多阶游程长度受限编码的光盘读出信号

多阶游程长度受限(ML-RLL)编码可以在保持原有记录符尺寸和记录单元数量的情况下将CD光盘存储容量提高2.4倍。借助标量衍射理论建立了多阶游程长度受限记录符的计算模型,对采用多阶游程长度受限编码的CD光盘的读出信号进行了仿真分析。结果表明,记录坑长度的变化对读出信号幅值影响较小,有利于将记录坑长度和记录坑的宽度两个参数进行分离检测,但在3T长度、不同宽度的记录坑相连的情况下,从读出信号中很难分辨出记录符的分界位置。

Readout signal of optical disc with multi-level run-length limited coding

Multi-level run-length limited(ML-RLL) cording can increase the capacity of CD to 2.4 times of the conventional CD.A model of ML-RLL recorded mark is introduced with scalar diffraction theory,and the readout signal of ML-RLL CD is calculated.It is recognized from simulation results that influence of the change of recorded mark length to the amplitudes of readout signal is little for ML-RLL recording.It is beneficial to separate detection of the width of the recorded mark from the detection of the length.But the boundary of recorded mark is difficult to distinguish for continuous 3T recorded marks with different widths.