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1. (WO2001004825) METHOD AND APPARATUS FOR VERIFYING RFID TAGS

Pub. No.:    WO/2001/004825    International Application No.:    PCT/US2000/018417
Publication Date: Fri Jan 19 00:59:59 CET 2001 International Filing Date: Thu Jul 06 01:59:59 CEST 2000
IPC: G06K 7/00
G06K 19/07
Applicants: INTERMEC IP CORP.
Inventors: EROGLU, Kursat
HELTON, Patrick, L.
WIKLOF, Christopher, A.
Title: METHOD AND APPARATUS FOR VERIFYING RFID TAGS
Abstract:
An RFID tag verifier includes an RF interrogator that transmits a first and second interrogation signal each having a first operational characteristic that differs from the other by a known amount. The RF interrogator receives a first and second return signal corresponding to the respective interrogation signals. A processor determines a response of the RFID tag as defined by a second operational characteristic of the first and second return signals. The verifier can determine the signal strength of the return signal for varying strengths of the interrogation signal. Typically, a flat response is desired. Additionally, or alternatively, the verifier can determine the response in terms of signal strength of the response signals for interrogation signals having different frequencies. In some applications frequency selectivity may be desirable. Additionally, or alternatively, the verifier can determine the response in terms of frequency for interrogation signals having varying strengths. A machine-readable symbol verifier can be coupled to, or formed as part of, the RFID verifier. A printer can be coupled to, or formed as part of, the RFID tag verifier.