Detection of a resonant target in shallow water using iterative, single‐channel time reversal at low frequencies (2–23 kHz).

Abstract

Iterative time reversal with a single‐channel transducer has been shown to enhance echoes from resonant targets both in scaled high‐frequency (0.5–2‐MHz) laboratory experiments [Waters et al., IEEE UFFC 56, 1429 (2009)] and in mid‐frequency (20–200‐kHz) pond experiments [Dzikowicz et al., J. Acoust. Soc. Am. 123, 3755 (2008)]. These techniques are applied to study scattered returns from a proud, spherical target at low frequencies, 2–23 kHz, in a littoral environment. Monostatic scattering experiments are conducted in the Gulf of Mexico near Panama City, FL in 14‐m‐deep water. The target, a 60‐cm‐diameter stainless steel spherical shell (1.5 cm thick), rests on a sandy bottom at a range of 35 m from a rail‐mounted source‐receiver pair positioned at a height of 2.3 m from the bottom. Through iterative retransmission of windowed and time reversed scattering returns, enhancement of target echoes with respect to background noise and reverberation is explored. Frequencies to which the time reversal process con...