Phase equalization for perpendicular recording

Evaluation of perpendicular recording has been hampered by the unique pulse shape resulting from the perpendicular magnetization and the ring head. In this paper an equalization technique is presented which will allow traditional peak sensing without any code constraint. The Hilbert transform relationship of the perpendicular and longitudinal sensitivity functions of the head is exploited in the filter design. The readback pulse is converted from the sensed bimodal pulse to a unimodal pulse via a phase adjustment. Minimal signal-to-noise degradation occurs with use of this filter, providing the best comparison of transition widths for perpendicular and longitudinal transitions. The phase equalized pulses are significantly narrower than those experienced with longitudinal systems under the same conditions. Both simulated and experimental results are presented.