Electromagnetic identification system for identifying a plurality of coded responders simultaneously present in an interrogation field
First Claim
1. An electromagnetic detection and identification system for detecting and identifying a plurality of responders, each containing a unique code, and simultaneously present in one and the same interrogation field, comprising:
- a transmitter/receiver having;
means for generating an interrogation field;
means for receiving the unique code of each responder sequentially on the same frequency to identify each responder; and
means for adjusting the frequency of the interrogation field to one of a predetermined number of predetermined values; and
a plurality of responders each having;
means to transmit the unique code on the same frequency for all the responders;
means for detecting the instantaneous frequency of the interrogation field;
selection means to repeatedly temporarily deactivate responders from selection until only one single selected responder remains enabled which can transmit an identification code without becoming deactivated until the responder has been identified by the transmitter/receiver said selection means including scrambler means for selecting a random number, a counter which after the detection of a predetermined field frequency begins to count from the random number, and means for generating a starting code, when the responder reaches a predetermined counter position, which results in such a change in frequency of the interrogation field as to temporarily deactivate all responders which have not yet reached said predetermined counter position;
means to block the identified responder by a change in field frequency,means for reactivating the temporarily deactivated responders, andmeans for repeatedly reactivating the selection means until all responders in the interrogation field have been identified and blocked.
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Accused Products
Abstract
An electromagnetic detection and identification system for detecting and identifying a plurality of responders (improved transponders), each containing a unique code, and simultaneously present in one and the same interrogation field generated by a transmitter/receiver. According to the invention, the transmitter/receiver is arranged to adjust the frequency of the interrogation field periodically to one of a predetermined number of predetermined values, and each responder is arranged to detect the instantaneous frequency of the interrogation field, the arrangement being such that, in a number of selection cycles, each time a number of responders temporarily deactivate themselves in dependence upon the instantaneous frequency until one single responder remains which an generate the appurtenant code without becoming deactivated until the responder has been identified by the transmitter/receiver, whereafter the responder concerned is blocked by a change in field frequency, and the temporarily deactivated responders are reactivated, and the selection procedure is repeated until all responders in the interrogation field have been identified and blocked.
163 Citations
12 Claims
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1. An electromagnetic detection and identification system for detecting and identifying a plurality of responders, each containing a unique code, and simultaneously present in one and the same interrogation field, comprising:
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a transmitter/receiver having; means for generating an interrogation field; means for receiving the unique code of each responder sequentially on the same frequency to identify each responder; and means for adjusting the frequency of the interrogation field to one of a predetermined number of predetermined values; and a plurality of responders each having; means to transmit the unique code on the same frequency for all the responders; means for detecting the instantaneous frequency of the interrogation field; selection means to repeatedly temporarily deactivate responders from selection until only one single selected responder remains enabled which can transmit an identification code without becoming deactivated until the responder has been identified by the transmitter/receiver said selection means including scrambler means for selecting a random number, a counter which after the detection of a predetermined field frequency begins to count from the random number, and means for generating a starting code, when the responder reaches a predetermined counter position, which results in such a change in frequency of the interrogation field as to temporarily deactivate all responders which have not yet reached said predetermined counter position; means to block the identified responder by a change in field frequency, means for reactivating the temporarily deactivated responders, and means for repeatedly reactivating the selection means until all responders in the interrogation field have been identified and blocked. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for automatically identifying a plurality of responders of unknown number by transmission of a unique code for each responder sequentially on the same frequency for all responders, comprising:
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selection means for selecting only one of the responders to be identified and for temporarily disabling all the other responders to be identified from transmitting said code at said frequency; identification means for identifying the selected responder by transmission of said code; blocking means for blocking the identified responder from further transmission of said code; reenabling means for reenabling all the temporarily disabled responders to be identified; means for repeatedly activating the selection, identification, blocking and reenabling means until all the responders are identified. - View Dependent Claims (10, 11)
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12. A method for automatically identifying a plurality of responders of unknown by transmission of a unique code for each responder sequentially on the same frequency for all responders, comprising the steps:
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selecting only one of the responders to be identified; temporarily disabling all the other responders to be identified from transmitting said code at said frequency; identifying the selected responder by transmission of said code; blocking the identified responder from further transmission during the identification process; reenabling all the temporarily disabled responders to be identified; and repeating the selecting temporarily disabling, identifying, blocking, and reenabling steps until all the responders are identified.
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Specification