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:
Sep. 28, 1999
Filed:
Sep. 21, 1995
Arthur Robert Calderbank, Princeton, NJ (US);
Ehud Alexander Gelblum, New York, NY (US);
Lucent Technologies Inc., Murray Hill, NJ (US);
Abstract
Method and apparatus for encoding digital information to be recorded on a magnetic medium is disclosed. The invention provides for receiving a sequence of (2.sup.m n+d) user bits, mapping the sequence of user bits to 2.sup.m dc-free codewords, and recording the 2.sup.m dc-free codewords on a magnetic medium. A modulation coder, which includes a memory containing multiple non-intersecting subconstellations of dc-free codewords, performs the mapping in a non-equiprobable manner such that a particular codeword from a larger subconstellation is more likely to be used than a particular codeword from a smaller constellation. Less desirable codewords, such as those containing relatively long strings of bits having the same value, are assigned to the smaller subconstellations, thereby lessening the likelihood of loss of timing and gain parameters in the system, as well as maximizing the transmission rate and efficient use of the set of possible dc-free sequences of a given length.