| 摘要 |
A method and apparatus for the processing of magnetic recording data signals which provides for the cancellation of the effects of precursor intersymbol interference (ISI) in the data signals. According to one illustrative embodiment, an adaptive filter is used to produce a replica of the precursor ISI, which is then subtracted from a delayed version of the data signal. The amount of the delay is advantageously equal to the delay between the main peak of the channel impulse response and the leading undershoot (i.e., the precursor ISI effect) which is to be canceled. The signal which is provided to the adaptive filter (to produce the precursor ISI replica) may be based on tentative decisions generated by a symbol-by-symbol detector, and may first be converted from three levels to two levels by a three-to-two level converter. The resultant signal (after the aforementioned subtraction), which is essentially precursor ISI-free, may then be processed by a conventional Viterbi decoder to produce the decoded symbol data.
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