• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.39-42
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• 2002

A new adaptive PRML architecture, considered not only DVD-ROM but also DVD-Multi including DVD-RAM as well, is presented to demonstrate its superiority over the conventional analog channel in a DVD system. For this new architecture, channel adaptation algorithm using gain controlled type of FIR filter, and asymmetry compensation algorithm using expected level adaptation of viterbi decoder are presented. In addition, a method of modelling the disk tilt and asymmetrical read-back signal are discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.17-26
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• 2006

The analog Viterbi decoder for the PR (1 2 2 1) which is used for BVD read channel is designed with circular analog parallel circuits. Since the inter symbol interference is serious problem in the high density magnetic storage device or DVD, the PRML technology is normally employed for the purpose of minimizing the decoding error. The feature of the PRML technology is with the multi-level coding according to the predetermined combining rule among the neighboring symbols and with the decoding according to the known combining rule. Though the conventional PRML technology is implemented with the digital circuits, the recent trend towards this end is with the utilization of the analog circuits due to the requirements of higher speed and lower power in the DVD read channel. In this study, the Viterbi decoder which is the bottleneck of the PRML implementation is designed with the analog parallel circuit structure. The designed Viterbi decoder for the PR (1 2 2 1) signal shows 3 times faster in the speed and 1/3 times less in the power consumption than thoseoftheconventionaldigitalcounterpart.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.135-143
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• 1998

Several equalizers are applied to the DVD-ROM(Digital Versatile Disc-Read Only Memory) system. Because imperfect writing process may cause nonlinear distortion in the reply signal, neural equalizers which have strong nonlinear mapping capability are applied to the system to compensate the nonlinear distortion. Experimental results to verify that the combination of decision-feedback type equalizers and modulation code is formidable are also given. The experimental results shwo that the SNR gain of the neural equalizers over the conventional equalizers becomes much as the nonlinearity in the channel increases. Furthermore, the decision-feedback type equalizers outperform the equalizers which have no decision-feedback in eliminating ISI(Intersymbol Interference) of random data sequence but there is no performance gain of the decision-feedback type equalizers over the equalizers without decision-feedback when these are applied to compensate the ISI of modulation-encoded data sequence.