Next month's meeting of the Acoustical Society of America will feature some interesting developments in anti-terrorism technology. Namely, researchers have been working on ways to prevent potential suicide swimmers from attacking ports and harbors:
Acoustics can make ports and harbors more secure. Karim Sabra of the Scripps Institution of Oceanography (xxxx@mpl.ucsd.edu) will present encouraging proof-of-concept measurements of an "acoustic tripwire" surveillance system for detecting intruders in harbor entrances. Their technique is designed for the shallow-water (less than 20 meters deep) choke points of harbor entrances, which often have high levels of ambient noise. Peter J. Stein (xxxx@scisol.com) of New Hampshire-based Science Solutions, Inc. will present the Swimmer Detection Sonar Network (SDSN), designed to be a cost-effective method to protect a large area from swimmers intending to carry out terrorist activities. The in-water system consists of sets of sonar dishes that transmit and detect sound waves. Signal-processing algorithms provide automated detection, tracking, and classification of moving objects such as swimmers. The SDSN is already available commercially for wide-scale deployment (2pEA1). Two papers presented by scientists from Stevens Institute of Technology, Hoboken (papers 2aEA4 and 2aEA5) discuss acoustic measurements in New York's Hudson River. Details of acoustic noise produced by ship traffic will be presented by Heui-Seol Roh. The measurements may provide a basis for developing systems that can detect underwater threats.
The concern is that an explosive-laden swimmer or a diver could infiltrate a key port. A number of people have been thinking about the problem of swimmer-terrorists over the past few years. This Coast Guard presentation, for example, gives some fascinating descriptions of sensors and weapons designed to stop such swimmers, including water guns, acoustic impulses, explosives and trained mammals.
