用於DVD讀取通道的PRML偵測器分析與設計

Abstract

在高密度的光學儲存系統上，碼際干擾(Inter-Symbol Interference)限制了資料讀取的可靠性。針對此一問題，我們採用部分響應最大近似技術(Partial Response Maximum Likelihood)來解決。在本論文中，我們首先針對DVD的讀取通道，建立一個部分響應通道模型(Partial Response Channel Model)，並藉用此模型來設計與分析一個完整的部分響應最大近似偵測系統。 針對最大近似偵測部分，我們選擇以威特比偵測器(Viterbi Detector)方式來實現。藉由在本論文中的分析和模擬，我們得知在各種條件下此偵測器的效能表現，並從中決定最佳的威特比偵測器設計參數。此外，對於部分響應最大近似技術在實現上所遇到的通道估測(channel estimation)和時序恢復(timing recovery)等瓶頸問題，在本論文中有詳細討論和分析。

In the high-density optical storage system, the effect of Inter-Symbol Interference (ISI) causes the unreliable data detection. The Partial Response Maximum Likelihood (PRML) technology is proposed to overcome the effect of ISI. In this thesis, we build a partial response (PR) channel model for the DVD read channel. Based on this PR model, we analyze and design a complete PRML detection system. The Viterbi detector is adopted to realize the maximum likelihood sequence detection. From the detailed system simulations, the performances of the PRML detection under various conditions are discussed. Based on these analyses, we can obtain the design parameters of the Viterbi detector to achieve the optimal performance. In addition, we also introduce and analyze the channel estimation and timing recovery in the PRML system, which are the bottlenecks of the PRML realization.