BIT ERRORS DUE TO CHANNEL MODULATION OF MEDIA JITTER

Recording media written-in transition jitter noise can limit magnetic recording systems. Read channel intersymbol interference (ISI) modulat es media jitter in a head/disk/channel, attenuating jitter at low line ar density due to classical ISI but amplifying at high density [5]. Th is paper assesses whether jitter modulation is significant in typical disk drive peak detect (PD) and partial response (PR) channel design, where maximum linear bit density is sought at a specified bit error ra te (BER). Experimental isolated pulse data, transition noise, and elec tronic noise measurements from a 65 mm head/disk recording design are used as inputs to a Matlab simulation of PD and PR Lorentzian channel low pass and boost filters, PD differentiator filter, PR digital filte r, and PD/PR bit detectors. The goal of such models is optimizing the designable PD and PR channel parameters for realistic maximum linear d ensity prediction. However their complexity obscures the jitter modula tion contribution, which is demonstrated here by the shift in the BER versus density curves, when the jitter modulation is mathematically tu rned off. Jitter modulation is thereby shown to be significant but not dominant in (1,7) PD density limits. About an order of magnitude BER loss due to jitter modulation can occur at typical PD linear channel b it densities P-50/T approximate to 2 Jitter amplification in PD channe ls can occur at channel density 3.8 (above usable PD limits). PR chann els only amplify media jitter, degrading BER by about an order of magn itude at typical (0, k) PR4 densities, and degrading timing channel ac curacy twice as fast as channel density increases. Lorentzian isolated pulse (ISOP) modeling is compared to recording physics mathematical p ulses, and simulation statistical validity checks are made.