Patent ID: 6538564
Filing Date: 2003-03-25
Classification: G01V,G06K

Abstract:
A label reading system including:an interrogator including a transmitter for generating an interrogation signal and a receiver for detecting and decoding a reply signal; an interrogation field creation means including a transmitter antenna connected to said transmitter for generating from said interrogation signal an electromagnetic interrogation field through which an object possessing a code responding label may pass; said code responding label including a label receiving antenna for receiving from said interrogation field a label interrogation signal, means for generating label reply signals and means for generating from said label reply signals an electromagnetic reply field; said label reply signals being generated intermittently by the label at intervals which are timed within the label; said code responding label further including means for detecting a label excitation level provided by said interrogation field at said label, and means for providing an encoded indication of said label excitation level in said label reply signals; a receiver antenna connected to said receiver for receiving said reply signals from said reply field; said receiver including means for detecting starting and stopping times of said reply signals; and said interrogator providing a timing signal to the labels upon detecting that a reply signal or an overlapping series of reply signals has just ceased.