A Simple Model for Optimal Read Width Due to Finite Write Width and Offtrack Interference

With increasing recording areal density, the read width needs to be continuously reduced. For a given density, a narrower reader is preferred because of the reduced side reading from residual old information and adjacent tracks. On the other hand, for the written track, better crosstrack averaging and, thus, a higher signal-to-noise ratio (SNR) comes with a wider reader. As a result, an optimal read width exists for a certain recording system. In this paper, a simple estimate of SNR is presented that includes the effect of the finite widths of the reader, the written track, as well as the offtrack interference. The optimal read width is obtained by maximizing the SNR value with a different read width. The effect of read width on offtrack capability, SNR to written track width sensitivity, and the impact of the shape of the microtrack profile will also be discussed. A comparison with an experiment shows good agreement between measurements and calculations.