Hideyuki Yamakawa

PERD: partial error response detection

Extended Partial Response Maximum Likelihood (EPRML) detection outperforms PRML detection on very high-density magnetic recording channels but is much more complex than PRML and is difficult to implement for high data rates. PERD is an alternative to the EPRML detector which gives even better performance. It consists of a conventional PRML detector and a pattern discrimination circuit operating on the error waveform between the waveform estimated from the PRML outputs and the actual playback waveform. A bit-by-bit simulation confirms the expected performance gains over PRML detection.

Performance evaluation of asymmetrical run-length-limited code for optical disks

A performance comparison between a rate 8 / 14 asymmetrical run-length-limited (RLL) code and the EFMPlus code for optical disks is described. The limited condition of the rate 8 / 14 asymmetrical code is. This code has a better detection window size than the EFMPlus code because of the 14.3 percent greater efficiency of its coding rate. We describe the bit error rate (BER) performance and the tilt and defocus tolerance of the rate 8 / 14 ARL code. Compared to the EFMPlus code, the rate 8 / 14 ARL code has a 0.7-dB gain in the required S / N at a BER of 10-4. The rate 8 / 14 ARL code is also more robust against tilt and defocus.

Rate 8/14 asymmetrical DC control code for optical disks

A new run-length-limited (RLL) code for optical disks is described. It is a rate 8/14 asymmetrical (d1,d2,k)=(2,1,11) code that has a better detection window size. Compared to the EFMPlus code, the ARL code has a 1.6 dB gain in the required SNR at a BER of 10/sup -4/.