Accession Number : ADA115298

Title :   Navigation Hazard Survey Sonar.

Descriptive Note : Technical note,

Corporate Author : NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY NSTL STATION MS

Personal Author(s) : Moss,George J , Jr

PDF Url : ADA115298

Report Date : Apr 1982

Pagination or Media Count : 57

Abstract : A towed side-scan sonar with a 2 nautical mile (NM) range would permit a hydrographic survey ship to sweep a 4nm swath for navigation hazards. The increased track spacing made possible by such a system would result in substantial savings in ship time. A conical, rather than a fan-shaped, beam would be required in coastal waters because of the proximity of the ocean surface and floor relative to the sonar range. For isovelocity water with sufficient wave height to make insonification of the surface undesirable, a 2.5 deg. beam would be required for a 2 nm range in 80 meter (m) deep water, or for a 1 nm range in 50 m deep water. The water depth required under refracting conditions depends on the mixed layer sound speed gradient and the surface wave height. Nonlinear acoustics can be used to generate the required narrow beams at frequencies compatible with the 2 nm range without the use of excessively large projectors. (Author)

Descriptors :   *Towed sonar, Side looking sonar, Surface navigation, Hazards, Underwater, Detection, Shallow water, Coastal regions, Acoustic beams, Narrow beams(Radiation), Radiation patterns, Underwater sound generators, Nonlinear systems, Ray tracing, Hydrographic surveying

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE