The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 2001
Filed:
May. 20, 1999
Stuart Rubin, Philadelphia, PA (US);
Checkpoint Systems, Inc., Thorofare, NJ (US);
Abstract
An apparatus for measuring electrical characteristics of a resonant circuit without physically contacting the resonant circuit. The EAS system includes a numerically controlled oscillator for generating an alternating electric signal, the frequency of the alternating electric signal varying in accordance with a numerical frequency control signal; a transmitting antenna connected to the numerically controlled oscillator for establishing an electromagnetic field within a measurement zone; a receiving antenna for sensing disturbances to the electromagnetic field within the measurement zone; a receiver for receiving signals from the receiving antenna representative of disturbances to the electromagnetic field and for determining the Q and center frequency of the resonant circuit; and a clock having a substantially fixed frequency connected to the numerically controlled oscillator. The frequency of the alternating electric signal is restricted to being an integer multiple of an integer sub-multiple of the clock frequency.