Target location based on time focusing of time-reveral retransmitting signals

A new time-reversal imaging method based on the time focusing is presented. The time focusing behavior of the retransmitted time-reversal back-propagating waves from the time-reversal mirror (TRM) at a single target position is extended to multi target positions by using a grouping technique that divides the receiving array as a group of sub-arrays. The number of targets can exceed that of either the transmitters or the receivers. Locally normalized schemes can be employed to favor farer or weaker targets that may be swamped by nearer or stronger targets.