Accession Number:

ADA056615

Title:

Vertical Spatial Correlation of Reverberation in Shallow Water - Mode Enhancement Techniques (METS) as a Means to Improve Echo Detection.

Descriptive Note:

Technical rept.,

Corporate Author:

NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CONN NEW LONDON LAB

Personal Author(s):

• King,Louis A.
• Bachor,Wolfgang
• Carone,Ralph W.

Report Date:

1978-05-24

Pagination or Media Count:

22.0

Abstract:

A vertical array of transducers, amplitude shaded with uniform and cosine weightings, and two of its individual elements were used to produce reverberation at 1700 Hz under iso-sound speed conditions in waters 30 m deep. Eleven of the vertical array elements spaced 1 m apart were than used to receive and record the reverberation levels as a function of range time. The vertical correlation values of reverberation as a function of hydrophone spacing for the transmitting configurations were obtained using a clipper correlator. Although the uniform and cosine configurations produced higher correlation values than did the single transducers, they fell below 0.5 for spacings greater than 2 m. By assuming echoes that consist primarily of mode 1 or mode 2 and applying Mode Enhancement Techniques METS to a receiving array of six elements uniformly spaced 2 m apart, we see that the array gain is computed to be 3.0 and 7.8 dB, repsectively. The example of METS indicates that appreciable array gains can be achieved with vertical arrays operating in shallow water. Author

Descriptors:

• *SHALLOW WATER
• *REVERBERATION
• *ECHO RANGING
• SIGNAL TO NOISE RATIO
• ACOUSTIC ARRAYS
• HYDROPHONES
• SOUND PRESSURE
• SONAR TRANSDUCERS
• UNDERWATER SOUND SIGNALS
• SONAR ARRAYS

Subject Categories:

• Acoustic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE