| 摘要 |
A dc-free coding scheme that also provides channel gain employs a code that is based on an alphabet of two and comprises a list of N-dimensional vectors, where N is even, with a maximum run of two symbols. From this list, all vectors which begin or end in two identical symbols are eliminated. This avoids runs of longer than two consecutive symbols when vectors are concatenated. With this scheme, if the baseband transmission of a "+" is realized with positive voltage V and transmission of a "-" is realized with a negative voltage -V, then any concatenation of symbols is dc-free. Improved coding gain is realized by mapping modulated signals onto convolutional code trellises.
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