Generalized method for measuring read-back nonlinearity using a spin stand

A new method for measuring the read-back transfer function of a magnetic recording system is proposed. For this method, square wave patterns are recorded over a range of linear densities. The resulting read signals should exhibit certain superposition properties if the read process were linear. The transfer function of a magnetoresistive (MR) head distorts read-back signals and makes the read process nonlinear. The inverse transfer function is modeled using an arbitrary function such as a polynomial or cubic spline. This model is then used to linearize the distorted read-back signals. Superposition properties are used to evaluate the accuracy of this correction and optimize the parameters of the model. The transfer function is then obtained directly from the optimum inverse transfer function. The effectiveness of the proposed method is confirmed by comparing the read-back transfer function obtained experimentally using this method and a MR read head with a direct measurement of the transfer function of the same read head. (C) 1997 American Institute of Physics.