Vessel detection using extremely low frequency magnetic anomaly detection signal


  1. Birsan, M.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
Extremely low frequency (ELF) electromagnetic fields generated from a vessel are often measured with bottom-mounted systems. Research at DRDC has shown that these ELF magnetic fields can be detected with the magnetic anomaly detection (MAD) system suspended from a helicopter (towed body). However, to detect a vessel at a tactically useful range with the ELF signal only, the signal to noise ratio (SNR) has to be substantially improved. This paper addresses the problem of ELF signal enhancement in noisy environments when only the noisy (after the normal aircraft compensation) MAD signal from a scalar magnetometer is available. A variety of ELF noise sources were examined in conjunction with the noise floor required in order to make detection at a given range. The signal processing algorithms to detect ELF signatures already exist for acoustic detection and can be adapted easily. The noise reduction technique is expressed as a short-time spectral gain depending on the a priori SNR. It is shown that, when applied to real data, the enhanced ELF signal offers improved target detection and can provide information about the target heading.
magnetic anomaly detection;ship magnetic signature;signal processing
Report Number
DRDC-RDDC-2017-N034 — External Literature
Date of publication
01 Nov 2017
Number of Pages
Electronic Document(PDF)

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