DFE timing acquisition: analysis and a new approach for fast acquisition

The problem of timing acquisition in decision feedback equalization (DFE) detectors for magnetic recording channels, in particular the multi-level DFE (MDFE), is considered. We first address the issue of the optimal choice of preamble pattern for timing acquisition and show that a 6T periodic pattern (T being the bit period) is optimum for medium to high user densities. Next, we show that the MDFE timing-error detector using the 6T-pattern is near optimum for acquisition. Finally, we propose a novel threshold-based fast acquisition scheme that can eliminate false lock and effectively prevent hang up problems.