Above Water Electric Potential Signatures of Submerged Naval Vessels

Abstract

In this paper, we investigate the fundamental linkage between underwater electric potential (UEP) signatures and their related electric fields above the waterline, which are introduced as above water electric potential (AEP) signatures. As a first step, the field distribution for an underwater point source excitation (fundamental solution) is derived analytically, using an adjusted method of images. Subsequently a numerical approach is introduced, whereby the calculation of the stationary current density distribution and electrostatic fields are coupled within an FEM simulation. Simulation results are presented for the aforementioned point source, as well as for a submarine model, where the latter includes considering non-linear polarization curves to model the electrochemical behavior at the metal–seawater interface. Finally, the relevance of AEP signatures in the context of anti-submarine warfare (ASW) is discussed. Our results show that AEP signatures inevitably occur along with UEP signatures, and could therefore in principal be used to detect submerged submarines via airborne sensors. However, an estimation of the expectable signal-to-noise-ratio (SNR) suggests that AEP signatures are difficult to exploit and therefore entail a much lower risk compared to other signatures.

Characteristics of Electric Field Induced by Oscillating Metal Underwater Vehicle

“…In Equation (1), ∆l is the distance between electrode pairs, also known as electrode distance; U 1 represents the potential measured by sensor 1 in each pair of electric field sensors, and similarly, U 2 represents the potential measured by sensor 2 in each pair of electric field sensors; E l is the electric field between electrode pairs. According to Equation (1), for electric field measurement, the smaller the electrode distance, the more accurate it is.…”

“…As an important source of target exposure, ship electric fields have the advantages of being unable to be completely eliminated, strong anti-interference ability, and obvious line spectrum characteristics. They are often used for underwater target detection and underwater weapon fuses [1][2][3][4][5]. With the escalating conflict of international maritime rights and the progress of countries around the world in ship noise reduction and demagnetization, the detection of electric fields in water targets has attracted much attention.…”

The non-acoustic signatures of underwater vehicles

“…22,23 A more complete review of MADs is provided by Zhao et al 17 A complimentary detection method to MAD involves electric potential signatures. 24 Underwater moving vehicles generate an extremely low frequency (ELF) electric field due to galvanic currents flowing in the water around the hull. 25 The fundamental frequency of the ELF emissions is related to the speed of the vessel, which means that a frequency analysis can reveal information about the vessel movements.…”

Active Electric Anomaly Detection Method for Underwater Targets Based on the Orthonormal Basis Function

“…Ren et al [13] developed an amplitude information-frequency characteristic recognition algorithm to improve the measurement accuracy and used three multi-frequency excitation types, the signals-square wave, single pulse, and biphasic pulse, to detect objects underwater. In order to detect naval submarines, Schaefer et al [15] derived analytic expressions for above-water electric potential fields and presented numerical simulations which coupled the calculation of the stationary current density distribution with electrostatic fields.…”