Error rate performance of TCPR system using turbo code for digital magnetic recording channel with partial erasure
Recently, it is widely known that the partial response maximum-likelihood (PRML) system has attracted much attention as one of indispensable signal processing technique for achieving high density digital magnetic recording. But, the performance of PRML system is degraded by many undesirable causes in recording channel. For improving the performance, it is desirable to use any high order PRML system or high rate code. Our proposed two-track recording method increases the coding rate over 1, and contributes to decrease these degradation effects. The recording code in our system adopts a turbo code which provides a substantial near-ML performance by the suboptimum iterative decoding algorithm. In this paper, the turbo coded Glass four partial response (PR4) systems using the rate 4/6, 8/10 and 16/18 codes for high density two track digital magnetic recording are proposed. The error rate performance of the proposed system is obtained by computer simulation taking account of the partial erasure, which is one of nonlinear distortions at high densities. The performance of our system is compared with that of the conventional NRZ coded PR4ML system. The result shows that the proposed system is hardly affected by partial erasure and keeps good performance in high density recording. In especial, the proposed system using the rate 16/18 turbo code can achieve a bit error rate of 10(-4) with SNR of approximately 12.2 dB less than the conventional NRZ coded PR4ML systems at a normalized linear density of 3.
tcpr system turbo code digital magnetic recording partial erasure iterative decoding