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Guided Scrambling: A New Coding Technique for Holographic Storage

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this paper, is to directly employtheintensitycharacteristics in the frequency domain. As coding method weweuseguided scrambling [3]. Guided scrambling (GS) is a member of a larger class of related coding schemes called multi-mode code. In multi-mode codes, each source word can be represented by a member of a selection set consisting of L codewords. The encoder evaluates the "quality" of each codeword in the selection set, and transmits that codeword that "best" matches the quality criterion at hand. The members of the selection sets are not judiciously chosen and stored in memory, but are randomly picked. The basic idea is that, provided the selection set is sufficiently large, we will find, with high probability, an adequate codeword fulfilling the constraints. The advantage of this approach is clear: at the encoder site we only need a) a simple mechanism for translating source words into "random" codewords and b) a mechanism for evaluating the "quality" of the candidate words. The stumble blockofconventional large codes, the look-up table, can be avoided, and replaced by a simple randomization algorithm. The paper is organized as follows. Section 2 analyses the distribution of extreme value of power intensity. The GS coding scheme is then described in Section 3. The computer simulation results of the GS coding are provided in Section 4. Finally,inSection5we conclude the paper 2 Extrema of the Power Intensity Distribution In digital holographic data storage, the data is commonly recorded as Fourier holograms, which are the two-dimensional frequency-domain data arrays (pages). Assume the source data are random symbols drawn from the alphabet f;1# 1g, then (see Appendix) the power intensity I at an arbitrary, non-zero, frequency pointfollows, by good approximation, an...
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Conference Paper
The holographic digital data storage (HDDS) system has been investigated for next generation digital storage due to its high storage density and high data transfer rates (J.F. Heanue et al., Science, pp. 749-752, 1994). Various modulation codes have been introduced to mitigate noise problems in HDDS systems (H.J. Coufal et al., Holographic Data Storage, Springer 2000). In this paper, a new 2D modulation scheme, or CCBM (code-word complementing block modulation), is proposed. The CCBM yields a pseudo-random array consisting of codewords with multiple weights (K. Kim et al., Proc. Satellite ISOM 2000, pp. 46-47, 2000; E. Hwang et al., Tech. Dig. ISOM 2001, pp. 142-143, 2001), and consequently gives spectral smoothing and constant energy in the modulated pages of data. This paper also covers a novel detection scheme in conjunction with the proposed CCBM. The results of numerical simulations and actual recording experiments are presented to verify the performances of CCBM. In a noisy HDDS channel, the results show that CCBM outperforms the guided scrambling (GS) method in terms of SNR and BER (bit error rate).
Book
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Preface to the Second Edition About five years after the publication of the first edition, it was felt that an update of this text would be inescapable as so many relevant publications, including patents and survey papers, have been published. The author's principal aim in writing the second edition is to add the newly published coding methods, and discuss them in the context of the prior art. As a result about 150 new references, including many patents and patent applications, most of them younger than five years old, have been added to the former list of references. Fortunately, the US Patent Office now follows the European Patent Office in publishing a patent application after eighteen months of its first application, and this policy clearly adds to the rapid access to this important part of the technical literature. I am grateful to many readers who have helped me to correct (clerical) errors in the first edition and also to those who brought new and exciting material to my attention. I have tried to correct every error that I found or was brought to my attention by attentive readers, and seriously tried to avoid introducing new errors in the Second Edition. China is becoming a major player in the art of constructing, designing, and basic research of electronic storage systems. A Chinese translation of the first edition has been published early 2004. The author is indebted to prof. Xu, Tsinghua University, Beijing, for taking the initiative for this Chinese version, and also to Mr. Zhijun Lei, Tsinghua University, for undertaking the arduous task of translating this book from English to Chinese. Clearly, this translation makes it possible that a billion more people will now have access to it. Kees A. Schouhamer Immink Rotterdam, November 2004
Article
Full-text available
A multiple page fully digital holographic data storage system is demonstrated. This system is used to store and retrieve digital image and compressed video data with a photorefractive crystal. Architecture issues related to spatio-rotational multiplexing and novel error-correcting encoding techniques used to achieve low bit-error rates are discussed.
Article
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In holographic storage, two-dimensional arrays of binary data is optically recorded in a medium via an interference process. To ensure optimum operation of a holographic recording system, it is desirable that the patterns of 1s (light) and 0s (no light) in the recorded array satisfy the following modulation constraint: in each row and column of the array there are at least t transitions of the type 1→0 or 0→1, for a prescribed integer t. A two-dimensional array with this property is said to be a conservative array of strength t. In general, an n-dimensional conservative array of strength t is a binary array having at least t transitions in each column, extending in any of the n dimensions of the array. We present an algorithm for encoding unconstrained binary data into an n-dimensional conservative array of strength t. The algorithm employs differential coding and error-correcting codes. Using n binary codes-one per dimension-with minimum Hamming distance d⩾2t-3, we apply a certain transformation to an arbitrary information array which ensures that the number of transitions in each dimension is determined by the minimum distance of the corresponding code
  • A Vardy
  • M Blaum
  • P H Siegel
  • G T Sincerbox
A. Vardy, M. Blaum, P.H. Siegel, and G.T. Sincerbox, \Conservative Arrays: Multi-Dimensional Modulation Codes for Holographic Recording", IEEE Trans. Inform. Theory, vol. IT-42, no. 1, pp. 227-230, Jan. 1996.