Timing Recovery Method for Multilevel Run-Length-Limited Read-Only Disc

A novel timing recovery method for multilevel run-length-limited read-only disc is described. This timing recovery system employs interpolation method, which extracts multilevel run-length limited (ML-RLL) data directly from asynchronous oversampling RF data. The timing recovery system in the proposed read channel has a feedback architecture and consists entirely of digital circuits. It uses Viterbi detector output to calculate the phase error feedback to interpolator, and a special sync pattern is inserted to help frequency detection. The experimental results show that the acquisition time is much smaller than conventional timing recovery system.