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. 24, 2002
Filed:
May. 06, 1999
Larry S. Thomson, Grass Valley, CA (US);
Carl H. Alelyunas, Nevada City, CA (US);
3Com Corporation, Santa Clara, CA (US);
Abstract
A method and apparatus for estimating the frequency of a periodic signal and for canceling the interference in a modem signal. Power line noise may interfere with electronic signals. Since power lines may be either 50 Hz or 60 Hz, depending on the country, frequency estimation of the periodic power line noise is necessary. Modem signals are received and autocorrelated in order to identify the periodic characteristics of the signal over time. Once the frequency is identified, the power line noise is modeled based on creating a circular buffer. Initially, the circular buffer is composed of scaled samples of one cycle of the fundamental frequency of the power line noise. Thereafter, samples are received, scaled, and combined with previous buffer values in order to update the buffer. In this manner, the buffer models the power line noise, so that the power line noise may be removed from the system.