Apparatus for recovering data recorded on a magnetic storagemedium.

摘要

A data recovery apparatus comprises means (12) for measuring the phase difference between an input data signal and a reference data clock signal, means (13, 14) responsive to the phase difference to vary the frequency of the reference data clock signal so as to reduce the phase difference, and means for combining the input data signal with the reference data clock signal to produce a standardised output signal. The phase difference measuring means comprises means for producing a control signal indicative of a potentially uncorrectable phase difference error, and means responsive to the control signal for shifting the phase of the input data signal in time relative to the phase of the reference data clock signal before measuring the phase difference.