Acoustic Transmission Loss and Pulse Time-Spread Measured Off the South Carolina Coast During the 1997 Littoral Warfare Advanced Development System Concept Validation Experiment

Abstract

Abstract : Acoustic transmission loss and pulse time-spread measurements were performed off the South Carolina coast as part of the Littoral Warfare Advanced Development (LWAD) environmental measurement support provided for the 1997 System Concept Validation (SCV 97) experiment. Although the extensive acoustic propagation survey originally planned for this experiment was canceled due to hardware failure, high-quality acoustic transmission loss data at three ranges (2, 3, and 4 run) were collected aboard the R/V Gosport at two sites using the LWAD echo repeater F-56 acoustic projector and drifting AN/SSQ-57A sonobuoys. High-quality transmission loss and time-spread data were also provided by the SQW-53C LFM signal (300 ms duration, 200 Hz bandwidth) generated by U.S.S. Nicholson as it made a straight-line run to acoustic receivers deployed from the R/V Gosport. These data produce transmission loss values of 80 to 90 dB at a 4 nm range, which agree well with measurements made near this general site in LWAD FTE 96-2, but are 10 dB greater than predicted by several modeling efforts before the LWAD FTE 96-2 and SCV 97 experiments. Analysis of the SQS-53C data shows significant time-spread and a strong multipath acoustic propagation environment.