Identification system

摘要

A system and method for communicating between an identification reader 12 and a transponder unit 10 is disclosed herein. A first interrogation signal is transmitted from the reader 12. This first interrogation signal having a first read range. A first response signal is then received at the reader 12 after which a second interrogation signal is transmitted from the reader 12. The second interrogation signal has a second read range which is different than said first read range. The read range can be varied by varying either the amplitude or duration of the power level of the interrogation signal. A second response signal is then received at the reader 12. These consecutive responses are then compared determine a correct response signal which can be displayed. <IMAGE>