Advanced channels for DVD with d=2 modulation coding

Modulation codes with d>0 are essential in optical recording to enable useful densities, since the minimum mark size achievable is limited by the diffraction-limited spot size. The EFMPLus modulation code is a coding scheme adopted for the digital video disk (DVD). This is a run-length limited code with constraints d=2 and k=10. It is appropriate to exploit this knowledge of the coding scheme in the detection strategies, to sustain high performance at higher densities and data rates. This paper presents the performance of two simple equalizers, one of which uses decision feedback, to achieve a target response that enables optimal detection by simple thresholding. The evaluations are done using a channel model. Equalization strategies that exploit the d=2 RLL constraint in the DVD channel provide improved performance of about 2 to 4 db for the DVD specifications.