PRML Systems for Perpendicular Magnetic Recording

Abstract

A bstract-Partial response maximum-likelihood(PRML) systems using an MR head and a double layer perpendicular medium are studied. The bit-error rate performance of PRML systems characterized by the polynomials with the positive coefficients for the (1,7) code and the negative coefficients for the 8/9 code is evaluated. The PRML system for the (1,7) code has a large minimum Euclidean distance and a small noise spectrum compared with those for the 8/9 code. This results in a significant performance improvement. Among PRML systems discussed in this study, PR(l, 2, 3, 2, l)ML exhibits the best performance and improves the SNR by about 13.8 dB over that of PR4ML for the 8/9 code at a bit-error rate of 10-4 and a normalized linear density of 2.5.

Performance comparison of (1,7) RLL coded PRML systems and 16/17 (0,6/6) coded PRML systems in perpendicular magnetic recording using double‐layered media

“…5. From the figure it is clear that for K p = 2.5, the (1,7) RLL coded PR (1,3,4,4,3,1)ML system shows better error rate performance (although very small) than the previously proposed PR (1,2,3,2,1)ML system [10]. Here an SNR improvement of about 0.4 dB is obtained with a bit error rate of 10 4 .…”

“…The authors have already proposed an efficient PRML system that realizes high-density recording by combining the MR head with perpendicular double-layered media [10,11].…”

Simplification of neural network equalizer for perpendicular magnetic recording

“…In current hard disk drives using longitudinal recording, the partial response maximum likelihood (PRML) method [2] is an indispensable signal processing method and is considered to be an important signal processing method even in perpendicular magnetic recording. Various versions of the positive coefficient PRML method have been proposed as the PRML method for perpendicular magnetic recording on a two-layer medium [3][4][5][6]. When a GMR head having a high playback sensitivity is used in perpendicular magnetic recording, the jitter medium noise produced by fluctuations in the magnetic transition point becomes dominant [7].…”