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:
Dec. 11, 2012
Filed:
Oct. 04, 2010
James S. Butcher, Desert Hills, AZ (US);
James S. Butcher, Desert Hills, AZ (US);
ADTRAN, Inc., Huntsville, AL (US);
Abstract
A frequency monitoring system comprises a plurality of circuit cards. Each circuit card, such as a primary multiplexer card and a backup or redundant multiplexer card, has an oscillator that provides a reference clock signal. On each circuit card, a respective frequency compare element is configured to receive a clock signal to be measured and to provide a frequency error signal indicating a frequency error of the clock signal relative to an average frequency of a plurality of reference clock signals. Accordingly, the frequency measurements for the circuit cards are based on the same reference frequency (e.g., the average frequency of the reference clock signals from the oscillators).