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AssigneeKoninklijke Phillips Electronics N.V.
InventorWillem Marie Julia Marcel Coene
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The invention relates to a method of converting a stream of databits of a binary information signal into a stream of databits of a constrained binary channel signal, this signal being constructed by repetitively or alternate using a channel code C1 and a channel code C2. Due to the fact that two channel words with opposite parities are available in the channel code C2 for each information word, and that the same state is established, predetermined properties of the constrained binary channel signal can be influenced, e.g. for performing guaranteed DC-control, i.e. independent of the contents of the stream of databits of the binary information signal. Due to the fact that the method further comprises the step of substituting, in dependence upon a value of a predetermined property of the binary channel signal, a channel word for a substitute channel word, wherein the substituted channel word and the substitute channel word establish the same state, predetermined properties of the constrained binary channel signal can be further influenced. The invention further relates to a device for encoding, a signal, a record carrier, a method for decoding and a device for decoding.
A method of converting a stream of databits of a binary information signal into a stream of databits of a constrained binary channel signal, wherein the stream of databits of the binary information signal is divided into n-bit information words (1), said information words being converted into m1-bit channel words (2) in accordance with a channel code C1, or m2-bit channel words (3) in accordance with a channel code C2, where m1, m2 and n are integers for which it holds that m2>m1>n, wherein the m2-bit channel word is chosen from at least two m2-bit channel words at least two of which have opposite parities, the concatenated m1-bit channel words and the m2-bit channel words complying with a runlength constraint of the binary channel signal, the method comprising the repetitive and/or alternate steps of:
A device for encoding (100) a stream of databits of a binary information signal (101) into a stream of databits of a constrained binary channel signal (103), for performing one of the methods as claimed in any one of the preceding claims, the device comprising an n-to-m1-bit converter (102) for converting the n-bit information words into m1-bit channel words, an n-to-m2-bit converter (102) for converting the n-bit information words into m2-bit channel words, state-establishing means (104) for establishing a coding state of the m1-bit channel words and of the m2-bit channel words, said n-to-m1 bit converter being further arranged to select the m1-bit channel word depending on the end part of the preceding channel word, said n-to-m2 bit converter being further arranged to select the m2-bit channel word depending on the end part of the preceding channel word, wherein the n-to-m1-bit converter and/or the n-to-m2-bit converter comprise substitution means for substituting a limited number of channel words for substitute channel words so as to influence predetermined properties of the binary channel signal, the substituted channel word and the substitute channel word establishing the same state.
A device for decoding (132) a stream of databits of a constrained binary channel signal (131) into a stream of databits of a binary information signal (134), the device comprising converting means for converting the signal into a bit string of bits having a first or a second value, the signal comprising the m1-bit channel words and the m2-bit channel words, the bit string comprising the n-bit information words, wherein one n-bit information word is assigned to one channel word or to one substitute channel word.
Dependencies are inferred from the claim text.