Reducing the Complexity of the Skew Angle Detector and Corrector for Bit-Patterned Magnetic Recording

DOI: 10.14416/


  • Santi Koonkarnkhai Advanced Signal Processing for Disruptive Innovation Research Center, Nakhon Pathom Rajabhat University
  • Piya Kovintavewat Advanced Signal Processing for Disruptive Innovation Research Center, Nakhon Pathom Rajabhat University


Magnetic recording, Bit-patterned media, Skew angle, Viterbi detector


A current magnetic recording technology is approaching the superparamagnetic limitation, which makes it impossible to increase an areal density (AD) beyond 1 tera-bit per square inch (Tb/in2). A bit-patterned magnetic recording (BPMR) technology is an alternative solution to replace the current technology, which can achieve AD ​​up to 4 Tb/in2. Practically, a skew angle (SA) is one of the major problems that cause faults in the detector.  Without SA detection and correction, the overall BPMR system has greatly deteriorated.  This paper presents a method to reduce the complexity of the SA detector and corrector, which can be achieved by comparing the target coefficients and the BPMR channel impulse response using a SA profile.  When the SA is detected, a suitable pair of targets and equalizer for the detected SA will be employed in the data detection process. In addition, the complexity reduction makes the trellis diagram used in the Viterbi detector have a fewer number of states and branches, specifically from 36 states with 6 outgoing branches to 32 states with 4 outgoing branches. Simulation results show that the proposed system can provide similar performance to the conventional system at the AD of less than 2.5 Tb/in2.


Download data is not yet available.


A. Ali, J. Qadir, R. Rasool, A. Sathiaseelan, A. Zwitter, and J. Crowcroft, Big data for development: Applications and techniques, Big Data Analytic, 2016, (1), 2.

J. Lin, R. Luley, and K. Xiong, Active learning under malicious mislabeling and poisoning attacks, 2021 IEEE Global Communications Conference (GLOBECOM), Proceeding, 2021, 1-6.

D.S. Kuo, K.Y. Lee, X.M. Yang, S. Xiao, Y. Hsu, Z. Yu, M. Feldbaum, T. Klemmer, Y. Kubota, J.-U. Thiele, P. Steiner, K. Wago, S. Dallorto and D. Olynick Heated dot magnetic recording media - Path to 10 TDOTS/in2, 2016 International Conference of Asian Union of Magnetics Societies (ICAUMS), Proceeding, 2016, 1.

S. Koonkarnkhai, P. Keeratiwintakorn, and P. Kovintavewat, Target and equalizer design for high-density bit-patterned media recording, ECTI-CIT Transactions, 2012, 6(2), 128-135.

Y. Wang and B.V.K.V. Kumar, Improved multitrack detection with hybrid 2-d equalizer and modified Viterbi detector, IEEE Transactions on Magnetics, 2017, 53(10), 1- 10.

S. Koonkarnkhai, C. Warisarn and P. Kovintavewat, An iterative two-head two-track detection method for staggered bit-patterned magnetic recording systems, IEEE Transactions on Magnetics, 2019, 55(7), 1-7.

T. Wu, M.A. Armand and J. R. Cruz, Detection-decoding on BPMR channels with written-in error correction and ITI mitigation, IEEE Transactions on Magnetics, 2014, 50(1), 1-11.

L.M.M. Myint, P. Supnithi, and P. Tantaswadi, An inter-track interference mitigation technique using partial ITI estimation in patterned media storage, IEEE Transactions on Magnetics, 2009, 45(10), 3691-3694.

S. Nabavi, B.V.K.V. Kumar, and J.G. Zhu, Modifying Viterbi algorithm to mitigate intertrack interference in bit-patterned media, IEEE Transactions on Magnetics, 2007, 43(6), 2274-2276.

S. Nabavi, B.V.K.V. Kumar and J.A. Bain, Mitigating the effects of track mis-registration in bit-patterned media, 2008 IEEE International Conference on Communications, Proceeding, 2008, 2061-2065.

L. Alink, J.P.J. Groenland, J. de Vries and L. Abelmann, Determination of bit patterned media noise based on island perimeter fluctuations, IEEE Transactions on Magnetics, 2012, 48(11), 4574-4577.

Y. Ng, B.V.K.V. Kumar, K. Cai, S. Nabavi, and T.C. Chong, Picket-shift codes for bit-patterned media recording with insertion/ deletion errors, IEEE Transactions on Magnetics, 2010, 46(6), 2268-2271.

A.R. Iyengar, P.H. Siegel and J.K. Wolf, Write channel model for bit-patterned media recording, IEEE Transactions on Magnetics, 2011, 47(1), 35 -45.

Z. He, J. Mou, K.S. Chan, S.H. Lam and W. Lin, A near zero skew actuation mechanism for hard disk drives, Microsystem Technologies, 2015, 21(1), 131-137.

Z. He, J. Mou and K.S. Chan, Mechanisms of minimum skew angle actuation for hard disk drives, The 3rd International Conference on Control, Mechatronics and Automation (ICCMA 2015), Proceeding, 2016, 02002.

K. Kankhunthod, C. Warisarn, S. Koonkarnkhai, and P. Kovintavewat, Multilayer perceptron-based skew-angle estimation for bit-patterned magnetic recording, The 36th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2021), Proceeding, 2021, 1-3.

S. Koonkarnkhai, C. Warisarn and P. Kovintavewat, A simple skew angle detection and suppression method for bit-patterned magnetic recording, AIP Advances, 2021, 11(1), 015229.

S. Nabavi and B.V.K.V. Kumar, Two-dimensional generalized partial response equalizer for bit-patterned media, IEEE International Conference on Communications, Proceeding, 2007, 6249-6254.

J. Moon and W. Zeng, Equalization for maximum likelihood detector, IEEE Transactions on Magnetics, 1995, 31(2), 1083-1088.






บทความวิจัย (Research article)