Optimizing copper spheres for precision calibration of hydroacoustic equipment
Foote, Kenneth G.
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KeywordCalibration; Spheres; Copper; Cross sections; Backscattering; kHz range 01−100; kHz range 100−1000; Optimization; Sound waves; Echoes; Acoustic equipment; Underwater
An operational definition of backscattering cross section is developed for the wideband reception of finite echoes. This is supported by relative measurements on a set of copper spheres by each of four echo sounders operating at frequencies from 38 to 120 kHz. Experiential and theoretical arguments are advanced for the superiority of commercial, electrical–grade copper in the application. An optimization problem for determining the sphere size is then formulated, and solved for the case of calibration of a 38 kHz echo sounder by a sphere of the described material. The solution: that the copper sphere diameter be 60.00 mm, is tested through a variety of measurements. These demonstrate an accuracy of 0.1 dB. The further exercise of theory indicates the feasibility of precision calibration of diverse hydroacoustic equipment by copper spheres over most of the kilohertz frequency range.
Author Posting. © Acoustical Society of America, 1982. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 71 (1982): 742-747, doi:10.1121/1.387497.
Suggested CitationJournal of the Acoustical Society of America 71 (1982): 742-747
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Foote, Kenneth G. (Acoustical Society of America, 1983-03)Effects of variations in quantities influencing the backscattering cross sections of solid elastic spheres are studied through a particular case. This is that of the 60‐mm‐diam copper sphere, which is being used worldwide ...
Foote, Kenneth G.; MacLennan, David N. (Acoustical Society of America, 1984-02)The properties of calibration spheres made from electrical‐grade copper, denoted Cu, and tungsten carbide with 6% cobalt binder, denoted WC, are examined theoretically. Effects of variations in material, medium, and equipment ...
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