Abstract

Multilevel recording technology is used to improve the recording density without changing the optical and mechanical units. A new modulation code scheme for signal waveform modulation multilevel (SWM) read-only optical disc has been implemented. The proposed scheme is composed of run-length limited (RLL) modulation and level modulation two steps. RLL modulation is employed to meet the requirements of channel. To acquire higher code rate, the parameter d of RLL(d, k) is decreased to 0, which makes the presented scheme difference from other modulation codes of the optical storage systems. Increasing the number of k also contributes to the high code rate. Decreasing d and increasing k will respectively introduce more inter-symbol interference (ISI) and timing recovery error (TRE) to SWM optical system. Level modulation is used to resolve these problems. The decoding rule is simple and easy for implementation. The signal waveform of SWM disc adopted the proposed code is also described. The information bits per 400nm are 2.19, which is 46% higher than that of DVD.

© 2009 SPIE