An experimental apparatus has been developed as part of a continuing program of deep-sea acoustic scattering research. It consists of a computer-based shipboard console and a cable-suspended package, which contains the acoustic sources and receivers. The computer provides for preprocessing recording, and display of the data, and for control of the experimental sequence. The sensor package operates at depths to 1600 m, acquiring scattering data for eight frequencies from 4 to 25 kHz, as well as environmental parameters. [This report represents the results of research sponsored by the Office of Naval Research.]
A 48-element, 256-beam, 25-kHz sample-rate programmable DIMUS processor is currently being constructed to work with a variety of arrays on the research platform FLIP. The design approach eliminates the need for a discretionary hard-wired steering matrix, while the system clock rate remains essentially the same as for a serial beamformer of conventional design. The processor is easily reprogrammed for different array configurations or for changes in the set of beam steering directions. Although the technique has been developed specifically for a single bit DIMUS beamformer (using clipped hydrophone outputs) it is equally applicable to multiple level Digital Multibeam Steering Systems.
An experimental apparatus has been developed as part of a continuing program of deep-sea acoustic-scattering research. It consists of a computer-based shipboard console and a cable-suspended package which contains the acoustic sources and receivers. The computer provides for preprocessing, recording, and display of the data, and for control of the experimental sequence. The sensor package operates at depths to 1600 m, acquiring scattering data for eight frequencies from 4 to 25 kHz.
A clipped array simulator has been developed for use in testing and evaluation of DIMUS beamformers and associated processors. It provides 96 simulated clipper outputs, consisting of two directional signals plus uncorrelated noise. Steering and signal-to-noise ratio for each of the two signals are externally controlled either by a paper tape reader, using a program tape prepared in advance, or by an on-line computer. Mixing of the signals and noise is performed on the binary data, using a time partitioning technique, which is shown to produce the same correlation matrix as would analog summation followed by clipping.
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