Accession Number : AD0731361

Title :   Volume Reverberation Studies with Deep Research Vehicle Deepstar 4000.

Descriptive Note : Research rept.,

Corporate Author : NAVAL UNDERWATER SYSTEMS CENTER NEWPORT R I

Personal Author(s) : Dullea,Robert K. ; Fisch,Norbert P.

Report Date : 30 APR 1971

Pagination or Media Count : 23

Abstract : From July to October 1967, reverberation caused by the Deep Scattering Layers (DSL) was measured from the DRV deepstar 4000 in the Gulf of Mexico and on the continental rise from Florida to Nova Scotia. A narrow-beam, transducer-reflector system operating between 3.25 and 4.75 kHz was employed at several depths to make horizontal transmissions with pulse lengths of 40 and 120 msec, while graphic records of the depth of the DSL were obtained concurrently onboard the support ship. Daytime scattering strengths were at a noise threshold of -80 dB, except at one northern station where -70 dB was found. Maximum nighttime values of scattering strength of -55 dB were observed east of Delaware with decreases in magnitude both north and south of this location. East of Cape May, results obtained 1 year earlier with DRV STAR III were confirmed. Nighttime reverberation was attributed to scatterers between the surface and a depth of 300 m. Also, no measurable frequency dependence in scattering strength was noted in the range from 3.25 to 4.75 kHz. (Author)

Descriptors :   (*UNDERWATER SOUND, BACKSCATTERING), SOUND TRANSMISSION, SCATTERING, UNDERWATER VEHICLES, DEEP SUBMERGENCE, TRANSDUCERS, DIURNAL VARIATIONS, ECHO RANGING, MARINE BIOLOGICAL NOISE, SONAR SIGNALS, CONTINENTAL SHELVES, MEXICO GULF, ATLANTIC OCEAN

Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE