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Title: System and method for simultaneously collecting serial number information from numerous identity tags

A system and method for simultaneously collecting serial number information reports from numerous colliding coded-radio-frequency identity tags. Each tag has a unique multi-digit serial number that is stored in non-volatile RAM. A reader transmits an ASCII coded "D" character on a carrier of about 900 MHz and a power illumination field having a frequency of about 1.6 Ghz. A one MHz tone is modulated on the 1.6 Ghz carrier as a timing clock for a microprocessor in each of the identity tags. Over a thousand such tags may be in the vicinity and each is powered-up and clocked by the 1.6 Ghz power illumination field. Each identity tag looks for the "D" interrogator modulated on the 900 MHz carrier, and each uses a digit of its serial number to time a response. Clear responses received by the reader are repeated for verification. If no verification or a wrong number is received by any identity tag, it uses a second digital together with the first to time out a more extended period for response. Ultimately, the entire serial number will be used in the worst case collision environments; and since the serial numbers are defined as being unique, the final possibilitymore » will be successful because a clear time-slot channel will be available.« less
  1. (Manteca, CA)
Issue Date:
OSTI Identifier:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5591951
Contract Number:
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Country of Publication:
United States
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