Frequency-Domain Electromagnetic Induction Sensors for the Multi-Sensor Towed Array Detection System

2002 ◽  
Author(s):  
H. H. Nelson ◽  
B. Barrow ◽  
T. Bell ◽  
R. S. Jones ◽  
B. SanFilipo
Keyword(s):  
Frequency Domain ◽  
Electromagnetic Induction ◽  
Detection System ◽  
Array Detection ◽  
Towed Array

scholarly journals Identification and Removal of Non-acoustic Noise in Towed Array Sonar Using F-Κ Transform for Enhanced Torpedo Detection

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Vibration Isolation ◽  
Acoustic Noise ◽  
Detection System ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Noise Sources ◽  
Towed Array ◽  
Spatio Temporal ◽  
Towed Arrays

Low frequency passive towed array sonar is an essential component in a torpedo detection system for surface ships. Compact towed arrays are used for torpedo detection and they will be towed at higher towing speeds compared to conventional towed array sonars used for surveillance. Presence of non-acoustic noise in towed array sensors at higher towing speeds degrades torpedo detection capability at lower frequencies. High wavenumber mechanical vibrations are induced in the array by vortex shedding associated with hydrodynamic flow over the array body and cable scope. These vibrations are known to couple into the hydrophone array as nonacoustic noise sources and can impair acoustic detection performance, particularly in the forward end fire direction. Lengthy mechanical vibration isolation modules can isolate vibration induced noise in towed arrays, but this is not recommended in a towed array which is towed at high speeds as it will increase the drag and system complexity. An algorithm for decomposing acoustic and non-acoustic components of signals received at sensor level using well known frequency-wavenumber transform (F-K transform) is presented here. Frequency-wavenumber diagrams can be used for differentiating between acoustic and non-acoustic signals. An area of V shape is identified within the F-K spectrum where acoustic energy is confined. Energy outside this V will highlight non-acoustic energy. Enhanced simultaneous spatio-temporal and spatio-amplitude detection is possible with this algorithm. Performance of this algorithm is validated through simulation and experimental data.

Frequency domain electromagnetic induction survey in the intertidal zone: Limitations of low-induction-number and depth of exploration

2014 ◽  
Vol 100 ◽  
pp. 14-22 ◽  
Author(s):  
Samuël Delefortrie ◽  
Timothy Saey ◽  
Ellen Van De Vijver ◽  
Philippe De Smedt ◽  
Tine Missiaen ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Intertidal Zone ◽  
Electromagnetic Induction

Sensitivity of multi-coil frequency domain electromagnetic induction sensors to map soil magnetic susceptibility

2010 ◽  
Vol 61 (4) ◽  
pp. 469-478 ◽  
Author(s):  
D. Simpson ◽  
M. Van Meirvenne ◽  
E. Lück ◽  
J. Rühlmann ◽  
T. Saey ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Frequency Domain ◽  
Electromagnetic Induction ◽  
Soil Magnetic Susceptibility
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