Yoshihiro Okamoto

A study of PRML systems for perpendicular recording using double layered medium

The influence of jitter-like noise on the performance of PRML systems in the perpendicular magnetic recording channel using a double layered medium is studied. Both the bit error rate (BER) performance and the required SNR to achieve a BER of 10/sup -6/ are obtained by computer simulation and exhibit good performance even for the channel in which the power ratio of jitter-like noise to white noise is fifty-fifty.

Performance of PRML systems in perpendicular magnetic recording channel with jitter-like noise

Abstract The performance of PRML systems in a perpendicular magnetic recording channel using a double-layered medium is evaluated. The required SNR to achieve a BER of 10−4 is obtained by computer simulation. PRML systems hich provide good performance in the perpendicular magnetic recording channel with the various power ratios of jitter-like noise to white noise are shown.

Ber performance of PRML systems for perpendicular recording using single layered medium

The bit-error rate (BER) performance of perpendicular magnetic recording using a single-layered medium is studied. 16/17 (0, 6/6) code is adopted as a recording code, and is combined with various PRML systems to achieve higher linear recording density. The results of read/write experiments using a spinstand system show that the higher-order PRML systems such as E/sup 2/ PR4ML and E/sup 3/ PR4ML systems exhibit good BER performance in the investigated PRML systems.

Error event analysis in perpendicular magnetic recording using double-layered medium

Abstract The error events for PR2ML system in perpendicular magnetic recording using double-layered medium with additive white Gaussian noise, jitter-like noise and distortion due to low frequency cut-off are studied. The result shows that the error event “+−+00” extremely increases as the cut-off frequency becomes high. The error events obtained by computer simulation are also compared with those obtained by the R/W experiments. It is clarified that the simulated error events approximately correspond to the experimental results.

The rate 19/20 trellis code matched to enhanced extended class-4 partial response channel

In this paper, a rate 19/20 trellis code matched to the partial response (PR) channel is presented. Our trellis rode is designed on a multidimensional Euclidean space for which the minimum free Euclidean distance is larger than conventional recording codes. By using this trellis coding, a trellis coded partial response (TCPR) system is defined for the enhanced extended class-4 partial response (E/sup 2/PR4) channel. Further, the decoding method for this TCPR system is based on the syndrome-former trellis decoding. The number of add-compare-selects (ACSs) in our system is fewer than that of conventional Viterbi decoding. The result shows that TCPR system employing this rate 19/20 trellis code with the constraint length 7 for the E/sup 2/PR4 has an excellent performance compared with the conventional 8/9 maximum transition run (MTR) coding system in high-density recording.

MTR coded PRML systems for perpendicular magnetic recording

Abstract We evaluate the BER performance of various MTR coded PRML systems characterized by the polynomials with only positive coefficients in a perpendicular magnetic recording channel using a double-layered medium with jitter-like noise by computer simulation. The results show that 3 4 MTR coded PRML systems exhibit good performances compared with 16 17 MTR coded PRML systems.

A study of timing recovery for perpendicular magnetic recording

Abstract Performance of a timing recovery system for perpendicular magnetic recording channels is studied. The system detects timing error from pre-equalized waveform of a basic PR system such as PR1, and corrects the timing of sampled sequence using an interpolated filter. The results show that the system which uses PR1 system as the pre-equalization and directly compensates the reproduced waveform exhibits good performance.

PRML Systems Using Neural Network Canceller.

A neural network canceller has been applied to the PR4ML channel with partial erasure. First, a model of the read/write channel with partial erasure and the neural network canceller are described. Then, the bit-error rate of the PR4ML channel is evaluated by computer simulation and the performance is compared with that of a conventional neural network equalizer and a Nyquist equalizer. The results show that the neural network canceller exhibits better performance than the conventional neural network equalizer and Nyquist equalizer.

BER Performance of PRML Channel Using Single-Layered Perpendicular Medium

The bit-error rate (BER) performance of perpendicular magnetic recording using a single-layered medium is studied is studied. 16/17 (0, 6/6) code and (1, 7) RLL code are adopted as a recording code, and respectively combined with various PRML systems to achieve higher linear recording density. The results of read/write experiments using a spinstand show that the higher-order PRML systems such as E3 PR4ML and E4 PR4ML systems exhibit excellent BER performance.