First tests of the DORT method at 12 kHz in a shallow water waveguide

The Decomposition of the Time Reversal Operator (DORT method) has been introduced by Prada et al. (1996) as a generalization of the iterative time-reversal process. The effectiveness of this method for ultrasonic detection and selective focusing on different scatterers in an inhomogeneous media has been shown. The robustness of the method in an ultrasonic wave guide has been demonstrated by Mordant et al. (1999). Whereas the performance of classical detection methods usually decreases due to multiple reflections at the waveguide interfaces, the DORT method takes advantage of the wave guide boundaries and multi-path propagation in order to improve spatial resolution. In this work, we present the first experiment in a realistic shallow water waveguide with a 24 elements source receiver array at 12 kHz central frequency. The DORT method is applied in order to detect two targets at 27 m distance. Numerical and experimental backpropagation of the dominant singular vectors of the array response matrix enable the localization of the individual targets.