Signal processing technique in magnetic recording

Abstract

Magnetic recording systems for hard disk drives (HDDs) have progressed from longitudinal magnetic recording to perpendicular magnetic recording, and now to energy-assisted magnetic recording, to achieve greater capacities and higher areal densities. In this process, signal processing systems have also evolved, from amplitude detection, peak detection, PRML, and iterative decoding, which have contributed to higher densities without compromising the reliability of information while compensating for the characteristics of R/W system. This paper explains the PRML system, which has become the basis for signal processing in magnetic recording and has supported the rapid improvement in areal density of HDDs along with the adoption of MR heads, and the iterative decoding system, which is also used in current HDDs.