Multichannel signal processing for multiple-head digital magnetic recording

This paper analyzes the performance of a multiple-head, digital, magnetic recording system using multichannel signal processing theory. A multi-input, multi-output (MIMO) channel that models the multiple-head recording process provides the basis for this analysis. This model characterizes the write process, the read process and both electronics and media noise. In particular, the model accounts for side fringing between a read head and adjacent tracks; side fringing is a major cause of intertrack interference that is often neglected during signal processing analysis. Optimal decision feedback and partial response equalizers for the MIMO channel are derived using a minimum mean-squared error criterion. Numerical evaluations show that a magnetic recording system comprising a multiple-head array and equalizer combats intertrack interference much better than does the corresponding single-head system. As a result, the multiple-head system achieves a gain of up to a factor of 3.5 in radial density over the single-head system for a fixed value of maximum head misalignment