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:
Nov. 28, 2000
Filed:
Jun. 04, 1998
Lisa Fredrickson, Ojai, CA (US);
Reza M Dehmohseni, Winnetka, CA (US);
Seagate Technology LLC, Scotts Valley, CA (US);
Abstract
A Viterbi PRML system and method providing a new code with distance properties such that some tribits are allowed but no longer sequences are allowed. A code rate 8/ 9 is constructed for EPR4 and E.sup.2 PR4 channels and the system independently maps 8-bit blocks of user data to 9-bit channel sequences. The precoder has transfer function, f(D)=1/(1.sym.D), and produces a binary channel input x(D), which is fed to a coder, to provide an output signal y(D), which is transmitted and corrupted by noise. The corrupted signal is received and fed to a Viterbi detector. The signal is decoded to produce an estimate of the 8-bit data bytes, as reconstructed to be freed from noise corruption. The encoding protocol of the invention is implemented in the encoder. The protocol is: no sequence of 4 consecutive transitions occurs in any 9-bit codeword; no 9-bit codeword ends with a sequence of 2 or more consecutive transitions; no 9-bit codeword begins with more than 2 consecutive transitions; and sequences of 3 consecutive transitions, if any, begin only on a 2nd, 4th, 6th, or 9th bit of said 9-bit codeword. The protocol is preferably augmented by an additional constraint: no 9-bit codeword has the same 1st, 3rd, 5th, 7th, and 9th bit. Other limitations on coding are described to enhance the performance of the system.