Theoretical Study of the Overwrite Spectra Due to Hard-Transition Effects

Abstract

We have studied theoretically the impacts of the hard- transition position-shift efffect and the hard-transition shape-change effect on the readback signal spectra in an overwrite environment. Starting from first principles, we have shown that, in a typical overwrite situation, where a lower frequency CW (continuous-wave) background pattern is overwritten by a higher frequency CW data pattern, the hard-transition effects produce sidebands that are centered around the even harmonics of the data frequency. Moreover, the distances from the peaks of a sideband to the center of the sideband are given by the odd harmonics of the background frequency. Also, we have shown that the amplitudes of the peaks in these sidebands are given by simple analytical expressions. The results of our theoretical work were verified by comparing theoretical predictions with numerical simulations of the hard-transition shift effect, and with experimental data. In both cases, good agreement was obtained. © 1989 IEEE