A study on 3-level decision feedback Viterbi equalizer to (1,7) code at the optical disk recorder

Abstract

For application to recording code and equalization detection suitable for optical disk recorders, we discuss an algorithm for 3-level adaptive DF Viterbi equalization that is a combination of the (1,7) code with 3-level preequalization and RAM-DFE (decision feedback equalization) + Viterbi decoding. Its characteristics are evaluated by simulation. At a BER (bit error rate) of 10−4, the 3-level DF Viterbi equalization is found to exhibit characteristics 0.6 dB better than those of the 3-level 4-state Viterbi decoding for (DFE = 2, Viterbi = 4) and between 0.6 and 0.8 dB better for (DFE = 3, Viterbi = 4). Data recorded and regenerated at a shortest bit length of 0.32 μm and a track pitch of 0.6 μm in land group recording are used to confirm that the convergence of the 3-level DF Viterbi equalization is complete at 1.5×105 clocks with a modification coefficient of 4 and at 3×105 clocks with a modification coefficient of 64, and that the BER is about two-thirds of that for 3-level 4-state Viterbi decoding. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(8): 27–32, 1999