Abstract: A finite impulse response (FIR) filter and a Viterbi detector system for a magnetic read channel are disclosed. The FIR equalizer generates equalized sampled outputs to the Viterbi detector system. The Viterbi detector system determines the most probable value of all references, R.sub.i by accumulating a summation of data sample values, D.sub.t, for selected legal bit sequences over a significant amount of random data. The summation and count of data samples are output to a system microprocessor for calculation of an average reference for each path of the Viterbi system. The Viterbi detector system also calculates, in real time, magnitude of differences between the output data received from the FIR equalizer and transition references for each data sample to generate transition metrics, adds transition metrics to state metrics from the source node of two paths, and compares the result. The lesser of the two results yields the most likely correct state metric.

Abstract: In the system of the present invention, the system includes a pre-synchronizer to eliminate the need for examining every possible substring preceding the EOP (end of preamble) mark in order to detect the EOP. For the case where autocorrelation techniques are used to provide error synchronization error tolerance, this results in a much shorter EOP, since it is possible to find shorter EOPs which do not falsely synchronize prior to the arrival of the true EOP. In particular, the preamble is utilized to perform pre-synchronization. Once pre-synchronization has been achieved, the search for the EOP can be focused on a subset of all possible substrings as opposed to prior techniques which looked at all possible substrings. The resultant system solves the problem with less logic and more error tolerance.