Patent ID: 6035435
Filing Date: 2000-03-07
Classification: G11B,H03M

Abstract:
A method of avoiding catastrophic error sequences in a media code sequence of symbols for data storage on a storage medium according to EPRML, comprising:modulation encoding user data which is to be stored on the storage medium using a modulation encoder, wherein the modulation encoder outputs a channel code modulation output symbol sequence, and the modulation encoder uses a modulation code that is defined according to a modulation criteria wherein the set of all possible modulation output symbol sequences is constrained in a manner which excludes certain excluded modulation output symbol sequences; andprecoding the channel code modulation output symbol sequence according to a precoding transfer function, wherein the preceding transfer function transforms the channel code modulation output symbol sequence into a media code sequence of symbols and the precoding transfer function is defined so that when modulation encoding is performed according to the modulation criteria, the media code sequence of symbols is constrained to exclude EPRML catastrophic error sequences of greater than a determined length;whereby the combination of the modulation encoding and the precoding prevents the media code sequence of symbols from including EPRML catastrophic error sequences greater than the determined length.