Title :
The role of SP in data-storage systems
Author_Institution :
Dept. of Electr. Eng., Minnesota Univ., Minneapolis, MN, USA
fDate :
7/1/1998 12:00:00 AM
Abstract :
Among the key components in the development of a successful storage system are heads, media, and signal processing. In the past, major breakthroughs in the heads and media technologies have been mainly responsible for the spectacular growth in storage capacity, but signal processing is increasingly recognized as a cost-efficient means of improving density. This article addresses the issues relevant to signal processing. While the focus is on magnetic storage, most of the signal-processing strategies discussed are also applicable to optical storage. This article begins with a description of the read/write (R/W) process in magnetic storage. The characteristics of noise and nonlinearity present in real magnetic storage channels are also discussed, and a discussion on channel modeling is followed by a description of different modulation codes. Different suboptimal sequence detectors and equalizers are then presented that represent the techniques that are either already in use in commercial systems or being investigated for near-future applications. We then discuss sequence detectors, with in-depth treatment given to those based on tree search, particularly finite or fixed delay tree search (FDTS) detectors. Finally, performance evaluation results are presented under various channel conditions, which should be useful in assessing the potential benefits of different coding and sequence-detection strategies
Keywords :
decision feedback equalisers; delays; encoding; magnetic disc storage; modulation coding; optical storage; pulse amplitude modulation; signal detection; signal processing; telecommunication channels; tree searching; PAM communication channel; channel conditions; channel modeling; data-storage systems; decision feedback equaliser; equalizers; finite delay tree search detectors; fixed delay tree search detectors; magnetic disk drive systems; magnetic heads; magnetic storage channels; media technologies; modulation codes; noise characteristics; nonlinearity; optical storage; performance evaluation results; read/write process; signal processing; storage capacity; storage density; suboptimal sequence detectors; Detectors; Magnetic heads; Magnetic memory; Magnetic modulators; Magnetic noise; Modulation coding; Optical modulation; Optical noise; Optical signal processing; Signal processing;
Journal_Title :
Signal Processing Magazine, IEEE