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:
Apr. 20, 2004
Filed:
Apr. 19, 2000
Alan Edward Kaplan, Morris Township, Morris County, NJ (US);
AT&T Corp., New York, NY (US);
Abstract
A method and apparatus for reducing delay distortion of upstream transmissions in a cable television (CATV) distribution plant. Upstream transmission in a CATV distribution plant, i.e., from the customer premises toward the head-end, is made difficult by delay distortion caused by diplexing filters used in bi-directional amplifiers and other components in the CATV distribution plant. A database storing information relating to each cable modem (CM) in the CATV distribution plant is maintained, and the delay distortion for each upstream transmission is calculated using information queried from the database. Delay distortion in the upper portion of the upstream bandwidth in a CATV distribution plant is preferably minimized by assigning CMs having a transmission path that causes relatively minimal delay distortion to the upper portion of the upstream bandwidth. Alternatively, the upper portion of the upstream bandwidth is preferably assigned to the largest number of CMs that have the same number of bi-directional amplifiers in their respective transmission paths. For either frequency assigning technique, a fixed equalizer may be used to further minimize delay distortion. Alternatively, delay distortion for upstream transmissions transmitted on any frequency in the upstream bandwidth may be minimized using a variable equalizer. The delay distortion for an upstream path is calculated using information queried from the database. The tap weights for the variable equalizer are adjusted depending on the calculated distortion for each upstream transmission.