A study of underwater sound ray tracing methodology
By: Robert R. Read
Contributors: Naval Postgraduate School (U.S.). Dept. of Operations Research
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1990
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 97
Subjects: ACOUSTIC TRACKING; RAY TRACING; UNDERWATER TRACKING
Other titles: NPS-55-90-21.
Description: An operational study has been made of algorithms employed in short base line underwater      position location systems. Some important sources of systematic error have been uncovered.      The issues studied include isospeed vs. isogradient ray tracing, effect of the depth velocity      profile and water layer thickness, approximate vs. exact array tilt corrections, and ray tracing      initialization methodology. It is shown that the practice of constant speed extrapolation of      depth-velocity information can cause considerable mischief. The best remedy is to measure      speed all the way to the bottom. It is further shown that the systematic errors are periodic      functions of the azimuth direction of the sound ray from the receiver array. The amplitudes of      these functions are greater for the more severely tilted arrays. An alternative algorithm is      proposed that reduces these errors by at least an order of magnitude. Keywords: Ray      tracing; Calibration; Underwater tracking; Short baseline systems; Systematic errors. (JHD)
Notes: Cover title.

"NPS-55-90-21."

"September 1990."

AD A229 666.

Includes bibliographical references (p. 93).

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