The erasure characteristics of longitudinal magnetic recording media have been explored by correlating measurements and the results of a magnetic recording simulation. The two-dimensional simulation uses the standard self-consistent method with a vector Preisach hysteresis model. Writing NRZI-All-1 patterns with a ferrite head at 1 MHz generates the unerased magnetization pattern. The simulated unerased voltage pulse shapes agree well with experiment. The Fourier harmonics of the readback waveform characterize the recorded signal, and are observed as a function of longitudinally applied dc and decaying ac erase fields. Results from experiment and simulation indicate that dc erase fields, of strength near Hc, enhance even Fourier harmonics of the NRZI waveform by destroying the antisymmetric relationship between successive pulses. The measured superiority of ac erasure is explained by both more rapid approach to demagnetization, and broadening of the transition.
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Wiesen et al. (1988) studied this question.
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