Abstract
ABSTRACT Multi-level run-length-limited (ML- RLL) modulation on optical storage channels is a promising method to in-crease the recording density eectivel y. In this paper, some experimental results of 4-level RLL modulation ondigital versatile disc (DVD) read-only discs are rstly presented. A new DC-free 4-ary RLL (2 ,8) code withcode rate of 8/10 (bits/symbol) is designed, and partial-response maximum-likelihood (PRML) detection is usedto evaluate the bit error rate (BER) performance of multi-level readout signals. Experimental and simulationresults show the feasibility of 4-level RLL modulation on DVD channels.Keywords: Multi-level optical storage, modulation codes, M -ary run-length limited codes 1. INTRODUCTION Multi-level optical recording can be used to increase the storage capacity of 2-3 times than that of conventionalbinary recording. 1 A lot of multi-level optical recording schemes have been developed such as the multi-levelamplitude modulation system developed by Calimetrics, which records 8-level signals on traditional compact discrecordable/rewritable (CD-R/RW) discs.
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