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The technology being developed also has broad application to 

 industry requirements to map geophysical properties of the sediment for 

 pipeline routing and detection/localization. In addition, some components 

 of this technology have broader applicability than just mapping the ocean 

 bottom. For example, the visualization technology for map and chart data 

 as seen from a continuously moving platform is already in use in Navy 

 aircraft, enabling pilots to continuously know exactly where they are. NRL 

 is currently discussing this technology with the Department of 

 Transportation to determine its applicability to some of their 

 requirements. 



ACOUSTIC SEAFLOOR CLASSIFICATION SYSTEM 



The CNR has worked to develop acoustic systems which sample the 

 ocean bottom and subbottom to improve our understanding of the 

 geological processes responsible for the observed structure and physical 

 properties. These properties are of fundamental importance to such Navy 

 missions as mine warfare and mine counter measures (MIW, MCM), shore 

 side facilities construction, and anti-submarine warfare (ASW). 



One particular system with potential civilian use for mapping and 

 charting applications is NRL's Acoustic Seafloor Classification System 

 (ASCS). The ASCS is normally operated at 15 kHz, and both quantitatively 

 and qualitatively measures the amplitude (echo strength) and pulse 

 character of the returned acoustic signal in 10 adjustable width-time 

 windows that correspond to depth increments in the sediment. Using 

 appropriate signal processing of the returned signal and the use of known 

 empirical relationships, the ASCS produces a continuous profile of 

 predicted sediment structure and type, as well as various geotechnical 

 properties of the sediment, such as attenuation, density, porosity, shear 

 strength, compressional and shear velocity, and mean grain size. 



Another system is the ONR-sponsored chirp sonar which is a towed, 

 digital, frequency-modulated (FM), subbottom profiler that produces high 

 resolution images of ocean sediments. The system transmits computer- 

 generated FM pulses that sweep over an area. The FM signal can cover a 

 range of frequencies from 200 Hz to 30 kHz and resolve sediment layers 

 as close as 5 cm apart. This technology has been transitioned to U.S. 

 industry which is marketing it in the U.S., Japan and Europe. 



