Recent developments in sonar for EOD applications

There are a number of sonar technology development efforts ongoing to support the explosive ordinance disposal (EOD) community with direct applicability to homeland security needs as well. These efforts seek to develop enabling technologies to detect, reacquire, classify and identify moored, bottom and limpet mines. This paper will discuss the motivation for these efforts, present a description of the technology approaches, and describe initial trial results of two test bed systems developed under the Office of Naval Research (ONR) sponsored EOD applied research program. The first system is a diver-held multi-beam sonar based on charge domain processing technology. The low power electronic beamforming (LPEB) sonar was developed to enable reacquisition of previously marked contacts for the purpose of identification. It also has applications to marine searches. A key system constraint was to maximize performance within a 20W, 440 cubic inch design space. The second system is intended for inspection of ship hulls from a UUV (unmanned undersea vehicle) platform and is based on blazed array technology. The blazed array implementation creates a frequency dispersed set of subdegree conical beams in response to a broadband input signal. The set of conical beams is scanned across the hull by the UUVs forward motion. Again power and size limitations were key drivers in the development of this sonar.