Underwater EMI Sensor Platform for Metallic Item Detection

Dr. Shawn Mulvaney | U.S. Naval Research Laboratory

MR-201610

Objective

The technological focus of this project was to replace the electromagnetic induction (EMI) sensor array originally designed for the Marine Towed Array (MTA), developed under Strategic Environmental Research and Development Program and Environmental Security Technology Certification Program funding, with one based on advanced EMI electronics and sensor designs.

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Technology Description

The technological focus of this project was to replace the electromagnetic induction (EMI) sensor array originally designed for the Marine Towed Array (MTA), developed under Strategic Environmental Research and Development Program and Environmental Security Technology Certification Program funding, with one based on advanced EMI electronics and sensor designs.

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Interim Results

The upgraded EMI array performs as well in salt water as it does on land. Transmit currents are lower than planned (8.3 versus 20 A), due to limitations in the plan to modify the original transmitter. Additionally, York River noise levels encountered experimentally are two to three times larger than those seen in air, on land during our testing at Blossom Point. To improve signal to noise ratio to the levels required to meet the project’s design goals would require either or both: a) new transmitter loops with heavier gauge wire, or b) a new bipolar transmitter capable of using higher supply voltages.

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Benefits

The MTA’s EMI array was successfully upgraded to incorporate a more modern, AGC-grade EMI data acquisition system, transmitter loops, and tri-axial receiver cubes. All existing MTA systems were successfully reactivated or replaced after years of storage. Notionally, there are no new implementation issues for the MTA. The MTA was and remains ideally suited for deployment in relatively flat-bottoms, open areas such as bays where munitions transfers occurred ship to ship.

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Points of Contact

Principal Investigator

Dr. Shawn Mulvaney

U.S. Naval Research Laboratory

Phone: 202-404-2120

Program Manager

Munitions Response

SERDP and ESTCP

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