Variability of target echo and clutter in the 2013 Target and Reverberation Experiment

Abstract

The Target and Reverberation Experiment was conducted in the Gulf of Mexico, off Panama City, Florida. Reverberation, noise, and target echo measurements were carried out for more than a month during April and May 2013, using a fixed source and fixed horizontal array receiver deployed in about 20 m of water. To support modeling efforts, a considerable number of ancillary environmental and transmission loss measurements were made. Various pulses in the 1.8–3.6 kHz frequency band were transmitted day and night, and have produced a rich data set. Initial results by various authors were published in the recent TREX13 Special Issue of the IEEE Journal of Oceanic Engineering. This work extends the analysis, concentrating on the variability of the echoes from various targets: a vertical hose, vertical arrays, a towed echo repeater, the hull of the towing ship, and other persistent bottom scatters, such as shipwrecks. In addition to the ping-to-ping variability of the echoes there are consistent trends, which are not understood, though probably due to oceanographic effects. An attempt will be made to relate the echo variability to measured and modeled reverberation and transmission loss. [Work supported by ONR, Ocean Acoustics, Code 22.]