Timing sensitivity of decision feedback and partial response detectors in magnetic recording

In this paper, we investigate the effect of timing offset on the performance of MDFE (multi-level decision feedback equalization) and PR-VD (partial response with Viterbi detection) detectors, in magnetic recording applications. We develop analytical approaches to evaluate the performance using error event rate as a measure. The main step in this evaluation is the computation of the probability density function of residual ISI (inter-symbol interference) arising from mis-equalization and timing offset. The resulting performance curves are compared with those obtained from simulations. The detection performance due to steady-state phase jitter is also evaluated. The results show that MDFE is better than PR-VD in terms of timing sensitivity.