EMI Sensing for Underwater Metallic Targets Detection and Classification

Electromagnetic induction (EMI) sensing phenomenon are investigated for a conducting and multilayer environment to aid in underwater unexploded ordnance (UXO) detection and classification. The marine environment introduces complexities, such salinity gradient, sharp conductivity changes at air-water-sediment etc., which adversely can affect targets EMI signals and make underwater targets classification more difficult problem than classifying the same buried targets on land. The sensitivity of a secondary EMI signal with respect the water/air and/or water/sediment boundaries and temporal (diffusive EM field propagation speed) variability of EMI fields in an underwater (UW) environment are studied and demonstrated using the unconditionally stable Crank-Nicolson finite different time domain method (FDTD).