Our team have proposed and implemented a new type of multi-level DVD, which features in using the waveform to
differentiate levels. Servo accuracy is an important issue for an optical disk system, since it can directly influence the
quality of readout signal. This paper analyses the influence of servo error on the readout signal for our multi-level DVD
using numerical simulation. A readout model is established, where focus error (FE) and tracking error (TE) is introduced.
A new parameter, waveform deviation, is proposed to quantitatively evaluate the influence. Simulation results show that
the influences of TE/FE on readout signal are similar. Each of them will shrink the dynamic range of readout signal.
When TE/FE exceeds a threshold, the waveform deviation will increase sharply.
A novel design of physical format coding system (PFCS) is presented based on Multi-level read-only memory disc (ML
ROM) in order to solve the problem of low efficiency and long period of disc testing during system development. The
PFCS is composed of four units, which are 'Encode', 'Add Noise', 'Decode', 'Error Rate', and 'Information'. It is
developed with MFC under the environment of VC++ 6.0, and capable to visually simulate the procedure of data
processing for ML ROM. This system can also be used for developing other optical disc storage system or similar
channel coding system.
Nowadays, OMNERC research group is going to advance the capacity to 15GB by reducing the 3T pit length and
increasing the level of long pit based on the signal waveform modulation (SWM) ML recording technology. In order to
prove this method is realizable, this paper proposes the restriction points of consideration to reduce the minimum pit
length which influence the basic specification design of multi-level disk and the difficulty of the following signal
processing. Firstly the restriction of optical pick-up resolution is considered. Secondly, the restriction caused by read-out
channel is discussed in the paper. At the same time as write strategy has its limit based on the previous research, this
paper finally discuss the influence caused by minimize shortest pit length for level design of long length pit.
This paper principally analyses the influence of the DVD traverse manufacture and assembly error to the servo system, presents a specific servo system applied for DVD traverse tester, which is a digital servo based on general DSP. The repetitive control scheme is adopted to enhance the robustness to the periodic disturbance.