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 SNRWG. 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.