Field generation and reception system for electronic article surveillance
First Claim
1. In a system for detecting the presence of a ferromagnetic marker in an interrogation zone, including first and second generating means for generating first and second magnetic fields, respectively, at first and second frequencies, respectively, and wherein said second frequency is substantially lower than said first frequency, the improvement wherein said first generating means comprises means for generating an alternating field at said first frequency and said second generating means comprises means for generating a rotating field at said second frequency.
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Accused Products
Abstract
An electronic surveillance system includes a signal generator for generating a magnetic field, a signal receiver within the influence of the magnetic field, and a ferromagnetic marker adapted to pass in the field for detection. The signal received includes an arrangement for generating a non-rotating field at a first frequency, and a rotating field at a second frequency that is lower than the first frequency.
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Citations
4 Claims
- 1. In a system for detecting the presence of a ferromagnetic marker in an interrogation zone, including first and second generating means for generating first and second magnetic fields, respectively, at first and second frequencies, respectively, and wherein said second frequency is substantially lower than said first frequency, the improvement wherein said first generating means comprises means for generating an alternating field at said first frequency and said second generating means comprises means for generating a rotating field at said second frequency.
Specification