00000nam 2200000zi 4500 9.943035 CaOODSP 20240919150927 m o d f cr bn||||||||| 240909e198906##nscd ob f000 0 eng d CaOODSP eng rda CaOODSP eng eng fre n-cn-ns ln----- D68-21/25-1989E-PDF Staal, Philip Ralph, author. Propagation-loss measurements and modelling for topographically smooth and rough seabeds / Philip R. Staal - Francine Desharnais ; approved by R. S. Walker. [Dartmouth, N.S.] : National Defence, Research and Development Branch, Defence Research Establishment Atlantic, June 1989. 1 online resource (v, 34 pages) : graphs. text txt rdacontent computer c rdamedia online resource cr rdacarrier Technical memorandum ; 89/214 Cover title. Digitized edition from print [produced by Defence Research and Development Canada]. Includes bibliographical references (pages 30-31). "Acoustic propagation loss data were obtained along two radial tracks from a receiving array at a site on the Scotian Shelf. One track was over a smooth seabed and the other over a rough seabed. The features of the propagation loss data for the two seabed types have been analyzed and compared. At-sea measurements show that fluctuations in the propagation loss data are correlated with water-depth variations for the case of the rough seabed. Two different propagation-loss modelling programs are used in an attempt to explain the acoustic features observed over the two seabeds. The majority of the modelled results were obtained with PROLOS, a DREA-developed range-dependent normal-mode program. The results of a ray-trace propagation loss model (GRASS) are also compared with the measured data. The ray-trace model provides insight on which acoustic transmission paths are most important, while PROLOS is able to model the propagation-loss over both the smooth and rough seabeds surprisingly well"--Abstract, page ii. Includes abstracts in English and French. Underwater acoustics Scotian Shelf Measurement. Submarine topography Scotian Shelf. Acoustique sous-marine Néo-écossaise, Plateforme Mesure. Topographie sous-marine Néo-écossaise, Plateforme. Defence Research Establishment Atlantic, issuing body. D.R.E.A. technical memorandum ; 89/214. (CaOODSP)9.941838 PDF 363 KB https://publications.gc.ca/collections/collection_2024/rddc-drdc/D68-21-25-1989-eng.pdf