| 摘要 |
<p>Signals corresponding to the front edge and the rear edge of a pit of an optical signal are sampled and thereby a pair of signals Vx and Vy are obtained. Since two-dimensional decoders (41...48) map all combinations of the low order three bits of six bits of recorded data, they also decode the high order three bits of the recorded data. Estimated value calculating circuits (51...58) output estimated values Vx' and Vy' corresponding to the decoded outputs. Subtracting devices (61...68) and square calculating devices (71...78) calculate the distances (error powers) between real reproduced signals and estimated values. With a plurality of error powers that chronologically vary, a Viterbi decoding circuit (80) generates decoded output data. <IMAGE></p> |
