Accession Number:

ADA551664

Title:

Time-Reversing Array Focusing in Shallow Ocean Waters

Descriptive Note:

Annual rept.

Corporate Author:

MICHIGAN UNIV ANN ARBOR DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS

Personal Author(s):

• Dowling, David R.

Report Date:

1998-01-01

Pagination or Media Count:

5.0

Abstract:

The long-term goals of this project are as follows 1 to predict and understand time reversing array TRA retrofocus size and longevity in a shallow water acoustic environment based on acoustic, geometrical, and environmental parameters and 2 to deduce the effectiveness of using a TRA for monitoring andor determining the acoustic properties of unknown environments. The specific goals of this project are to determine TRA retrofocus size and longevity in the presence of a linear superposition of dynamic random shallow water internal waves, noise, and three dimensional effects typical of the shallow ocean. In particular, the influence of acoustic frequency, source array range, and propagation in a dynamic mulitpath sound-channel on time-reversing array retrofocusing is not completely understood. The challenge here is to separate the various influences and impacts of propagation complexities bottom losses, water-column dynamics, noise, three-dimensional scattering, etc. so that the phenomena primarily responsible for TRA retrofocusing persistence and limitations can be identified. While our past work dealt with simple dynamic environments, the current effort incorporates realistic oceanic sound propagation to a much greater degree.

Descriptors:

• *ACOUSTIC CHANNELS
• *INTERNAL WAVES
• *OCEAN ENVIRONMENTS
• *SHALLOW WATER
• *SONAR ARRAYS
• *SONAR SIGNALS
• *SOUND TRANSMISSION
• *WHITE NOISE
• ACOUSTIC SCATTERING
• ACOUSTIC VELOCITY
• PERFORMANCE(ENGINEERING)
• SIGNAL PROCESSING
• WATER CHANNEL TEST FACILITIES

Subject Categories:

• Physical and Dynamic Oceanography
• Acoustic Detection and Detectors
• Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE