MAP-Based Timing Recovery for Magnetic Recording

We consider the problem of timing recovery in magnetic recording channels based on MAP estimation of the timing information. The read and write clocks are modeled as random walk processes that allow for slowly varying phase and frequency offsets of the clocks. We propose a new timing error detector (TED) that provides sufficient statistics about the instantaneous timing error. Using the clock models and the new TED, the MAP estimates of the sampling times are derived. This method is shown to be more robust than the conventional algorithm based on the Mueller and Muller TED and easily implementable for a small additional complexity.