Abstract:
Mine counter measures (MCM) sonars have seen accelerated development over the last few years as Navy interests have shifted into shallow-water operations. To find mines, most MCM sonar technologies use relatively high-frequency and narrow-band signals to produce high-resolution images of the seafloor. Even so, the problem of discriminating between proud mines and similarly sized false targets and of detecting buried mines at ranges of several hundred meters remains very difficult. The Applied Physics Laboratory-University of Washington in conjunction with Arete Engineering and Technologies Corporation-San Diego have been conducting shallow-water experiments with a relatively low-frequency and very broadband (2--20 kHz) sonar. The use of low frequencies permits greater penetration into bottom sediments and very broadband signals mitigate the lack of spatial resolution expected from a narrow-band analysis. A description of the sonar and of the experiments conducted in Puget Sound using mines and minelike false targets will be presented, as well as some preliminary results illustrating the kinds of signal processing approaches that have been developed.