Patent attributes
A partial response Class 4 detector in a recording and retrieval system and method of operating the detector for correcting the timing error of the detector. The detector includes a sequence table and comparison circuitry for comparing a sequence of data samples that includes previous and subsequent data samples with allowed sequences determined from the sequence table. When the sequence is an allowed sequence then there is high likelihood that data sample is correct, and the timing error for the data sample is determined in the phase error estimator and is corrected for. Otherwise, no correction is made for the timing error. In the preferred embodiment of the invention the coordinates of the sequence table correspond to the data samples, and the slope of the data stream at the data sample is stored in the sequence table. This reduces the size and increases the speed of the phase error estimator since the slope is now provided to it from the sequence table and it does not need determine the slope.
