Publication:
A study of underwater sound ray tracing methodology

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Authors
Read, Robert R.
Subjects
Ray tracing
Calibration
Underwater tracking
Short baseline systems
Systematic errors
Advisors
Date of Issue
1990-09
Date
1990-09
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
An operational study has been made of the algorithms employed by the Naval Undersea Weapons Engineering Aviation in their short base line underwater position location systems. Some important sources of systematic error have been uncovered. The issues stuided 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...
Type
Technical Report
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)
Series/Report No
Department
Identifiers
NPS Report Number
NPS55-90-21
Sponsors
This report was prepared under the joint support of Naval Undersea Warfare Engineering Station, Keyport, Washington and the Naval Postgraduate School Research Program
Funder
Format
i, 97 p. : ill. ; 28 cm.
Citation
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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