Patent ID: 8760789

Claim:
A read channel comprising: a preprocessor for receiving a first signal and producing a second signal from the first signal using current values of a positive coefficient, a zero coefficient, and a negative coefficient; an interpolator for producing a third signal based on the second signal; and a slicer for producing a fourth signal from a third signal by estimating a level for the third signal, wherein: the fourth signal is at one of three levels consisting of a positive level, a zero level, and a negative level; for every n first signals received by the preprocessor, the current value of one of the positive coefficient, the zero coefficient, and the negative coefficient is adjusted depending on which of the three levels the fourth signal is at, and wherein the preprocessor produces the second signal from the first signal according to: γ o =γ i +K pos (γ i ) 2 +K zer if γ i >0, and γ o =γ i +K neg (γ i ) 2 +K zer otherwise; where: γ i denotes the first signal; γ o denotes the second signal; K pos denotes the positive coefficient; K zer denotes the zero coefficient; and K neg denotes the negative coefficient.