1-2hit |
Toshihiro UEHARA Keigo MAJIMA Shoichiro OGAWA Junji NUMAZAWA
We propose precise write-time compensation for nonlinear transition shift in magnetic tape recording using d=1 runlength-limited (RLL) code as a channel modulation. In this write-time compensation approach, the write current transitions having a transition within 3 bits earlier are shifted so as to minimize the transition shift of the readback signal. First, we precisely measured the nonlinear transition shift using a VCR. Next, based on this measurement, we simulated the effects of the write-time compensation, verifying them in recording experiments with a VCR. The results show that when the optimum read equalization is applied to the readback signal, this write-time compensation approach increases the eye height and eye width while improving the byte error rate by about two orders.
Measurements of the carrier to noise ratio (CNR) in Co-Cr/Ni-Fe double layer media for perpendicular magnetic recording were made to investigate the wavelength characteristics of CNR. CNR is constant at long wavelengths, and decreases proportionately as wavelength decreases at short wavelengths.