Design of a synthetic aperture array to support experiments in active control of scattering
By: by James P. Dullea
Contributors: Massachusetts Institiute of Technology
Publisher: Available from the National Technical Information Service; Massachusetts Institute of Technology
Published: 1990
Place of publication: Springfield, Va; Cambridge, Massachusetts
Language: eng
Number of pages: 137
Description: A synthetic aperture acoustic array is used to as a spinal filter in a reverberant test facility. The array is used to examine the change in the received signal when a fluid loaded steel plate is replaced by the free surface. Twenty millisecond active pulses at 2 kHz were scattered by the target plate and recorded by the synthetic aperture array for post processing. The method of reverberant field subtraction was utilized and found unsatisfactory for use with signals of 20 msec duration in a reverberant tank. Array processing using a rectangular amplitude function was marginally successful. A Chebyshev amplitude weighted array was successfully used to demonstrate the ability of a linear array to discriminate between the steel plate and free surface scattering. A computer aided interactive design tool was written to aid in the analysis of array architectures by calculating hydrophone amplitude weights, beamwidth, directivity index and graphically presenting the normalized directional beampattern. The program allows comparative analysis of two array designs simultaneously.
Notes: ADA226642.

"June 1990."

CIVINS.

Thesis (Degree of Naval Engineer and M.S. in Mechanical Engineering) Massachusetts Institute of Technology, June 1990.

Includes bibliographical references.