Patent ID: 6247159
Filing Date: 2001-06-12
Classification: G11B,H03M

Abstract:
An EPRML data storage system for storing data on a storage medium in a manner that avoids catastrophic error sequences in a media code sequence of symbols, comprising:a modulation encoder configured to encode user data that is to be stored on the storage medium, 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; anda precoder configured to precode the channel code modulation output symbol sequence according to a precoding transfer function, wherein the precoding 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 preceding prevents the media code sequence of symbols from including EPRML catastrophic error sequences greater than the determined length.