Model analysis of energy spreading loss off the Carolina Coast for tactical active sonars

Download
Author
Smith, Peter E.
Date
1998-03-01Advisor
Bourke, Robert H.
Wilson, James H.
Metadata
Show full item recordAbstract
Energy spreading loss (ESL) is the reduction of the transmitted pulse energy level by spreading of the pulse in time due to multipath propagation. This energy spreading will reduce the effectiveness of mid-frequency tactical sonars. The U.S. Navy training areas of Long Bay and Onslow Bay off the Carolina Coast were chosen for the study of ESL to provide contrasts in many of the geoacoustic properties that can change ESL. Inputs were varied by source depth, receiver depth, sound speed profile(SSP), bathymetry, and geoacoustic properties. The computer model FEPE_SYN calculated the ocean transfer function (OTF) for the modeled environment in the frequency domain. The time domain output pulse was calculated using the OTF, an input pulse, and an inverse discrete Fourier transform. Using the same energy as the output pulse, a compressed pulse was created with the same shape as the input pulse. ESL was determined by comparing the peak level of the output pulse to the peak level of the compressed pulse. A mismatch loss (MML) was calculated by comparing the maximum values from the correlation of the input pulse with the output pulse and compressed pulse. The ESL of the output pulse was dependent on several factors. Absorptive (silt/clay) sediment sea beds had average ESL values 3 dB less than that of compacted sand. The compacted sand bottom was also compared to an even more reflective sediment, a limestone sediment layer. ESL values were higher by an additional 3 dB for the limestone bottom. Minimum ESL levels were found when the source and target were at the same depth. Changing source and target depths (e.g., cross layer) could increase ESL levels up to 8 dB from the minimum ESL level. The impact of using a range-dependent SSP vice constant SSP was inconclusive in that ESL values could be larger or smaller by 3 dB compared to range-independent runs. Similar inconclusive results were obtained when actual bottom depths were employed vice a flat-bottom run.
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.Collections
Related items
Showing items related by title, author, creator and subject.
-
An analysis of energy spreading loss associated with tactical active sonar performance in a shallow water environment.
Tanaka, Akira (Monterey, California. Naval Postgraduate School, 1996-06);Energy spreading loss (ESL) is qualitatively defined as the reduction in peak echo level due to energy spreading of the transmitted acoustic pulse in time. An analysis of the impact of shallow water propagation on ESL was ... -
AIR MOTOR INTEGRATION FOR A SMALL-SCALE COMPRESSED AIR ENERGY STORAGE SYSTEM
McMahan, John D. (Monterey, CA; Naval Postgraduate School, 2021-06);The lack of on-demand energy production capabilities, paired with the lack of sufficient battery technology, has been a major issue for renewable energy source viability. Compressed Air Energy Storage (CAES) offers the ... -
An assessment of hydrogen as a means to implement the United States Navy's renewable energy initiative
Paradis, Jason D. (Monterey, California: Naval Postgraduate School, 2014-09);In response to Presidential Executive Order 13514, the Secretary of the Navy established the 1GW Task Force to meet theNavy's goal of producing at least half of shore-based energy requirements from alternative energy ...