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Resonant circuit detection measurement and deactivation system employing a numerically controlled oscillator

  • US 6,359,562 B2
  • Filed: 03/16/2001
  • Issued: 03/19/2002
  • Est. Priority Date: 05/20/1999
  • Status: Expired due to Fees
First Claim
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1. An apparatus for deactivating a security tag in a deactivation zone comprising:

  • a numerically controlled oscillator for generating a first alternating electric signal, the frequency of the first alternating electric signal varying in accordance with a numerical frequency control signal;

    a clock having a substantially fixed frequency connected to the numerically controlled oscillator for providing a frequency reference to the numerically controlled oscillator, the frequency of the first alternating electric signal being restricted to an integer multiple of an integer sub-multiple of the frequency of the clock; and

    a transmitting antenna connected to the numerically controlled oscillator for receiving the first alternating electric signal and establishing a first electromagnetic field within the deactivation zone wherein the first electromagnetic field interacts with the security tag to deactivate the security tag.

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