Sub-bottom profiling with ambient noise measured on a drifting vertical array

The angle and frequency dependent reflective properties of the seabed can be determined from beam-steered ambient noise measurements on a vertical array of hydrophones. From the up-to-down ratio the beam-smeared modulus square of the plane wave reflection coefficient is obtained. Geo-acoustic parameters can be inverted by matching the measured...

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...

Validation of the propagation, target echo and sonar performance model ALMOST with near field target echo measurements

Since the late eighties the sonar performance model ALMOST of TNO Defence, Security and Safety is under development. For active detection performance first a point target with one Target Strength (TS) value dependent on aspect angle was used, based on measurements or other sources. Within the Torpedo Defence System Test Bed (TDSTB), developed at...

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...