Read channel with turbo decoding for magneto-optical disks

Blue lasers are indispensable for high-density recording on magneto-optical (MO) disks. Since the sensitivity of photodetectors decreases for blue laser light, it becomes difficult to obtain a sufficient signal-to-noise ration (SNR) for the MO readout signal. Turbo codes can provide a significant coding gain for both optical disks and magnetic disks. In this study, we used computer simulation to investigate the performance of turbo decoding for MO disks. We then develop a Verilog-HDL module based on our simulation results. The performance of turbo decoding was confirmed experimentally by evaluating the bit error rate for real MO readout signals as compared with the partial response maximum-likelihood (PRML).