Bit-patterned media recording (BPMR) is one of the most promising candidates to further increase recording density beyond 1 Tb/in2. For high-density BPMR systems, severe intertrack interference (ITI) and media noise caused by decreased track pitch bring severe deterioration to the readback signals. To mitigate the impact of ITI and media noise on bit error rate (BER) performance, we developed a multitrack detection scheme with a two-dimensional (2-D) hybrid equalizer, which utilizes 2-D distinct equalizer coefficients corresponding to the different estimated ITI patterns. By analyzing the probability density distribution of the log likelihood ratio (LLR) output by the decoder, a LLR threshold is implemented to evaluate the reliability of estimated ITI patterns. Then, the 2-D variable equalizer trained with different ITI patterns is implemented for the reliably estimated ITI patterns; otherwise a 2-D fixed equalizer trained with a pseudorandom bit sequence is utilized. Hence, compared to the conventional 2-D fixed equalizer, the 2-D hybrid equalizer decreases the mean squared error of equalization with reduced error propagation risk. The simulation results indicate that the 2-D hybrid equalizer provides increased signal-to-noise ratio gains compared to the 2-D fixed equalizer when the media noise and track misregistration become more severe.

中文翻译：

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使用 2D 混合均衡器进行多轨检测，用于高密度位模式媒体录制

位模式媒体记录 (BPMR) 是将记录密度进一步提高到 1 Tb/in2 以上的最有希望的候选者之一。对于高密度BPMR系统，轨道间距减小引起的严重的轨道间干扰（ITI）和介质噪声会给回读信号带来严重的恶化。为了减轻 ITI 和媒体噪声对误码率 (BER) 性能的影响，我们开发了一种带有二维 (2-D) 混合均衡器的多轨检测方案，该方案利用对应于不同估计值的二维不同均衡器系数ITI 模式。通过分析解码器输出的对数似然比（LLR）的概率密度分布，实现了一个LLR阈值来评估估计的ITI模式的可靠性。然后，对可靠估计的ITI模式实施了用不同ITI模式训练的二维可变均衡器；否则使用用伪随机位序列训练的二维固定均衡器。因此，与传统的二维固定均衡器相比，二维混合均衡器降低了均衡的均方误差，同时降低了误差传播风险。仿真结果表明，当媒体噪声和轨道失配变得更加严重时，与二维固定均衡器相比，二维混合均衡器提供了更高的信噪比增益。二维混合均衡器降低了均衡的均方误差，同时降低了误差传播风险。仿真结果表明，当媒体噪声和轨道失配变得更加严重时，与二维固定均衡器相比，二维混合均衡器提供了更高的信噪比增益。二维混合均衡器降低了均衡的均方误差，同时降低了误差传播风险。仿真结果表明，当媒体噪声和轨道失配变得更加严重时，与二维固定均衡器相比，二维混合均衡器提供了更高的信噪比增益。