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Author: search.filters.author.Busyatras, WiparatSubject: search.filters.subject.Inter-track interference

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    A simple 2/3 modulation code and bit-flipping technique in bit-patterned media recording systems
    (2018-07-02)
    Busyatras, Wiparat
    ;
    Poompuang, Pitaya
    ;
    Myint, Lin M.M.
    ;
    Warisam, Chanon
    Two-dimensional (2-D) modulation code is considered as one of the key schemes to improve the areal density capability for next generation magnetic recording e.g., bit-patterned media recording (BPMR) technology, due to its advantages such as severe inter-track interference (ITI) suppression and user densities escalation. In this work, a rate-2/3 2-D modulation with a three-reader three-track (3R3T) system is studied where the positions of reader are accordingly optimized with the encoded criteria to obtain the highest bit-error rate (BER) performance. Moreover, we also propose a bit-flipping technique which is one way to extremely improve the overall system performance. Here, the soft-information that are obtained from soft-output Viterbit algorithm (SOVA) detectors will be improved according with the encoded criteria before sending to the proposed decoder. Simulation results demonstrate that significant performance gain can be achieved using these two proposed approaches.
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    Single-track equalization method with TMR correction system based on cross correlation functions for a patterned media recording system
    (2017-01-01)
    Myint, Lin Min Min
    ;
    Warisarn, Chanon
    ;
    Busyatras, Wiparat
    ;
    Kovintavewat, Piya
    Bit-patterned media recording (BPMR) is a promising technology for ultra-high density media, however, there are some challenges that need to be addressed including two-dimensional (2D) interference, and track mis-registration (TMR). The system can experience TMR due to misalignment of the head and the track center. Conventionally, TMR is tackled using a servo system in which the head position offset is estimated by processing the overhead servo sequences before reading the data sequences. However, TMR impairment can also occur when the head is reading data sequences that are beyond the servo mechanism. To address this problem, we proposed TMR detection and correction techniques based on our previous work involving a single-track equalization method for a BPMR system using cross-correlation functions between the single readback signal and each of the training sequences from three adjacent tracks. In this proposed technique, the presence and level of TMR is detected and estimated based on the changes in the value of mean square error (MSE) between the equalized and feedback signals from the detectors after passing through a one-dimensional (1D) target for each sequence. Then, the estimated TMR levels are used in selecting the appropriate equalizer and the generalized partial response (GPR) target pair to tackle the TMR from the readback signal. The simulation results show improvement in the data recovery of a BPMR system using the proposed method when the system is experiencing 2D interference and TMR impairment.