Read Channel Designs for Efficient Data Recovery in Storage Systems Employing Imperfect Patterned Media

The general view is that the current use of a continuous magnetic thin-film for data storage will not be suitable for attaining storage densities in excess of 1Tbit/in². As such, new storage technologies, such as the use of a patterned medium, must be explored. However, the development of patterned media as viable storage media is limited by the availability of cost-effective fabrication techniques. In addition, the variation in island size and distribution due to the limitations of current fabrication techniques introduces lithography jitter in the replay signal, which invariably affects the ability to recover recorded data. The data recovery process from a magnetic storage system incorporating patterned media was initially analysed by Hughes [1999] and more recently by Nutter et al. [2004], where the effect of the media configuration on the bit-error-rate (BER) performance of the read channel was explored and the BER was shown to highly dependent upon the amount of lithography jitter present. These results will undoubtedly have a considerable effect on the commercial viability of data storage on patterned magnetic media and will define suitable manufacturing processes for the fabrication of such media. The aim of this paper is to investigate how careful media design and the use of low density parity check (LDPC) codes, can be used to optimise the read channel BER performance in the presence of lithography jitter, as well as offer increased areal density without sacrificing too much BER performance.