Patent ID: 7898756

Claim:
A disk drive comprising: a disk; a head actuated radially over the disk, the head operable to generate a read signal when reading a training data sequence recorded on the disk; a sampling device operable to sample the read signal to generate a sequence of read signal samples; an equalizer comprising a plurality of coefficients, the equalizer operable to equalize the read signal samples to generate a sequence of equalized samples; a sequence detector for detecting an estimated data sequence from the equalized samples, wherein the sequence detector operates according to a target response comprising a plurality of target values; and control circuitry operable to adapt the target values by: computing error values in response to a difference between expected samples and the equalized samples; computing a gradient in response to a correlation of the training data sequence with the error values; and adjusting at least one of the target values in response to the gradient, wherein the control circuitry is operable to compute the gradient in response to an error event of the sequence detector convolved with the target values of the target response.