An experimental study of drive-by single channel time reversal using scaled targets and clutter

Abstract

Previous results suggest that iterative single channel time reversal (TR) is a promising, simple and inexpensive technique to enhance the backscatter signature of elastic objects and to simultaneously focus on its dominant resonance frequency in the presence of noise and clutter (Pautet et al. 2005), (Waters et al. 2009). However, to the best of our knowledge, these and other studies have only considered the case when the sonar system, target, and clutter are fixed or stationary, i.e., not moving. This is an unrealistic assumption since the sonar platform is typically moving. In fact, motion and environmentally-induced clutter scintillations may actually be beneficial for TR when the dominant target resonance varies slowly with aspect in clutter-limited noise environments. Theoretical arguments in (Kirsteins et al. 2009) suggest TR provides additional signal-to-noise ratio (SNR) enhancements against clutter under these circumstances. To confirm this hypothesis, a drive-by TR experiment was conducted in a tank using scaled elastic targets/clutter sources with the platform motion simulated by rotating the target/clutter during each TR iteration. Quantitative analysis in regards to detecting the dominant resonance clearly shows that TR in drive-by mode provides SNR enhancements against clutter.