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. 20, 2003
Filed:
Dec. 03, 1999
John P. Bradin, Boulder, CO (US);
Hid Corporation, Irvine, CA (US);
Abstract
A reader unit for use in a radio frequency identification (RFID) system delays the initiation of an interrogation operation when potentially interfering radio frequency (RF) energy is detected within an operational frequency range of the system. The reader unit waits a quasi-random period of time after the detection and then senses the spectral environment again to determine whether the energy is still present. If the energy is still present, the reader unit waits another quasi-random period and the process repeats. If there is no energy present or the energy is below a threshold value, the reader unit immediately initiates the interrogation operation. By delaying the initiation of the interrogation operation until the operative frequency range is free of potential interferers, the likelihood of harmful interference effects is significantly reduced.