Enhanced identification system

A method of identifying a plurality of transponders comprising:

• transmitting a reader signal from a reader;
• receiving the reader signal in each transponder;
• recognising in the reader a transponder signal transmitted from a transponder and immediately issuing a mute instruction from the reader, muting all other active transponders and passing control to the said transponder, without the need for a specifically timed acknowledgement to the said controlling transponder;
• and
• issuing an acceptance instruction from the reader after the controlling transponder signal has been successfully received by the reader, the acceptance instruction being a modification of the reader signal, wherein the modification of the reader signal occurs immediately after successful identification of the controlling transponder signal, the modification of the reader signal always occurring for a period shorter than the length of the controlling transponder signal.

A transponder comprising:

• receiver means for receiving a reader signal;
• transmission means for transmitting a transponder signal containing data which identifies the transponder, whereby in a set of transponders, two or more transponders may transmit their transponder response signals in response to receiving the reader signal;
• and
• control means whereby on recognising a mute instruction in the reader signal all other active transponders in the set but one are muted and control is passed to said one transponder, without the need for a specifically timed acknowledgement to the said controlling transponder, the control means recognising an acceptance instruction from the reader after the controlling transponder signal has been successfully received by the reader, the acceptance instruction being a modification of the reader signal, wherein the modification of the reader signal occurs immediately after successful identification of the controlling transponder signal, the modification of the reader signal always occurring for a period shorter than the length of the controlling transponder signal.

An integrated circuit for use in a transponder, comprising:

• receiver means for receiving a reader signal;
• transmission means for transmitting a transponder signal containing data which identifies the transponder, whereby in a set of transponders, two or more transponders may transmit their transponder response signals in response to receiving the reader signal;
• and
• control means whereby on recognising a mute instruction in the reader signal all other active transponders in the set but one are muted and control is passed to said one transponder;
• without the need for a specifically timed acknowledgement to the said controlling transponder, the control means recognising an acceptance instruction from the reader after the controlling transponder signal has been successfully received by the reader, the acceptance instruction being a modification of the reader signal, wherein the modification of the reader signal occurs immediately after successful identification of the controlling transponder signal, the modification of the reader signal always occurring for a period shorter than the length of the controlling transponder signal.