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Shallow-water seafloor characterization for high-frequency multibeam echosounder: image segmentation using angular backscatter
(NATO. SACLANTCEN, 1997)
Sonar images from multibeam echosounders are submitted to various degradations, partly due to the sensor itself: Signal artefacts and corresponding corrections are presented, both for signal processing and for array ...
Swath bathymetry and SAS autofocus using a Chirp source
(NATO. SACLANTCEN, 1997)
Swath bathymetry and SAS autofocus can both be treated as problems in correlating echoes from a scatterer distribution on the seabed. Using a chirp source, the phase derived from quadrature match-filtering can replace the ...
Bayesian inference and sidescan restoration
(NATO. SACLANTCEN, 1997)
We consider a Bayesian approach to the problem of inferring parameters of the SONAR environment given only the gathered sidescan image. A simplified model of the process is developed along with suitable distributions on ...
A high frequency approach for seabed vegetation characterization
(NATO. SACLANTCEN, 1997)
This paper focuses on the characterization of seabed vegetation, an interesting problem in a lot of Mediterranean sea coastal sites since water quality and pollution degree can be efficaciously solved by investigating the ...
Interactive tools for the exploration and analysis of multibeam and other seafloor acoustic data
(NATO. SACLANTCEN, 1997)
The Ocean Mapping Group has developed a full suite of software tools for the real-time or near real-time display, editing, quality control, interpretation and visualization of multibeam sonar data. The combination of ...
A new ambient noise imaging system for ANI, passive and bistatic active acoustic imaging in shallow water
(NATO. SACLANTCEN, 1997)
Shallow water active and passive sonars can be usefully complimented by broadband Ambient Noise Imaging (ANI) systems. The first AN1 system was largely analogue, produced good images at 38 m range, but was bulky and permitted ...
Wavelet analysis of side scan sonar imagery for classification
(NATO. SACLANTCEN, 1997)
Wavelet-based techniques are presented for compressing side scan sonar images communicated from UUV's through band limited communication channels. Testing with an automatrc classifier on reconstructed images demonstrates ...
Estimating surface orientation from sonar images
(NATO. SACLANTCEN, 1997)
A maximum likelihood method for estimating remote surface orientation from multi-static sonar images is presented. It is assumed that the sonar images are corrupted by signal-dependent noise, known as speckle, arising from ...
Analysis and problems of HF acoustic coherent and incoherent simulations in shallow water
(NATO. SACLANTCEN, 1997)
Shallow water environments create complex scattering condit~ons due to the sea surface and bottom scattering mechanisms. An analysis of the effects of the scattering mechan~smso n sonar images of simple targets in shallow ...
Very-high (cm scale) resolution multichannel seismology
(NATO. SACLANTCEN, 1997)