[OPTICAL REVIEW Vol. 4, No. 3 (1997) 376-384]
An Advanced Signal Processing Technique Designed for Multilevel Signal Optical Disc System
Seiji KOBAYASHI* and Toshihiro HORIGOME
Optical Media Laboratory, Advanced Development Laboratories, Sony Corp., 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo, 141 Japan
(Received December 16, 1996; Accepted February 26, 1997)
We propose a novel signal processing technique by which we can increase the effective signal to noise ratio of optical discs. This technique is capable of reducing the influence of random noise even when the playback signal contains a distortion. We apply this signal processing technique to single carrier independent pit edge recording optical disc system. When a linear recording density of 0.2 ・ｵm/bit and a track pitch of 0.8 ・ｵm for an optical pickup is used in a DVD pickup (λ=635 nm, NA=0.6), the experimental results show that the system can obtain tangential and radial skew margins of ・ｱ0.5・ｰ and ・ｱ0.75・ｰ, respectively. From the experimental results, we estimate that the proposed method is capable of increasing the capacity of DVD by a factor of about 1.2.
Key words : optical disc, multilevel signal, trellis-coded-modulation, pit edge recording, sampled format, adaptive equalizer, signal processing, single carrier independent pit edge recording, noise