Spatial diversity in application of the decomposition of the time reversal operator (DORT) method to imaging of an extended target

Taking advantage of the multipath propagation in shallow water waveguide, high resolution can be achieved with the decomposition of the time reversal operator method. In this paper, we investigate how to use the spatial diversity for imaging of an extended target. It is assumed that the target is composed of an infinite number of random, isotropic, and independent scatterers, uniformly distributed over an unknown region. The eigenvalues and eigenvectors associated with the target are first determined. We then employ the frequency characterizations of scatterers from a singular value decomposition of the time reversal operator to localize and image the target. Tank experiments are carried out for a steel cylinder in two kinds of random media: a shallow water waveguide with multiple scatterers and without scatterers. The effects of the random media on the choice of the parameters of the signal processing are also studied.