Acoustic propagation loss modeling for Dabob Bay, Wa.

74 Pages·0.68 MB·en_US

by  Mitchell, John R.;Wilson, O. B.

NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
ACOUSTIC PROPAGATION LOSS MODELING
FOR DABOB BAY, WA
by
John R. Mitchell
September, 1991
Thesis Advisor: 0. B. Wilson, Jr.
Approved for public release; distribution is unlimited.

Unclassified
SECURITYCLASSIFICATIONOFTHIS PAGE
REPORT DOCUMENTATION PAGE
UNCLASSIFIED
a Report Security Classification 1b Restrictive Markings
2a Security Classification Authority 3 Distribution Availability of Report
2b Declassification/Downgrading Schedule Approved for public release; distribution is unlimited
4 Performing Organization Report Number(s) 5 Monitoring Organization Report Number(s)
6a Name of Performing Organization 6b Office Symbol 7a Name of Monitoring Organization
Naval Postgraduate School (IfApplicable) 3A Naval Postgraduate School
6c Address (city, state, and ZIP code) 7b Address (city, state, and ZIP code)
Monterey, CA 93943-5000 Monterey, CA 93943-5000
8a Name of Funding/Sponsoring Organization 8b Office Symbol 9 Procurement Instrument Identification Number
(7/ Applicable)
8c Address (city, state, and ZIP code) 10 Source of Funding Numbers
V
ProgramElementNumber | ProWjecAtNo TaskNo WorkUnitAccession
1 1 Title (Include Security Classification) Acoustic Propagation Loss Modeling For Dabob Bay.
12 Personal Author(s) Mitchell, John R
13a Type of Report 13b Time Covered 14 Date of Report (year, month, day) 15 Page Count
Master's Thesis From To September 1991
16 SupplementaryNotation The views expressed in this thesis are those ofthe author and do not reflect the official
policy or position ofthe Department ofDefense or the U.S. Government.
17 Cosati Codes 18 Subject Terms (continue on reverse ifnecessary and identiWfyAby block number)
Field Group Subgroup Acoustic Propagation Loss Modeling, Dabob Bay,
I
19 Abstract (continue on reverse ifnecessary and identify by block number)
An analysis ofthe acoustic sound propagation in a multipath environment in an ocean at short ranges has been
conducted using a Modified Time Delay Spectrometry (TDS) and an experimental continuous-wave technique.
WA
Data from the acoustic range at Dabob Bay, were analyzed to determine the relative amplitudes ofthe direct-
and surface-reflected signals. The results show that, at moderate ranges and typical source and receiver depths,
the surface-reflected sound is a significant contributor to the received sound level. The theory supporting both
techniques is presented. Discussions and conclusions are drawn. Recommendations for future investigation are
made.
20 Distribution/Availability of Abstract 21 Abstract Security Classification
X| unclassified/unlimited same as report DTTCusers Unclassified
| J
22a Name of Responsible Individual 22b Telephone (IncludeArea code) 22c Office Symbol
Prof. O. B. Wilson , Jr. [phone] PH/W1
DD FORM 1473, JUN 86 Previous editions are obsolete. SFCURrTYCLASSIFICATIONOFTHIS PAGE
S/N 0102-LF-014-6603 Unclassified
Approved for public release; distribution is unlimited.
Acoustic Propagation Loss Modeling
For Dabob Bay, Wa.
by
John R. Mitchell
Lieutenant, United States Navy
B.S., Clemson University
Submitted in partial fulfillment
of the requirements for the degree of
MASTER OF SCIENCE IN APPLIED SCIENCE
from the
NAVAL POSTGRADUATE SCHOOL
September 1991
ABSTRACT
An analysis of the acoustic sound propagation in a multipath environment in an
ocean at short ranges has been conducted using a Modified Time Delay Spectrometry
(TDS) and an experimental continuous-wave technique. Data from the acoustic test range
WA
at Dabob Bay, were analyzed to determine the relative amplitudes of the direct- and
surface-reflected signals. The results show that, at moderate ranges and typical source
and receiver depths, the surface-reflected sound is a significant contributor to the
received sound level. The theory supporting both techniques is presented. Discussions
and conclusions are drawn. Recommendations for future investigation are made.
...
111
.
n
TABLE OF CONTENTS
INTRODUCTION
I. 1
A. Background
1
B. Objective 2
MULTIPATH PROBLEM DESCRIPTION
II. 4
A. The Multipath Problem 4
B. Assumptions 4
C. Multipath Geometry 5
MEASUREMENT TECHNIQUES
III. 8
A. TDS Technique 8
1 The Excitation Signal 8
2. Dynamic Signal Analyzer Operation 10
B. Continuous-Wave Method 12
MULTIPATH MEASUREMENT SYSTEM
IV. 14
A. Test Configuration 14
B. Data Processing System 17
IV