A study of PRML systems by write and read equalization

A new partial response (PR) channel which contains the write equalizer in addition to conventional PR channel is proposed. Our write equalizer outputs DC-free waveforms of two levels. Our read equalizer can reduce high-frequency noise, and what is more, it has little degradation of eye opening. The PR channels in combination with Viterbi decoder give partial response maximum-likelihood (PRML) systems which exhibit a good performance. The bit error rates for several PRML systems are obtained by computer simulation, where a Lorentzian channel with additive white Gaussian noise is assumed. The results shows that PR(1,1,-1,-1) system has an excellent performance in high density recording for a system in which the small transition spacings required by our write equalization is allowed.<
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