Effects of the writing process and crosstalk on the timing accuracy of pulses in NRZ digital recording

The position at which a NRZ transition is recorded is dependent on the write current, the effect of increasing the current being to shift the recorded position beyond the trailing gap edge. The shift is more marked with a thick medium than a thin coating, and is worsened if the write head pole tips are approaching saturation. If the recording field changes magnitude when reversed, positive pulses become displaced relative to negative, and pulse pairing occurs. When recording different patterns on adjacent tracks, peak shifts can occur due to writing crosstalk aiding or opposing the head field and the shifts may well impose an upper limit to track density.