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Properties and constructions of binary channel codes

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Channel codes, sometimes called transmission or line codes, are applied in storage systems such as magnetic tape or disc and optical discs. Applications are also found in transmission systems over fiber or metallic cable. A channel code converts the digital source information to a form suitable for a specific transmission medium. For example DC-free codes are designed in such a way that the encoded signal has suppressed frequency components in the region around zero frequency. These codes are for example applied in transmission systems having insufficient response in the low-frequency range. Another requirement imposed on a channel code originates from the fact that the maximum distance between transitions in the encoded signal, the maximum 'run length', should be limited to enable a simple system clock recovery in the receiver. This thesis deals with systematic methods of designing DC-free and run-length-limited codes. Procedures are given for a simple enumerative encoding and decoding of the codewords. Also described are several properties of channel codes such as spectral and run length distributions. Criteria derived from information theory are used to compare the channel codes.
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... Enumerative encoding and decoding methods for DC-free sequences were suggested by Norris and Bloomberg [9], Immink [10], Vasilev [11], Braun and Immink [3]. A method for enumerative encoding these sequences with predefined dc component of the DFT z * 0 = n j=1 z j , which is usually called a digital sum or a charge of the sequence z, was suggested in [12]. ...
... This allows extension of the spectral null control from zero up to the Nyquist frequency. Enumerative encoding and decoding methods for DC-free sequences were suggested by Norris and Bloomberg [9], Immink [10], Vasilev [11], Braun and Immink [3]. A method for enumerative encoding these sequences with predefined dc component of the DFT z * 0 = n j=1 z j , which is usually called a digital sum or a charge of the sequence z, was suggested in [12]. ...
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