Thin line array for littoral ASW

Automatic target recognition in synthetic aperture sonar images for autonomous mine hunting

The future of Mine Countermeasures (MCM) operations lies with unmanned platforms where Automatic Target Recognition (ATR) is an essential step in making the mine hunting process autonomous. At TNO, a new ATR method is currently being developed for use on an Autonomous Underwater Vehicle (AUV), using SAS images of known targets in an operational...

On the Detection of Drifting Sea Mines using Above- and Underwater Sensors

Small drifting objects can be a big threat to surface ships, especially when the objects are explosion hazards like sea mines that have become detached from their moorings. Timely detection of such objects is crucial in order to be able to perform adequate evasive manoeuvres. However, the vertical position of drifting mines is a serious...

Shadow Enhancement in Synthetic Aperture Sonar Using Fixed Focusing

Abstract—A shadow cast by an object on the seafloor is important information for target recognition in synthetic aperture sonar (SAS) images. Synthetic aperture imaging causes a fundamental limitation to shadow clarity because the illuminator is moved during the data collection. This leads to a blend of echo and shadow, or geometrical fill-in in...

Long range echo classification for minehunting sonars

This paper focesus on single-ping classification of sea mines, at a range of about 400 m, and combining a hull mounted sonar (HMS) and a propelled variable-depth sonar (PDVS). The deleoped classifier is trained and tested on a set of simulated realistic echoes of mines and non-mines. As the mines ate too far away for image-based classification,...

Validation of high frequency acoustic target modeling

The underwater acoustics group at TNO Defense, Security and Safety has developed two simulation software programs named ALMOST and SIMONA. The first is already commercially used and aims at sonar performance prediction, whereas the second one is used as a tool to generate simulated data for mine hunting scenarios with the aim to test different...

Simulation of high resolution mine hunting sonar measurements

An acoustic simulator is vital for the development of sonar data processing. The most important features in the TNO 3D simulator SIMONA are detailed target response including shadow, reverberation modelling, sonar properties and multipath. The verification and development of SIMONA was realized alongside with a wide range of measurements in a...

Shadow enhancement in synthetic aperture sonar imagery for improved target classification

The acoustic shadow of a target is a strong classification clue in naval mine hunting. A shadow of bottom targets appears at relatively short ranges (≤ about 200 m) in high resolution images from sidescan or synthetic aperture sonar (SAS), against a background of sea floor reverberation. In SAS however, definition of the shadow reduces with...

Experiments with a Ship-Mounted Low Frequency SAS for the Detection of Buried Objects

In September 2002, GESMA and TNO-FEL carried out a sea trial with a low frequency (20 kHz) sonar mounted on a mine hunter. The objective of the experiments was to collect sonar echoes from proud and buried objects for subsequent synthetic aperture processing. A large data set was collected, consisting of sonar data from several SAS modes and...

SAS Processing Results for the Detection of Buried Objects with a Ship-Mounted Sonar

In September 2002, TNO-FEL and GESMA carried out a sea experiment with a low frequency (20 kHz) sonar mounted on a mine hunter. To our knowledge, it is the first time the synthetic aperture sonar technique has been implemented on board an operational mine hunter for the purpose of buried mines detection. The collected data set is mainly made up...

Sonar path correction in synthetic aperture processing

In the next generation of mine hunting sonars, in particular on Autonomous Underwater Vehicles (AUVs), Synthetic Aperture Sonar (SAS) will play an important role. The benefit of SAS is to increase resolution and signal-tonoise ratio by coherent processing of successive pings. A challenge in SAS is the computational load. This is caused primarily...

Choice for the signal processing kernel in synthetic aperture sonar: Considerations and implications

Synthetic Aperture Sonar uses coherent integration of successive pings to enhance the resolution of side looking sonar. In this paper three diffelent SAS methods are applied to obtain high-resolution images. The first method is applied ping by ping in the frequency domain, whereas the second and third method are applied in the wavenumber...

Interaction between autofocusing and synthetic aperture processing: A study based on simulations and experimental rail data

Array Focusing for Buried Object Detection and Identification

Marker-referred movement measurement with grey-scale coordinate extraction for high-resolution real-time 3D at 100 Hz

A review of early history in photography highlights the origin of cinefilm as a scientific tool for image-based measurement of human and animal motion. The paper is concerned with scanned-area video sensors (CCD) and a computer interface for the real-time, high-resolution extraction of image coordinates of moving markers. Algorithms and...