A technique for measuring nonlinear bit shift

A novel method for measuring the bit position shift induced by neighboring transitions, known as nonlinear bit shift, is developed. The technique is based on special bit patterns which do not contain a specific frequency component when written without nonlinear bit shift. The presence of nonlinear bit shift will result in the appearance of this component and the amount of bit shift can be determined from its intensity. In the present work, a pattern that is insensitive to disturbances from certain unwanted effects such as the hard-transition shift, the positive-negative write current asymmetry, and the magnetoresistive head positive-negative readback asymmetry is used. Experimental results from the proposed method are in good agreement with those obtained by measuring pulse positions in the time domain