In one embodiment, a method includes passing a signal through an adaptive noise whitening filter, wherein one or more noise whitening coefficients used in the noise whitening filter are updated using a noise whitening filter coefficient updater, wherein the noise whitening filter is configured to process the signal according to a transfer polynomial: W(D)=1−(p1D+ . . . +pλ′Dλ′), where p1 . . . pλ′ are noise whitening coefficients, where a tape channel is characterized by a transfer polynomial F(D)=1+f1D+ . . . +fLDL where D is delay corresponding to bit duration, with 2L being a number of states of the tape channel, wherein a soft detector has a total of 2L+λ states, the noise whitening filter comprises 2λ′ states, λ′ is greater than λ, L represents a memory length of the tape channel, and λ represents a memory length of the noise whitening filter.