Minimum-Bit-Error Rate Tuning for 2D-Pdnp Multitrack Detection

Abstract

A dominant impediment in magnetic recording is pattern-dependent media noise, and its impact will only grow more severe as areal densities increase. The pattern-dependent noise prediction (PDNP) algorithm [1] [2], widely used as an effective strategy for mitigating pattern-dependent media noise in single-track detection, has recently been extended to the multitrack scenario [3]; it uses 2D patterns (spanning multiple tracks) to mitigate both downtrack and crosstrack pattern-dependent noise, based on the architecture shown in Fig. 1. The sampled readback waveforms are filtered by a $2 \times 2$ MIMO equalizer with coefficients $\mathbf{C}$, whose output $\mathbf{y}_{k}=\left[y_{k}^{(1)}, y_{k}^{(2)}\right]^{T}$ is passed to a 2D -PDNP multitrack detector. Associated with each 2D bit pattern is a signal level vector $\mathbf{s}$, a standard deviation diagonal matrix $\Lambda$, and a set of matrix-valued predictor coefficients $\mathbf{P}_{0}, \mathbf{P}_{1}, \ldots, \mathbf{P}_{N_{p}-1} $. The branch metric of edge e for the 2D -PDNP Viterbi detector is [3]: