Signal processing and coding for M-ary optical storage

We introduce the theoretical and practical concepts behind M-ary signaling on optical recording systems such as compact disc (CD), digital versatile disc (DVD) and evolving next generation blue laser formats. We show that there is sufficient signal-to-noise ratio on all recording formats (ROM, R and R/W) and give examples of how density and data transfer rate can be improved by two to three times with no changes in disc media or recorder.