Performance Evaluation And Improvement Of Optical Disc Used Modulation Code Based On Power Spectrum Analysis

In optical disc system, the performance of channel code has a great impact on channel performance, which is one of the factors requiring careful consideration in optical disc standard. Run-Length Limited code is one of modulation codes which is widely used in optical disc system. Power spectrum is an important aspect in evaluating performance of modulation code. Therefore, the study of spectral performance of modulation code has great significance.On the basis of introducing the theories of Run-Length Limited code briefly and analyzing basic model and technology of optical recoding channel, the power spectrum computation methods of three different Run-Length Limited sequences have been studied, and their advantages and disadvantages have been analyzed. The method which is based on one step state-transition matrix is proposed to be used to compute practical Run-Length Limited code. With the implementation of the power spectrum computation method based on one step state-transition matrix, the power spectrums of 3PM Look-Ahead code and EFMPLUS code are computed in order to validate the effectiveness and correctness of the method.In Next-Generation Versatile Disc, RLL(2,12;8,15)code and RLL(1,10;4,6)code with independent intellectual property rights are used as optical channel code, In respect to the two code, the method based on one step state-transition matrix is used to analyze the power spectrum of the codes respectively, and the implementation procedures are presented. The spectrum performance analysis of the Run-Length Limited code is focus on the low-frequency component suppression and the transmission efficiency on every the frequency. On the basis of above, the code is improved in order to get a better spectrum performance. According to the comparison of power spectrum, the spectrum performance of improved code is better than that of original code.