Effect of transition noise on the signal-to-noise ratio of magnetooptic read channels

Abstract

The effect of transition noise on the soft bit error rate (BER) and the signal-to-noise ratio (SKR) in magnetooptic (MO) recording systems is studied. With high-density MO recording transition noise and intersymbol interference (ISI) become problems. To study the effect of transition noise on the BER we model the MO channel in the presence of transition noise. We develop separate models for the peak-position modulation (PPM) and pulse-width modulation (PWM) in order to understand the differences in the performances of the two different writing formats. We also describe how run-length-limited (RLL) coding can be incorporated into the models. Using the models developed we study the effect of transition noise on the BER and the SNR for the decision feedback equalizer (UFE) method and the adaptive threshold deledion scheme. Our study indicates that the DEE yields better SNR than the adaptive threshold detector. Also the BER of PWM is better than the BER of PPM for the same user density. This implies that higher user densities can be achieved with PWM than with PPM for the same quality disk. © 1996 IEEE.