An analysis of the effects of energy spreading loss and transmission loss on low frequency active sonar operations in shallow water
Adams, Brian S.
Robert H. Bourke
James H. Wilson
MetadataShow full item record
Energy Spreading Loss (ESL) is qualitatively defined as the reduction in peak power level due to energy spreading of a transmitted acoustic pulse in tune. An analysis of the impact of bathymetric geometry and sediment type on ESL and TL associated with the Low Frequency Active/Compact Low Frequency Active (LFA/CLFA) sonar operations was conducted utilizing the FEPE, FEPE_SYN and EXT_TD programs to model the time spreading of the acoustic pulse due to multipath propagation in shallow water. Both a Blackman windowed pulse and a Continuous Wave (CW) pulse were used in this analysis. The Blackman pulse had a center frequency of 244 Hz with a bandwidth of 24 Hz. The CW pulse had a center frequency of 244 Hz with a bandwidth of 0.0625 Hz. Model inputs were a geoacoustic description of the Tanner Bank region off the coast of San Diego and a typical late summer sound speed profile taken from the MOODS database. ESL and TL's impact on low frequency active sonar operations was determined as a function of bathymetry, sediment type, sound speed profile, and pulse length. The results showed that ESL is inversely related to pulse duration and at low frequencies is relatively uninfluenced by sediment type. When pulse lengths were reduced to less than 1 second, ESL became appreciable ( > 6 dB one way) and was an important segment of the active sonar equation. TL was found to be the dominating factor in LFA/CLFA operations for pulse lengths greater than 1 second and was greatly influenced by sediment type and sound speed profile.
Approved for public release; distribution is unlimited
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 ...
Smith, Peter E. (Monterey, California. Naval Postgraduate School, 1998-03-01);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 ...
Roland, Preston J. (Monterey, California. Naval Postgraduate School, 2006-12);Transport of sediment in coastal regions directly impacts mine countermeasure operations and naval construction efforts. Wave induced shear stress in the surf zone is responsible for entraining sediment particles into ...