• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.336-342
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• 2003

Noise predictive maximum likelihood(NPML) detector embeds noise prediction/whitening process in branch metric calculation of Viterbi detector and improves the reliability of branch metric computation. Therefore, PRML detector with a noise predictor achieves some performance improvement and has an advantage of low complexity. This thesis random sequences are applied to linear channel. In perpendicular magnetic recording density KP=2.5, NP(121)ML and NP(1221)ML detection system which is based on a noise predictive PR-equalized signal are evaluated by the Performance through a computing simulation. Therefore, NPML systems are implemented and are verified by VHDL.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1034-1039
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• 2004

Since the major reason of the detection failure is from the consecutive data transitions, it is desirable to limit the MTR(maximum transition run) within two. Therefore, we propose a new MTR code that limits the MTR constraint to 2 and k-constraint to 8. In addition, DC-free coding is performed to overcome the media noise that exits in low frequency of perpendicular recording system. We use a GS (Guided Scrambling) for DC-free coding, and the performance of the code is compared with that of the rate 819 code used in the conventional recording channel by a computer simulation.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.279-280
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• 2008

In order to improve the performance and simplify the structure of the conventional detectors in high density magnetic channels, a new equalizer based on bilinear recursive polynomial (BRP) models, which uses the previously estimated sequence, is proposed. The performance is compared with the conventional equalizers and the maximum likelihood sequence detection (MLSD) bound.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.454-457
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• 2004

Partial response maximum likelihood (PRML) is a powerful and indispensable detection scheme for perpendicular magnetic recording channels. The proposed method is a low complexity detection scheme which is related to the PRML system. The simulation results show that PR(1,2,3,4,3,2,1)ML and PR(l,2,3,3,2,1)ML using modulation encoding with R=2/3 have the most improved performance at K=3,4. However, in the case of K=3, R=2/3 PR(1,1,1,1)ML effectively reduces the complexity compared to PR(1,2,3,3,2,1), but it has L5dB performance degradation at most. In the case of K=4, R=l PR(1,2,2,1)ML has very low complexity compared to R=2/3 PR(l,2,3,4,3,2,1)ML. but it has about 2dB performance degradation at most.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.15-20
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• 2009

For perpendicular magnetic recording (PMR) channels, noise-predictive maximum likelihood (NPML) detection method has been used. But, it is hard to expect improving the performance when the bit density is increased. Hence, we exploit the coding methods which has good performance. In this paper, we show the performance of the recursive systematic convolutional (RSC) codes with turbo-equalization method with different channel bit densities. The noise model is 80% jitter noise and 20% AWGN.