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Synnes, S.A.V. (author), Hunter, A.J. (author), Hansen, R.E. (author), Sabo, T.O. (author), Callow, H.J. (author), van Vossen, R. (author), Austeng, A. (author)Wideband and widebeam synthetic aperture sonar (SAS) can provide information on the frequency- and aspect dependent scattering in a scene. We suggest an approach to predict the quality of the sensor data over the available frequencies and aspect angles. We relate the typical spatial domain quality metrics to their wave number domain (WD)...article 2017
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Moreau, L. (author), Hunter, A.J. (author), Velichko, A. (author), Wilcox, P.D. (author)In nondestructive testing, being able to remotely locate and size defects with good accuracy is an important requirement in many industrial sectors, such as the petrochemical, nuclear, and aerospace industries. The potential of ultrasonic guided waves is well known for this type of problem, but interpreting the measured data and extracting...article 2014
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Giodini, S. (author), Hunter, A.J. (author), Naus, H.W.L. (author), Bakker, B. (author), Bekers, D.J. (author), Ditzel, M. (author), van Vossen, R. (author), Dugelay, S. (author), Baralli, F. (author), Beckers, A.L.D. (author)Minehunting operations can benefit from the use of Autonomous Underwater Vehicles (AUVs) because these vehicles are able to acquire high-resolution images of the seabed leaving the man out of the minefield. However, because there are severe communication constraints between the AUV and the control platform, the AUV needs to be capable of...conference paper 2014
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Hunter, A.J. (author), van Vossen, R. (author)Background reverberation can obscure useful features of the target echo response in broadband low-frequency sonar images, adversely affecting detection and classification performance. This paper describes a resolution and phase-preserving means of separating the target response from the background reverberation noise using a coherence-based...article 2014
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Fillinger, L. (author), Hunter, A.J. (author), Clarijs, M.C. (author)Since 2010, TNO has conducted a number of experiments on passive diver detection in Dutch waters. We have demonstrated detection, localization and tracking of divers wearing open circuit and closed circuit underwater breathing apparatus as well as boats. However, until now, we have not conducted any such experiments in warm waters. The...conference paper 2014
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van Vossen, R. (author), Giodini, S. (author), Hunter, A.J. (author), Beckers, A.L.D. (author), Williams, D.F. (author)The effectiveness and efficiency of mine-hunting operations with autonomous underwater vehicles (AUVs) are greatly influenced by environmental conditions, such as seabed, turbidity, currents, and tides. Therefore accurate environmental information is needed for the planning and evaluation of mine-hunting operations. Because environmental...conference paper 2013
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Fillinger, L. (author), Hunter, A.J. (author), Zampolli, M. (author), Clarijs, M.C. (author)Divers, including closed circuit (rebreather) divers constitute a potential threat to waterside infrastructures. Active diver detection sonars are available commercially but present some shortcomings, particularly in highly reverberant environments. This has led to research on passive sonar for diver detection. Passive detection of open-circuit...conference paper 2013
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Hunter, A.J. (author), van Vossen, R. (author), Quesson, B.A.J. (author), Beckers, A.L.D. (author)The remediation of underwater unexploded ordnance (UXO) requires a capability to detect and classify objects on or beneath the seafloor. This can be facilitated partly by use of modern high-frequency imaging sonar. However, this technology is limited in two respects: 1) the high frequencies employed by these systems cannot penetrate into the...conference paper 2013
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Hunter, A.J. (author), Fillinger, L. (author), Clarijs, M.C. (author)A boom is a line of floats that constitutes a physical barrier for providing abovewater stopping power. However, it does not provide any situation awareness. In order to overcome this shortcoming, an integrated “booms and sensors” solution using passive sonar was conceived and tested experimentally by suspending hydrophones under a boom. The...conference paper 2013
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Hunter, A.J. (author), van Vossen, R. (author)A method is presented for separating the broadband acoustic target response from the background seafloor reverberation based on the multi-look synthetic aperture sonar (SAS) image coherence. The method computes the coherence in the wavelet domain and uses this to distinguish between the target and background, which are assumed to be...conference paper 2013
