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:
Jul. 16, 1996
Filed:
Nov. 22, 1994
Steven W McLaughlin, Rochester, NJ (US);
Arthur R Calderbank, Princeton, NJ (US);
Rajiv Laroia, Bridgewater, NJ (US);
John M Gerpheide, Silver Spring, MD (US);
Optex Corporation, , DE (US);
AT&T Corp., , NY (US);
Abstract
A system and method for recording multi-level data to a multi-amplitude recording channel encodes binary data to form multi-level data. The multi-level data are recorded to the storage media for later recall. The system utilizes linear, multi-amplitude recording media which allows data to be stored as multi-level data--requiring fewer `bits` to represent the same number of symbols. To obtain greater data density in the storage media, a diffraction limited write laser is utilized, resulting in a smaller write-spot size. Because the read laser is of a longer wavelength, its diffraction limited spot size is larger. As a result, more than one mark is read at a given read time resulting in a inter-symbol interference. Trellis coded modultation techniques are adopted to convert the binary input data into M-ary data having M levels. Further coding is then performed to compensate for the effects of the inter-symbol interference. This is accomplished by precoding the data using a Tomlinson-Harashima precoder. The precoding results in multi-level data (of m levels, where m.ltoreq..infin.).