A novel sensitivity function for MR heads and an application

A two-dimensional sensitivity function, describing the down-track and cross -track responses of a MR head, is derived starting from a microtrack formed with a maximal-length Pseudo Random Binary Sequence (PRBS), This sensitivi ty function is built up from a set of 'Extracted Dipulse' responses each ta ken with the readback head in a different off-track position with respect t o the microtrack, The resulting two-dimensional function represents the sen sitivity to a 'unit magnet' with a length of one channel bit, rather than t o the vertical field component alone, There are two advantages to this appr oach: First, the sensitivity to high frequency signal components is much en hanced and the signals used are generally much more representative of writt en data. Second, this method has the ability to quantify both linear and no nlinear readback distortions as a function of off-track position, This pape r initially describes the practical; procedure used to obtain the sensitivi ty function. An advantage of this procedure is that you do not need to have a clock channel for the timing alignment of the dipulses as they are alrea dy tied to the bit-cell positions. In the latter half of the paper, this pr ocedure is used to analyze the effects of "read-write non-parallelism" a co ndition wherein, the MR stripe reads the transitions at a skew due to a man ufacturing defect or otherwise. In other words, it is probed whether a cros s-track variation in head sensitivity would contribute towards the so-calle d 'deterministic off-track peak jitter' and also whether a relative skew be tween read and write operations can influence the head sensitivity function and aggravate the deterministic peak-jitter, The answers we got for both t he questions were in the negative, There was no any deterministic trend in peak-position variation (as against the trends that we got with full-width tracks) with or without a skew and the head sensitivity function was also n ot affected by a skew.