Active Broadband EM Detection and Classification of Buried Naval Mines

"We propose a new active broadband electromagnetic (EM) sensor to detect and classify naval mines buried in the littoral. The sensor will work like an underwater metal detector, but it will operate at multiple programmable frequencies suitable to a givenlittoral environment. Once it detects a potential target, the sensor will interrogate the target and measure its spectral responses (inphase and quadrature) over the entire operating bandwidth. The sensor will then compare the measured spectrum with alibrary of spectra stored for mines that are known or presumed to occur in the survey area. The process will generate a rank-ordered list of spectral matches. As the sensor finds new mines at a site, it can expand its spectral library - a "learn as you go"approach. The proposed active EM sensor can be used as a "confirmation sensor" when it is integrated with other sensors such as passive magnetometers and sonars. A mathematical framework will be developed to interface this data with fusion algorithmsbeing pursued for buried minehunting. In addition, the sensor will serve in a dual role to simultaneously measure the conductivities of the seawater and bottom sediment, which can be used to derive sediment density and porosity, providing importantenvironmental data for mine warfare.Target classification based on the spectral fingerprints is called Electromagnetic Induction Spectroscopy or EMIS. It is known that an EMIS spectrum depends on t