Puttarak, Nattakan
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Puttarak, Nattakan
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Puttarak, N.
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nattakan.pu@kmitl.ac.th
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Item type:Publication, Designed MMSE equalizers for nonlinear magnetic recording channels(2014-01-01); Writing process in hard disk drives (HDD) is affected from nonlinearity. Normally, nonlinearity is not easy to be avoided or removed since it is unexpected and caused by various sources. In this paper, we review a description of a nonlinearity behavior by using a Volterra model, and using a random binary number to generate an input data. The Volterra model can describe both linear and nonlinear parts of the read-back signals in terms of the volterra equations. In addition, we propose to use an MMSE method to equalize the read-back signals with nonlinearity using various constraints before applying the Viterbi detector. For a 2nd-order Volterra model, the results show that the equalizer with g<inf>1</inf> =1 constraint gives the lowest MMSE values. Furthermore, as the nonlinearity level increases, the bit error rate (BER) performance degrades. © 2014 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Reduced-nonlinear effect on magnetic recording channels using MMSE equalizer(2015-01-01); This paper considers the nonlinear effect on magnetic recording channels in order to reduce the system distortion. We propose the designed minimum-mean square error (MMSE) equalizer and targets for a high density perpendicular magnetic recording to combat the nonlinear transition shift (NLTS) in a channel characterized by jitter noise and additive white Gaussian noise (AWGN). Due to the complex nature of nonlinear effects, the nonlinearity of a read-back signal is modeled by the second order Volterra model consisting of linear and nonlinear parts. The bit-error rate (BER) of the nonlinear-affected system using the designed MMSE equalizer is significantly decreased. The results show that the proposed MMSE equalizer with g<inf>t</inf>=1 constraint can decrease the inter-symbol interference (ISI) that causes nonlinearity and also improves a system performance.