Time Reversal Imaging Based on Synchronism

Abstract

A new time-reversal (TR) imaging procedure is proposed in this letter. The traditional TR imaging method shows a snapshot of the amplitude values of the time-reversed retransmitted signals from the TR mirror (TRM) at a specified instant. The present approach gives the image based on the fact that the retransmitted signals from individual elements of the TRM achieve their maximum values synchronously at target positions but nonsynchronously at nontarget positions. That is, a target is located based on whether the retransmitted signals achieve their maximum values at the same instant at the point. A grouping technique that divides the TRM into many sub-TRMs is devised to discriminate multitargets by further enhancing the synchronism at target positions. A normalization scheme is introduced to permit all targets to be displayed at the same visibility to avoid swamping of farther or weaker targets by nearer or stronger ones. Several examples are provided to validate the proposed method and its merits.