Detection performance in the presence of transition noise

The performance of various detector/RLL (run-length-limited) code combinations was investigated assuming the presence of both additive white noise and transition noise. The results indicate that for detectors relying heavily on linear suppression of ISI (intersymbol interference), the transition-noise effect does not show up at high densities because of relatively severe enhancement of the additive-noise component. However, transition noise degrades performance of FDTS/DF (fixed delay tree search with decision feedback) and DFE (design feedback equalizer), as a large amount of ISI is allowed at the equalizer output to avoid the excessive additive-noise enhancement. Nevertheless, the FDTS/DF still has substantial performance gain over other detectors. Effects of position jitter and width variations have also been observed separately. It was found that the simple peak detector performs comparatively well in the presence of position jitter, whereas sequence detection schemes that permit a relatively large amount of ISI at the linear equalizer output are more sensitive to position jitter than to width variations, except at low uncoded-densities. It was also observed that the signal-to-noise ratio penalty incurred by the d-constraint is significantly reduced in the transition-noise environment compared to the additive-noise environment