| 摘要 |
There is disclosed and claimed an electronic identification system including at east one reader and a plurality of transponders to be read by the reader. Each transponder has a normal operational mode 32 wherein it, in response to an interrogation signal from the reader transmits a code 36 to the reader, and a monitor mode 40 wherein it is still sensitive and responsive to signals from the reader, but wherein it does not transmit the code. The reader is adapted to cause a transponder of which the code has been read, to switch from the normal operational mode to the monitor mode, by transmitting a first signal S1 to the transponder. The transponder, while being in the monitor mode, is sensitive to a second signal S2 and responsive upon receipt of the second signal, to reset to the normal operational mode.
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