Design Curves and Information-Theoretic Limits for Perpendicular Recording Systems

To optimize a high-density magnetic recording system, one needs to know the tradeoffs between various components of the system including the read/write transducers, the magnetic medium, and the read channel. In this paper, we consider a channel model characterized by three parameters: the replay pulse width T
₅₀
, the transition jitter noise standard deviation sigma
_J
, and the signal-to-electronic-noise ratio SNR
_WG
. We utilize information-theoretic tools to determine the acceptable region for the channel parameters T
₅₀
and sigma
_J
when optimal detection and linear coding techniques are used. This paper is an extension of a similar analysis for a system that utilized a minimum mean-squared error (MMSE) equalizer, a Viterbi detector, and a Reed-Solomon (RS) code. Our main conclusion is that there is a considerable potential gain to be achieved by using improved detection and coding schemes as compared with the present system