Multi-level Run-length Limited Research Articles

Bimodulation code for signal waveform modulation multilevel optical disc

A new method for implementing a multilevel run length limited (ML-RLL) modulation code used in a signal waveform modulation multilevel (SWMM) optical disc, termed bimodulation code (BMC), is proposed. BMC is implemented with two steps: run length modulation and level modulation. A code rate of 5/6 BMC is realised, and the code efficiency reaches 94.47%. The parameter user bits per 400 nm of the presented code is 1.96, which is 30.7% more than that of EFMplus code used in a DVD system.

新型多阶只读光盘的差分相位检测信号分析

To improve the tracking servo performance, a novel signal waveform multi-level (SWML) read-only disc realized on the digital versatile disc (DVD) platform is presented. The characteristic of the differential phase detection (DPD) signal of the SWML read-only disc is analyzed both in theory and experiment. The amplitude of the DPD signal of the SWML read-only disc in an open tracking servo loop is about 2/3 of that of the DVD read-only disc. The uniformity and symmetry of the DPD signal of the SWML read-only disc are similar to those of the DVD read-only disc and better than the former multi-level run-length limited (ML-RLL) read-only disc.

Construction of Capacity Achieving $(M, d, \infty)$ Constrained Codes With Least Decoder Window Length

We present capacity achieving multilevel run-length-limited (ML-RLL) codes that can be decoded by a sliding window of size 2.

New Rate 6/9 Run-Length Limited (2, 11) Code with Spaced Pits/Lands Constraint for Four-Level Read-Only Optical Disc

Multi-level run-length limited (ML-RLL) modulation is a novel way to significantly increase the recording density without changing the optical or mechanical units of current optical disc systems. In this paper, a new rate 6/9 RLL (2, 11) code with spaced pits/lands (SPL) constraint is designed for four-level read-only digital versatile disc (DVD). The SPL constraint is used to obtain alternate multi-level pits and lands on the disc, and reduce the difficulty of multi-level disc replication. Compared with the former four-level SPL-RLL code with the same code rate, this new code has smaller size of decoding window and smaller parameter k.

Timing Recovery Method for Multilevel Run-Length-Limited Read-Only Disc

A novel timing recovery method for multilevel run-length-limited read-only disc is described. This timing recovery system employs interpolation method, which extracts multilevel run-length limited (ML-RLL) data directly from asynchronous oversampling RF data. The timing recovery system in the proposed read channel has a feedback architecture and consists entirely of digital circuits. It uses Viterbi detector output to calculate the phase error feedback to interpolator, and a special sync pattern is inserted to help frequency detection. The experimental results show that the acquisition time is much smaller than conventional timing recovery system.

Modulation principles and code design for multilevel optical data storage

Multilevel optical data storage is an important technology to improve the recording density of optical disc without changing the optical parameters. One approach is multilevel amplitude modulation, which uses the variance of signal amplitude of length-fixed recorded marks to record information. Another one is multilevel runlength-limited (RLL) modulation, which records information in both the signal amplitude and the length of recorded marks, thus can improve the recording density more effectively than the first way. Multilevel RLL coding is a key technology in multilevel RLL modulation optical recording. In this paper, a new 8-ary (1，3) RLL code is designed with state splitting algorithm. The recording density of this code is as high as 3.0 bits/symbol, and the encoder/decoder is simple and easy to implement. The proposed code can be used for future high density multilevel RLL modulation optical disc systems.

A Viterbi Detector with Feedback Used in Multilevel Run-Length-Limited Modulation Optical Recording

The multilevel run-length-limited (ML-RLL) modulation recording can improve the capacity and the data transfer rate of the optical disc without changing the optical and mechanical units. A viterbi detector with feedback is used to improve the performance of the partial-response maximum likelihood (PRML) system for ML-RLL optical recording. It can avoid the complexity of viterbi detector caused by the overlength of the memory length of the partial-response mode. The principle, implementation and the simulated results of the viterbi detector with feedback used in ML-RLL system are all presented.

Analysis of the Differential Phase Detection Signal in Multi-level Run-Length Limited Read-Only Disk Driver

Multilevel run-length-limited (ML-RLL) recording technology could be employed to increase the capacity of the read-only disc without changing optical and mechanical units. In this paper, the tracking error signal (TES) of differential phase detection (DPD) for ML-RLL digital versatile disk (DVD) read-only disk driver is analyzed in both theoretical and experimental way, the uniformity and symmetry of which are worse than that of the DVD read-only disk driver. The variation of peak to peak (PP) value distribution of the DPD signal in open loop of ML-RLL DVD read-only disk driver is about 2.6 times of that of the conventional DVD driver while the asymmetry is about 4 times. It is predicted that some improvements of the tracking servo system are needed in ML-RLL system.

Multilevel Run-Length Limited Recording on Read-Only Disc

Multilevel run-length-limited (ML-RLL) recording technology is employed to increase the capacity of the read-only disc with no change on optical or mechanical units. 4L-RLL recording on read-only disc has been implemented with minimum recorded mark length same as that in conventional digital versatile disc (DVD). The capacity of a double layer DVD disc with 4L-RLL (2, 10) modulation reaches 15 GB. Experimental results show that the ratio of the standard deviation of noise to the dynamic range of readout signal amplitude is lower than 4.53%, which means that the requirement of signal detection for 4L-RLL can be satisfied.

Study of multi-level run-length limited photo-chromic storage

Multi-level run-length limited (ML-RLL) storage is a novel method to increase the recording density and data transfer rate without making changes on optical pickup head. The storage mechanism and experimental system of ML-RLL photo-chromic storage are presented. The mathematical model of ML-RLL storage using photo-chromic materials is proposed. The nonlinear relation between the reflectivity of marks and the exposure power and time is reflected in this model. Based on the model, a proper write strategy used for 4-level run-length limited (4L-RLL) photo-chromic storage is obtained. Then a 4L-RLL photo-chromic dynamic experiment is carried out on 650nm photo-chromic material. Experimental results show that the 650nm photo-chromic materials used in the experiment can be used for ML-RLL storage and the recording channel can be effectively linearized by using proper write strategy, so the conventional signal processing techniques used for linear system can be used.

PRML process of multilevel run-length-limited modulation recording on optical disc

We introduce partial-response maximum-likelihood (PRML) signal process to increase the accuracy of reading multilevel signal from a multilevel run-length-limited (ML-RLL) recorded disc. The reason is that the traditional slicer detection is no longer suitable for detecting ML-RLL signal. In this paper, we also present several partial-response methods and their corresponding maximum-likelihood sequential estimation (MLSE) rules for ML-RLL modulation signal detecting.