Detection of prescribed error events: application to perpendicular recording

We discuss an error detection technique geared to a prescribed set of error events. The traditional method of error detection and correction attempts to detect/correct as many erroneous bits as possible within a codeword, irrespective of the pattern of the error events. The proposed approach, on the other hand, is less concerned about the total number of erroneous bits it can detect, but focuses on specific error events of known types. We take perpendicular recording systems as an application example. Distance analysis and simulation can easily identify the dominant error events for the given noise environment and operating density. We develop a class of simple error detection parity check codes that can detect these specific error events. The proposed coding method, when used in conjunction with post-Viterbi error correction processing, provides a substantial performance gain compared to the uncoded perpendicular recording system.