Identification system
DCFirst Claim
1. A method of identifying a plurality of transponders in an interrogation comprising transmitting an interrogation signal to the transponders and receiving response signals from the transponders, each transponder being capable of transmitting the response signal at any time during a waiting period, wherein each transponder alters the maximum length of the waiting period during the interrogation process for retransmitting the response signal at a random time during that altered waiting period.
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Abstract
A method and system for identifying a plurality of transponders in an interrogation involves transmitting an interrogation signal to the transponders and receiving, at a reader, response signals from the transponders. Each transponder period, and alters the maximum length of the waiting period during the interrogation process.
87 Citations
33 Claims
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1. A method of identifying a plurality of transponders in an interrogation comprising transmitting an interrogation signal to the transponders and receiving response signals from the transponders, each transponder being capable of transmitting the response signal at any time during a waiting period, wherein each transponder alters the maximum length of the waiting period during the interrogation process for retransmitting the response signal at a random time during that altered waiting period.
- 2. An identification system comprising an interrogator and a plurality of transponders, the interrogator including a transmitter for transmitting an interrogation signal to the transponders, each transponder including a receiver for receiving the interrogation signal, a transmitter for transmitting a response signal after receipt of the interrogation signal and means for generating the response signal at any time during a waiting period, wherein each transponder has means for altering the maximum length of the waiting period during interrogation of the transponders by the interrogator for retransmitting the response signal at a random time during that altered waiting period.
- 14. A transponder including a receiver for receiving an interrogation signal from an interrogator, a transmitter for transmitting a response signal after receipt of the interrogation signal and means for generating the response signal at any time during a waiting period, wherein the transponder has means for altering the maximum length of the waiting period during interrogation by the interrogator for retransmitting the response signal at a random time during that altered waiting period.
- 24. An integrated circuit for use in a transponder including a receiver for receiving an interrogation signal, a transmitter for transmitting a response signal after receipt of the interrogation signal and means for generating the response signal at anytime during a waiting period, characterised in that there is provided control means for altering the maximum length of the waiting period during interrogation of the transponder by the interrogator for retransmitting the response signal at a random time during that altered waiting period.
Specification