Decoder and memory unit for optical disc drive

摘要

The decoder unit receives data from a recording medium (10) via two phase-locked-loops (PLL) (13,14) operating at similar frequencies. Pulse width modulated signals are recorded on the recording medium and coded (6) in a predetermined modulation code, generating a sample with a DC component. The first store, stores a dataset with positive polarity via the first PLL. The second store, stores a dataset with negative polarity via the second PLL. Both the positive and negative datasets are then delayed. A further data store receives the delayed data and the control unit controls the read/write timing.