meet these processing requirements. The system is versatile in that it is composed of a number of small array processors operating in parallel which can be redistributed to handle the varying processing loads presented by different research interests. It is designed to handle 256 irnput channels at an overall input rate of 256 kHz. The system is designed around a dual bus architecture connected by an interbus window and controlled by a single CPU. All components of the system are commercially available plug in components making replacements simple and system reliability high. This paper describes the system architecture, the system design philosophy and current operating capability.