Patent Document ID: 8582223
Application ID: 13363155
Patent Status: 1

Claim One:
1. A computer-implemented method of decoding data written over a plurality of tracks of a disk of a hard disk drive, comprising: selecting a mask configured to account for Inter-Symbol-Interference (ISI), the mask including channel coefficients and defining a trellis that defines a plurality of states; receiving a signal corresponding to an input pixel from each of the plurality of tracks, and generating equalized samples therefrom; computing transition branch probabilities for each input vector based on a Gaussian noise distribution using the equalized samples, ideal samples and a priori probabilities of the input vector; computing forward and backward probabilities via recursions using the computed transition branch probabilities for each of the plurality of states of the trellis; combining the computed forward probabilities, backward probabilities and the transition branch probabilities to generate a-posteriori probabilities for the input vector; marginalizing the a-posteriori probabilities over values of neighboring pixels to generate an a-posteriori probability for a pixel of the input vector in a given state, and decoding the pixel as a first logical state or a second logical state from the marginalized a-posteriori probabilities.