Electronic label reading system

Abstract

An electronic label reading system includes an interrogator including a transmitter and a receiver. The system also has a transmitter antenna connected to the transmitter for generating an interrogation electromagnetic field through which objects possessing code responding labels may pass. The code responding labels include label receiving antennas for receiving from the interrogation field a label interrogation signal, and generate label reply signals, and, from the label reply signals, reply electromagnetic fields. The system also has a receiver antenna connected to the receiver for receiving the reply signals from the label reply fields. The interrogation field and label reply fields provide a communication channel from the labels to the interrogator, and the interrogator signals to the labels condition information indicative of the condition of the communication channel.