Theory and practice of multilevel method in high-definition discs

Abstract

Multilevel storage is the easiest two-dimensional storage technology. On the basis of recording and read-out optical system of Digital Versatile Disc (DVD), by the method of multilevel run-length coding, the storage capacity can be increased by 60 percent of DVD9's, reaching 14 Giga Bytes.In order to meet the requirement of a 10 -4 raw Bit Error Rate (BER) of data readout, this paper presents a method of multilevel run-length coding with changeable level numbers. This method can take advantage of run-length redundancy to the utmost and reduce Inter-Symbol Interference (ISI) caused by multilevel run-length. Multilevel run-length coding uses the method of two steps modulation. This paper introduces a coding method of DK (1, 9) and R=1 code rate.Realized by Pulse Width Modulation, multilevel run-length modulation coding with changeable level has good symmetry. Its readout characteristics are the same as that of DVD with normal run-length modulation, therefore the servo control system needn't be changed. Also the signal can be recognized in two aspects respectively, run-length and level. In the sample disc, average raw BER in the two aspects is less than 10 -3 .Multilevel run-length modulation coding could be applied in various systems of run-length modulation coding. On the basis of the structure and characteristics of the primitive system, the comprehensive efficiency of coding could be increased by 33 to 50 percent.

New Differential Phase Detection Method for Signal Waveform Modulation Multi-Level Discs

“…1,2) Recently, a novel ML method called signal waveform modulation recording technology has been presented and researched. 3) The signal waveform modulation multi-level (SWML) readonly disc is implemented on the digital versatile disc (DVD) platform. 4) Figure 1 shows an atomic force microscopy (AFM) image of the SWML read-only disc.…”