Electronic article surveillance system utilizing synchronous integration

Abstract From the Canadian patent

Abstract of the Disclosure An electronic article surveillance system employs a resonant tag attached to an article being protected. An interrogation transmitter whose transmission frequency is periodically swept through the resonant frequency of the tag is positioned near an exit of the protected area. The resonant tag is periodically energized by the transmitter as the transmitter frequency passes through the resonant frequency of the tag to cause the tag to emit a periodic tag signal at the sweep rate of the transmitter. The tag signal is received by a receiver that generates an alarm upon the detection of a tag signal. The receiver employs synchronous integration in the form of a dual …