Patent ID: 7864895
Filing Date: 2011-01-04
Classification: G11B

Abstract:
1. A method comprising: obtaining an output signal sequence from a partial response channel, the output signal sequence comprising a waveform of widely varying amplitude; determining an input sequence of the partial response channel by maximizing cross-correlation of an estimated output sequence with the obtained output sequence, the estimated output sequence being estimated based on the partial response channel; and providing an output corresponding to the determined input sequence; wherein said determining the input sequence comprises employing Viterbi detection using a cross-correlation branch metric, the Viterbi detection providing a robust tolerance of phase uncertainty with the waveform of widely varying amplitude including providing accurate detection decisions even when the amplitude of the waveform is very small; and wherein the partial response channel has a transfer function defined according to a target polynomial, T(D)=p wherein when there is uncertainty about the gain of the partial response channel, the target polynomial is scaled by a gain factor, and said determining ignores the gain factor.