Technical Approach

The technical approach is to carry the development of a prototype marine system through to a fully operational version mounted on a sled that can be towed over seeded targets on the ocean floor. The problem with using conventional EM systems in the marine environment is that there is a large response from electric currents induced in the seawater itself which masks the response from targets in the ocean bottom. The new system is based on the land-based BUD system that uses a unique configuration of receiver pairs that are operated in difference mode. Receivers placed symmetrically on either side of the transmitter coil see identical fields during the on-time of the transmitter pulse and identical fields from the induced currents in the surrounding ocean. With this configuration, the response from the seawater itself is effectively canceled yielding high sensitivity to metal objects close to one of the receivers. A basic system with a single transmitter and a limited receiver set is being developed to demonstrate this effect in SERDP project MR-2228. The project is to develop a system with a full complement of receivers and transmitters, mounted on a sled for towing on the ocean bottom and equipped with the acquisition system and software processing to identify intact UXO.