This study presents a 9/12 two-dimensional (2D) modulationcode as a way to overcome 2D intersymbol interference (ISI) in high-density storage systems. The next generation of data-storage systems is being continually ...
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This study presents a 9/12 two-dimensional (2D) modulationcode as a way to overcome 2D intersymbol interference (ISI) in high-density storage systems. The next generation of data-storage systems is being continually developed to satisfy a massive demand for reliable storage regarding enormous amounts of data. Holographic data storage, bit-patterned media recording (BPMR), and 2D magnetic recording are promising candidates for the attainment of area-density increases that are beyond the capacities of conventional storage systems. One of the main challenges for these systems is a 2D ISI problem consisting of 1D ISI from neighbour bits and intertrack interference from adjacent tracks. The proposed modulationcode maps every 9 bit sequence of user data into a 2D output array of a 3-by-4 size so that the fatal 2D ISI patterns are avoided in every output array. For the assessment of the quality of the proposed modulationcode, a simulation model is carried out in a BPMR system. The results show that the proposed modulationcode offers a gain of approximate to 2 dB over that of a system without encoding. In particular, a gain of approximate to 1 dB is obtained over that of a 6/8 modulationcode regarding the same code rate.
The performance of a rate-4/5 modulationcode is evaluated in two-dimensional magnetic recording (TDMR) channels, where a magnetic medium is described by a discrete Voronoi model, and the two-dimensional sensitivity f...
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The performance of a rate-4/5 modulationcode is evaluated in two-dimensional magnetic recording (TDMR) channels, where a magnetic medium is described by a discrete Voronoi model, and the two-dimensional sensitivity function of the reader is adopted to generate the TDMR readback signal. Since the read-head sensitivity function covers many tracks, it causes intertrack interference (ITI) that can deteriorate the system performance. Therefore, this letter proposes an ITI subtraction scheme in conjunction with the rate-4/5 modulationcode in a coded TDMR channel to mitigate the ITI effect embedded in the readback signals before performing an iterative decoding process. We also investigate the data-dependent readback amplitude distributions and evaluate the TDMR system performance via computer simulation. Results show that the proposed scheme helps improve the TDMR system performance, especially when the areal density is high.
The decoding performance of the 4/9 code, which depends on the accuracies of similarity comparisons for the code and the positional marker, was computationally evaluated in response to translation disturbances. The re...
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The decoding performance of the 4/9 code, which depends on the accuracies of similarity comparisons for the code and the positional marker, was computationally evaluated in response to translation disturbances. The reproduction bright spot size (phi) was constrained to be smaller than the image-sensor pixel pitch (p) for the code, and phi > p was necessary for the marker. These contradictory requirements were solved by a reproduction method in which a large numerical aperture (NA) was set for the code and a small NA was set for the marker. A bit error rate of 10(-4) and a position detection resolution of similar to p/10 were confirmed in the read-only-type holographic memory where the above method using two different NAs was applied. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3481103]
A channel data retrieval scheme for page-based holographic data storage has been developed. It includes several signal-processing blocks for retrieving data reliably under noisy condition, namely, a frame grabber for ...
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A channel data retrieval scheme for page-based holographic data storage has been developed. It includes several signal-processing blocks for retrieving data reliably under noisy condition, namely, a frame grabber for capturing data adaptively in a rotating disk, a mark detector for tracing the data location, an equalizer for compensating interference, a two-dimensionalmodulation decoder for suppressing errors, and a three-dimensional error correction decoder for correcting errors generated by the holographic storage channel. The proposed scheme has been implemented with a field-programmable gate array chip and applied to actual data retrieval from holographic data storage. With the proposed channel data retrieval hardware, the user video data is successfully reconstructed from the holographic disk, which contains video data as holograms.
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