Superposition in inductive and magnetoresistive readback

This letter demonstrates that the physics of linear readback in various recording-reproducing systems is different from that of communication systems and conventional linear filters, in which superposition is described by the convolution integral. In a linear system of magnetic readback with inductive heads, superposition is described by the correlation (not convolution) between two vector entities-the derivative of media magnetization and the sensitivity function of the readback head. More generally, superposition in all linear magnetic readback with heads of any type is described by the correlation between two scalar entities-the distribution of magnetic charges in the recorded media and the scalar sensitivity function of the readback head with respect to moving charges.