초록 ▼

An electronic article surveillance (EAS) system, comprising: an antenna for capturing signals generated in an interrogation zone, the captured signals including noise and, when at least one marker is present in the interrogation zone, a ring down signal with a characteristic frequency generated resp

An electronic article surveillance (EAS) system, comprising: an antenna for capturing signals generated in an interrogation zone, the captured signals including noise and, when at least one marker is present in the interrogation zone, a ring down signal with a characteristic frequency generated responsive to a magnetic field transmitted into the interrogation zone; a receiver having a signal processor for extracting amplitude and frequency information from the captured signals; and, a detector responsive to both the amplitude and frequency information for validating when the at least one marker is in the interrogation zone. The signal processor determines an average frequency of all markers in the interrogation zone, the detector being responsive to the average frequency. The signal processor can further determine successive frequency deviations of sequential frequency measurements and magnitudes of the deviations, the detector being responsive to the magnitudes of the deviations.

대표청구항 ▼

[ What is claimed is:] [1.] An electronic article surveillance (EAS) system, comprising:an antenna for capturing signals generated in an interrogation zone of said EAS system during successive receive windows of a transmit and receive sequence, said captured signals from said interrogation zone incl

[ What is claimed is:] [1.] An electronic article surveillance (EAS) system, comprising:an antenna for capturing signals generated in an interrogation zone of said EAS system during successive receive windows of a transmit and receive sequence, said captured signals from said interrogation zone including noise and, when at least one of a plurality of markers is present in said interrogation zone, a ring down signal with a characteristic frequency generated by said at least one marker responsive to a magnetic field transmitted into said interrogation zone;a receiver coupled to said antenna having a first signal processor for extracting amplitude information and frequency information from said captured signals, said frequency information including a measured time duration of a portion of an IF waveform signal produced as a result of said ring down signal, said measured time duration proportional to said characteristic frequency; and,a detector responsive to both said amplitude information and said frequency information for validating when said at least one marker is in said interrogation zone.