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A Low Frequency Electromagnetic Sensor for Underwater Geo-Location

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Final rept.

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The research described in this report was conducted in fulfillment of Project MM- 1719, A Low Frequency Electromagnetic Sensor for Underwater Geo-Location, submitted to the Strategic Environmental Research and Development Programs SERDP Exploratory Development Program SEED in response to Statement of Need MMSEED-10-01, Advanced Technologies for Detection, Discrimination, and Remediation of Military Munitions on Land and Underwater. The main focus of this research was to explore and develop a new low frequency Electromagnetic Sensor modality for fast and accurate Geo-Location that would be based on the measured vector magnetic field, which would be sufficiently robust and efficient to be used in the real field for underwater UXO detection and discrimination systems tracking and positioning. In this project we concentrated on the fundamental mathematical, physical, computer simulation and potential practical implementations aspects of the proposed approaches. The report provides both the mathematical fundamentals and physical meanings of the proposed approach for underwater geo-location. Namely we explore two techniques for underwater geo-location using low frequency magnetic field a the first technique was based on the vector magnetic field full tensor gradient estimations at a given point, b the second uses the non-linear optimization algorithm based on the differential evolution DE approach. We studied the sensitivity of the vector magnetic field gradient estimations using the standard finite different approach. In addition we utilized the three dimensional EMI solver based on the method of auxiliary sources for estimating the noise due to a spherical and spheroidal UXO like targets. We studied the accuracy with which the system can estimate a transmitters location, their robustness with respect to noise, and their requirements with regard to data quality and quantity.

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  • Magnetic and Electric Field Detection and Detectors

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