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Hayes, M.P. (author), Hunter, A.J. (author)Synthetic aperture side-scan sonar (SAS) is a mature technology for high-resolution sea floor imaging [1]. Interferometric synthetic aperture sonars (InSAS) use additional hydrophones in a vertical array for bathymetric mapping [2]. This has created high-resolution bathymetry in deep water environments [3] but results in shallow water have been...conference paper 2012
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van Vossen, R. (author), Quesson, B.A.J. (author), Beckers, A.L.D. (author), Zampolli, M. (author), Colin, M.E.G.D. (author), Hunter, A.J. (author)Naval mines, underwater improvised explosive devices (UW-IEDs), and underwater unexploded ordnance (UW-UXO) are concerns for harbour security. In conditions without burial, existing commercial systems, such as the REMUS unmanned underwater vehicle equipped with a (very) high frequency side scan sonar (900/1800 kHz), may be deployed for detection...conference paper 2012
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Hunter, A.J. (author), Fillinger, L. (author), Zampolli, M. (author), Clarijs, M.C. (author)A PHD particle filter implementation has been detailed for the fusion of measurements from multiple passive sonar nodes. It has been demonstrated on simulated metadata and on experimental passive acoustic data of divers and small boats collected in an operational port environment. Fusion at the metadata level lowers the necessary data bandwidth,...conference paper 2012
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Hunter, A.J. (author), Fillinger, L. (author), Zampolli, M. (author), Clarijs, M.C. (author)Surveillance of waterside locations for protection against threats from small fast surface vessels and underwater intruders is a very relevant but challenging problem. For this reason, the Netherlands Organisation for Applied Scientific Research (TNO) is developing SOBEK – a family of passive sonar technologies for waterside surveillance. The...conference paper 2012
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Hunter, A.J. (author), van Vossen, R. (author), Quesson, B.A.J. (author), Colin, M.E.G.D. (author), Zampolli, M. (author), Beckers, A.L.D. (author)Sidescan high-frequency (HF) sonar (i.e., with frequencies higher than 100 kHz) is ideally suited for providing high-resolution images of the seafloor. However, since sound does not penetrate into the sediment at these frequencies, such systems cannot be used for the detection of buried objects, such as naval mines, improvised explosive devices ...conference paper 2012
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Hayes, M. (author), Hunter, A.J. (author)Bathymetric estimation from multiple synthetic aperture sonar (SAS) images is challenging for shallow water environments with low frequencies. This is due to the multipath echoes corrupting the desired direct-path echoes. In an attempt to suppress some of these multipaths, the MUD synthetic aperture sonar developed at TNO has a sixteen element...conference paper 2012
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Zhang, J. (author), Drinkwater, B.W. (author), Wilcox, P.D. (author), Hunter, A.J. (author)The quality of an ultrasonic array image, especially for anisotropic material, depends on accurate information about acoustic properties. Inaccuracy of acoustic properties causes image degradation, e.g., blurring, errors in locating of reflectors and introduction of artifacts. In this paper, for an anisotropic austenitic steel weld, an autofocus...conference paper 2012
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Fillinger, L. (author), Hunter, A.J. (author), Zampolli, M. (author), Clarijs, M.C. (author)Divers constitute a potential threat to waterside infrastructures. Active diver detection sonars are available commercially but present some shortcomings, particularly in highly reverberant environments. This has led to research on passive sonar for diver detection. Passive detection of open-circuit UBA (underwater breathing apparatus) has been...article 2012
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Volker, A.W.F. (author), Vos, H.J. (author), Hunter, A.J. (author), Lorenz, M. (author)The inspection of wall loss corrosion is difficult at pipe support locations due to limited accessibility. However, the recently developed ultrasonic Multi-Skip screening technique is suitable for this problem. The method employs ultrasonic transducers in a pitch-catch geometry positioned on opposite sides of the pipe support. Shear waves are...conference paper 2012
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Volker, A.W.F. (author), Vos, H.J. (author), Hunter, A.J. (author)The inspection of wall loss corrosion is difficult at pipe support locations due to limited accessibility. However, the recently developed ultrasonic Multi-Skip screening technique is suitable for this problem. The method employs ultrasonic transducers in a pitch-catch geometry positioned on opposite sides of the pipe support. Shear waves are...conference paper 2012
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