GEN04-1: Cancellation of MR Head Asymmetry in Magnetic Tape Storage Systems

This paper describes a fully digital approach for pulse-asymmetry estimation and cancellation in magnetic tape storage systems that employ magneto-resistive (MR) read heads. Algorithms are presented for decision-aided and non-decision- aided estimation of pulse asymmetry. The cancellation of asymmetry is based on a quadratic model of the MR head non- linearity. Using read-back waveforms obtained from commercial tape drives, it is shown that a significant improvement in read-channel performance is achieved by the techniques described. Asymmetry estimation and cancellation using a specific pattern defined in the linear tape open (LTO) tape format are also addressed.