For years, sidescan sonars have been used to map the seabed and detect small targets. However, a shortcoming of conventional systems has been the inability to collect acoustic data digitally. By collecting data digitally, navigation data may be coupled with acoustic information to provide the precise position and size of objects on the seabed. Advanced image and signal-processing tools may be applied to improve the information in the displayed and stored image to take advantage of the true resolution of the sidescan sonar.
EOSCAN™ is a next-generation sonar data acquisition, processing and display system. It con-nects to any analogue or digital sidescan sonar, providing a robust yet economical side-scan bathymetric and sub-bottom profiler processing tool utilising powerful DSP technology. EOSCAN collects high-quality sonar imagery digitally merged with navigation onto optical disk. It also logs targets, sizes, heights, LAT/LON and user-defined descriptors to local or remote disk. Its portable system can be mobilised onto a wide variety of ocean craft and its straightfor-ward user interface provides powerful options and selections requiring a minimal amount of training.
| Below: Screen dump of the Eoscan sonar data aquisition, display and processing system. Inserts: images from automatically logged targets |
The system offers time savings on data processing, interpretation and report genera-tion and it reduces or eliminates costly onshore post-processing. EOSCAN's high-quality images may be created, processed and displayed from pre-existing tape-recorded or digital data. It enables report generation and decision making to take place in the field.
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EOSCAN provides real-time target analysis and logging software. During the real-time scrolling display of bathymetry and sonar imagery, users can determine the position of any target on the screen as all pixels in the image are geocoded in real time. By simply pressing the left trackball button, the target is magnified, based on a user-specified zoom factor and final size. By using the right mouse button, users can measure the plan-view dimensions of a target and, if an acoustic shadow is found behind the target, they also can measure the altitude of the target above the bottom. If users elect to log the target, they press a key and a menu of user-defined target descriptors pops up for selection. Should users pick a descriptor, the descriptor as well as a full range of other information regarding the target is logged to a file. In addition, the system automatically stores a PCX target file snippet to EOSCAN disk or over an Ethernet link to a separate UNIX-based platform.
Target detection is made easier with the auto-mated target detection assistant (TDA) and real-time target replay. The EOSCAN TDA detects targets of a user-defined size and sonar charac-teristic. Users can create an on-line library of targets or provide search descriptors for EOSCAN. Target replay allows for replay of previous passes over the same target or other targets of similar shape and size.
