The ancient and selective history of the development of high frequency, short range, high resolution active sonars

Abstract

This is a brief history of the development of a broad class of active sonars which generally have most or all of these characteristics: relatively high operating frequency (35–1500 kHz), short range (a few meters to 1.0 km), high range resolution (1.0 m to a few cm), and high cross range resolution (a few degrees to 0.1°). Emphasis is on such sonars developed by several navies to find small objects such as naval seamines although there are other important civilian applications. Beginning with the experimental work of Paul Langevin (France) in 1916–18, the development of three generic types of sonars is traced: ahead searching, multibeam, electronic scanning sonars; continuous transmission frequency modulated sonars; and side-scanning sonars. Other types such as small boat sonars, sonars for manned and unmanned small submersibles, and 3D or camera type sonars are covered briefly. Basic research to support the development of all these sonars, primarily target strength and echo structure and bottom reverberation, is discussed only briefly as are other topics such as techniques for high cross-range resolution, target classification clues, and uses for wide bandwidth. Sonars that have proven to be historically significant are identified. The period covered is primarily 1916–1980.