A Survey Of Adaptive Equalization For Magnetic-disk Storage Channels

Abstract

This paper surveys the use of adaptive equalization to increase the density, as well as reduce the manufacturing costs, of commerical magnetic-disk storage systems. We list some of the most important characteristics that must be considered by the adaptive equalization designer in ap- plying equalization and adaptive filtering methods to the magnetic disk storage system. Specifically, we survey the important problems of radial channel variation, offtrack ef- fects, channel nonlinearity, and datadependent noise, and discuss their effects upon conventional equalization meth- ods. We then describe modifications of these conventional equalization methods that can be used to design an adap- tive equalization system that is appropriate for disk storage systems.