R&D: Study of 3D Equalization for Reproducing Double-Layer Magnetic Recording Medium

IEEE Transactions on Magnetics has published an article written by Yasuaki Nakamura, Madoka Nishikawa, Graduate School of Science and Engineering, Ehime University, Matsuyama, 790-8577, Japan. Yasushi Kanai, Department of Information and Electronics Engineering, Niigata Institute of Technology, Kashiwazaki, 945-1195, Japan, and Yoshihiro Okamoto, Graduate School of Science and Engineering, Ehime University, Matsuyama, 790-8577, Japan.

Abstract: “To increase the recording density of hard disk drives (HDD), three-dimensional (3D) magnetic recording with multiple recording layers is attracting much attention as a next-generation recording method. We have reported that two-dimensional (2D) partial response maximum likelihood (PRML) can achieve good BER performance using the PR channel obtained from the differential-phase bit response in the 3D magnetic recording system with a double recording layer. In this study, we realize the 3D equalization by the 2D finite impulse response (FIR) (2D-FIR) filter and 2D-PRML system over two layers and evaluate the 3D equalization to further increase the recording density. The transfer function of the 2D-PR channels are determined by the response for the in-phase or differential-phase bits in a double-layer magnetic recording medium. The results show that the 2D-PRML channels with 3D equalization based on the differential-phase transfer function achieve a good bit error rate performance for system noise.“