Error-event detection codes for partial response channels

With an annual increase in density of 100% approaching superparamagnetic limits much stronger error control systems are required in read channels for hard drives. A technique is presented for correcting long errors that are the result of highly colored noise typical for modern magnetic heads and media. We introduce a sofic system-based construction of very high rate codes for correcting errors from a given list, and demonstrate a substantial SNR gain when these codes are used in a scheme that combines the error event detection and the list soft decoding.