An Improved Approximation for the Isolated Transition in Saturated Magnetic Recording

INTRODUCTION I T IS APPARENT that an accurate description for the characteristic pulse shape derived from a single magnetic transition region is needed to be able to successfully model the high density behavior of the magnetic medium through the use of linear superposition. The validity of linear superposition is a prerequisite for the successful application of linear postequalization (receiver equalization) necessary to combat the effects of intersymbol interference and noise. Morrison and Speliotis [ 11 report this range of validity to go up to 60 000 bit/in (27 000 bitlcm), a packing density beyond reach of current technology. Other authors have suggested that this figure is too high, but the alternative to superposition is the Dynamic Hysteretic Model [2] -[4] . This method, though more accurate than superposition, particularly a t very high packing densities, involves a much greater computational effort and therefore was not considered in this study. Within the context of linear superposition, it is demonstrated that the readback voltage of the isolated transition can be approximated by a quartic function which in turn leads to a more general representation of the traditional arctangent magnetization pattern.