DC-Free Four-Ary (2,8) Run-Length Limited Code for Multi-level Recording Channels

Abstract

A new high efficient DC-free (2,8) run-length limited (RLL) code for four-level optical recording channels is proposed. The proposed code can be represented by a finite state diagram (FSM) with three states and implemented easily. The code rate and density ratio of the code are 5/6 bits/symbols and 2.50 bits/minimum-recorded-mark, respectively. On the basis of the experimental results, the performances of the code are evaluated by using partial-response maximum-likelihood (PRML) technology, which is suitable for detecting multi-level RLL signals. By using four-ary (2,8)RLL modulation and PRML technology, one can increase the recording density 66.7% relative to conventional binary RLL modulation currently used in digital versatile disc (DVD), meanwhile the bit error rate (BER) still be acceptable.

PRML Detection of Multi-Level DVD Channels with Run-Length-Limited Modulation

“…Therefore, PRML detection has been proposed to compensate the SNR lost and handle the ISI effect [24], [25]. Since the reduction of SNR in a multi-level optical disc system is rewarded by the increase of recording density, ML-RLL modulation achieves a good tradeoff between SNR and recording density [22].…”

“…Ref. [22] reduce the inter-symbol interference (ISI), and k is used for timing recovery. The choices of parameters d and k depend on various factors such as the channel symbol rate, the desired recording density, the detection window and so on.…”

“…However, most of these codes have large value of M > 4, and exceed the requirements of practical ML-RLL modulation systems. For ML-RLL modulation with M = 3 and 4, some new codes are constructed with different methods [19], [20], [21], [22]. Table I 0 1 0 1 1 1 0 1 1 0 0 1 1 1 0 1 0 0 2 0 0 0 0 1 0 0 0 2 0 0 0 3 0 0 1 0 0 0 2 2 2 2 2 3 3 3 3 1 1 1 1 0 0 0 1 DR values of M -ary RLL (d, k) codes are much higher than that of binary RLL codes.…”

Constrained Code and Partial-Response Maximum-Likelihood Detection for High Density Multi-Level Optical Recording Channels

“…are closer to the transfer function of the S ¼ 3:8 recording channel when normalized frequency is less than 0.25. However, as high frequency signals in multi-level RF signals are easy to be missdetected, 15)…”

Modulation Code and Signal Characteristics for Signal Waveform Modulation Optical Disc

“…The conventional modulation code used in binary optical data storage is the run-length-limited [RLLðd; kÞ] code, where d and k stipulate the number of zeros between two neighboring ones at least d and at most k. The M-aryðd; kÞ code 2,3) is developed for multilevel optical recording systems, such as the pit-depth modulation multilevel system 4) and pit depth and width modulation multilevel optical disc. 5) The parameter M denotes the level number, and d and k are the same as in RLLðd; kÞ.…”