Media design for user density of up to 3 bits per pulse width

It is noted that increasing the user density in digital recording by the use of linear equalization and sequence detection will provide new design opportunities and new constraints on the recording media. The authors have evaluated five head/media designs to determine how the media can benefit from systems operating at higher user density. They conclude that the limits to recording at high user density are nonlinearities in dibit amplitude and increases in the dibit amplitude jitter and correlation. The origins of the nonlinearities and noise are described by knockdown and recoil of the media magnetization. Head/media systems must be designed to avoid knockdown. The systems which will be the most successful in taking advantage of new channel techniques will be system using high-efficiency codes with multiple bits per flux change.<>