Adaptive equalization using expanded maximum-likelihood detector output for optical recording systems

For high-density optical recording systems, the effectiveness of the partial-response maximum-likelihood (PRML) detection scheme is limited by the channel asymmetry. Hence, to solve the problem and improve detection performance, we present an adaptive equalization scheme using the output of an expanded maximum-likelihood (ML) detector, The proposed PRML detection method adapts well to the asymmetric optical recording channels and has better bit error rate performance than the conventional PRML detection method.