Modulation Code and PRML Detection for Multi-Level Run-Length-Limited DVD Channels

Multi-level run-length-limited (ML-RLL) modulation on optical storage channels is a promising method to increase the recording density effectively. In this paper, some experimental results of 4-level RLL modulation on digital versatile disc (DVD) read-only discs are firstly presented. A new DC-free 4-ary RLL (2.8) code with code rate of 8/10 (bits/symbol) is designed, and partial-response maximum-likelihood (PRML) detection is used to evaluate the bit error rate (BER) performance of multi-level readout signals. Experimental and simulation results show the feasibility of 4-level RLL modulation on DVD channels