Design And Simulation Of PRML Read Channel Of Next-Generation Versatile Disc

The optical head recognizing signal detection is one of the core technologies of compact disc reading channel. The normalized information density of next-generation versatile disc (NVD) disc system is greater than or equal to 4.6. Due to the increasing disc storage density, the signal to noise ratio (SNR) decreases and the inter-symbol interference (ISI) between symbols increases, which reduces the data reliability. A large error rate would be caused by using the traditional peak detection method. It is possible to maintain high data accuracy, improve data storage density and data reading speed by applying the detection technology of partial response maximum likelihood (PRML) which is widely used in magnetic storage to optical storage, even when the ISI is terrible.Based on a brief introduction to the disc reading channel, channel processing and PRML technology, this thesis attempts to analyze the frequency features of NVD disc channel, choose the partial response polynomials 1 + 2 D + 2 D² + 2D³ + D⁴for the NVD disc channel with appropriate normalized information density 4.6, draw a corresponding state transition graph to partial response polynomials combined with RLL (2,12) modulation code, design the general framework for the NVD disc PRML channel, and introduce the design of partial response equalizer and Viterbi decoder in detail.Software is employed on a PC to build models for NVD disc PRML channel. This thesis focus on three sub-modules: NVD disc channel model, partial response equalizer, and Viterbi decoder. MATLAB and related software are used to simulate the NVD disc PRML channel model under the conditions of no noise and Gaussian white noise, and the simulation results are analyzed and compared. An oscilloscope is applied to implement the simulation test for the PRML channel with the signals collected from NVD optical head, and the test results are analyzed.The error rate of simulation is less than 10^-6 under the condition of SNR 15db, which means that NVD disc PRML channel based on software can achieve accurate function and good performance under the interference of Gaussian white noise.