Information rates for magnetic recording channels with peak- and slope-limited magnetization

A model for magnetic recording is proposed which uses two parameters to describe the limitations on the remanent magnetization in the medium: the dimensionless peak value A_m and the steepest slope B(s^-1). A low-pass bandwidth restriction W(s^-1) due to read circuits is also included. Lower and upper bounds on the achievable transmission rates are derived in terms of the signal-to-noise ratio. For the case of ideal low-pass restriction with B≪W, the bounds increase linearly, logarithmically, and as the cube root, with low, medium, and large ρ_B, respectively. With B≪ W the problem reduces to the one with no restriction on the slope