Pulse asymmetries and write non-linearities in the write equalization process

In this paper, we compare experimental measurements of magnetic tape record ing signals with the results of simulation. Specifically, non-linearities a ssociated with the write equalization process are examined. It is found tha t the depth dependent vector Preisach model (VPM) of the magnetic recording process is able to semi-quantitatively reproduce non-linearities that are seen in the readback from real heads and media. The failure of standard lin ear superposition models even qualitatively to capture these effects is dem onstrated. Furthermore, the VPM shows, through the recorded magnetization d istribution, that demagnetizing effects from the data transitions can disto rt the write equalization pulses, if the pulses follow the data transitions too closely, This leads to a directional asymmetry in the writing process, such that symmetrically placed write equalization pulses do not lead to th e most symmetrical waveforms.