Signal Processing and coding for High Density Magnetic Recording Channels

William E. Ryan RIA：高密度磁记录通道的信号处理和编码在这个项目中，我们首先仔细研究了先前报道的高密度磁记录通道（MRCs）错误控制代码性能的结果。特别是，我们推导出最优码率（在最大化编码增益的意义上），然后在假设无限和有限解码努力的情况下检查最优码率码所提供的增益。以前的工作研究了假设无限解码努力的非最优速率码的编码增益。我们将比较编码MRC的最大似然序列检测（MLSD）的性能与等效复杂性的部分响应形状的未编码MRC的性能。这种部分响应形状将由本研究确定。这项工作在非常高密度的记录系统中有应用，其中代码实际上可能导致性能损失。我们将寻求找到适合于常用约束码的部分响应形状，当与MLSD结合使用时，可以提供对当今逐位检测器的改进。这项研究将包括计算机模拟和分析，并将检查编码和部分响应技术在实际记录器上的有效性。特别是，我们将研究对非线性干扰，覆盖和增加磁道密度的抗扰性。

William E. Ryan RIA: Signal Processing and Coding for High Density Magnetic Recording Channels In this project we first take a closer look at previously reported results on the performance of error control codes on high density magnetic recording channels (MRCs). In particular, we derive optimal code rates (in the sense of maximizing coding gain) and then examine the gains afforded by optimal rate codes assuming both infinite and finite decoding effort. Previous work examined coding gains of non-optimal rate codes assuming an infinite decoding effort. We will compare the performance of maximum likelihood sequence detection (MLSD) of a coded MRC with that of an uncoded MRC equalized to partial response shape of equivalent complexity. Such partial response shapes are to be determined by this research. This work has applications in very high density recording systems where codes may in fact be responsible for a performance loss. We will seek to find partial response shapes appropriate for commonly used constrained codes which, when combined with MLSD, provide an improvement over today's bit-by-bit detectors. The study will include both computer simulations and analysis and will examine the effectiveness of coding and partial response techniques on actual recorders. In particular, we will examine the immunity to nonlinear interference, overwrite, and increased track density.