IMPROVED TIMING RECOVERY FOR SYNCHRONOUS PARTIAL RESPONSE RECORDING

摘要

An improved timing recovery phase-locked loop in a partial response recording channel comprising a means (52) for generating a frequency error and a means (54) for generating a phase error represented by a timing gradient DELTA t. The frequency error is not affected by a DC offset in the input reference signal and is less susceptible to noise due to an increase in sensitivity. A state machine (92) for generating expected samples is used to generate the timing gradient DELTA t, rather than estimated signal samples, which results in a shorter acquisition preamble. When tracking arbitrary user data, the timing gradient DELTA t is smoothed to reduce variations in the gain of the loop.