EAS system with requency hopping
October 13, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3868669 Article surveillance Surveillance method and system with electromagnetic carrier and plural range limiting signals Method and apparatus for selective electronic surveillance Surveillance systems FM/AM Electronic security system Electronic security system with noise rejection Signal receptor-reradiator and surveillance tag using the same Tag device and method for electronic article surveillance Method and apparatus for enhancing detection of electronic article surveillance tags in close proximity to electrically conductive objects Patent #: 5109217 InventorsAssigneeApplicationNo. 959685 filed on 10/13/1992US Classes:340/572.2, Specified relationship between field and detection frequencies (e.g., nth order harmonics)340/551, Disturbance of magnetic field340/572.4Specified processing arrangement for detected signalExaminersPrimary: Swann, GlenAttorney, Agent or FirmInternational ClassG08B 013/187AbstractAn EAS system in which a transmitter transmits an RF transmitter signal into an interrogation zone and a receiver receives RF signals from the interrogation zone. The received RF signals include any RF tag signals generated by tags situated in the zone and adapted to respond to the RF transmitter signal. In order to reduce interference effects, the RF carrier frequency of the transmitter signal is adapted to take on a plurality of different frequency values during different ones of a plurality of finite dwell time periods of the RF transmitter signal.Other References
Field of SearchDisturbance of magnetic field | |
