Browse Prior Art Database

Write Pre-Compensation Algorithm for High Linear Density Magnetic Recording

IP.com Disclosure Number: IPCOM000036957D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+3]

Abstract

Disclosed is an algorithm for the compensation of a bit-shift in a magnetic recording process. The purpose of a conventional pre-compensation algorithm is only to cancel the bit shift due to inter- symbol interference in a read process. However, the new algorithm disclosed herein can compensate the bit shift not only in the read process but also in the write process. The bit shift in the write process is a position shift of a magnetic transition written on a disk. This is caused by an interaction between a head field and a transition field.

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Write Pre-Compensation Algorithm for High Linear Density Magnetic Recording

Disclosed is an algorithm for the compensation of a bit-shift in a magnetic recording process. The purpose of a conventional pre-compensation algorithm is only to cancel the bit shift due to inter- symbol interference in a read process. However, the new algorithm disclosed herein can compensate the bit shift not only in the read process but also in the write process. The bit shift in the write process is a position shift of a magnetic transition written on a disk. This is caused by an interaction between a head field and a transition field.

Fig. 1 shows a write data bit-stream to be pre-compensated. The central "1" bit is attended whether it should be compensated or not. The pre-compensation time and its direction (early or late) depend on the bit values of both A and B in the simplest case. Tables 1 and 2 show the conventional algorithm and the new one, respectively. In the new algorithm, "DO" is newly introduced to cancel and the bit shift in the write process. The DO-shift occurs only when an early bit "A" is "1" and is always directed too late (i.e., delay), because the nearest two transitions are not near to each other in an uncompensated write process.

A small bit shift remarkably affects the read performance of a magnetic recording system. The bit shift in the write process is not negligible at a high linear density. Thus, this algorithm can improve

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the performance...