| 摘要 |
For a digital communications system with binary signal transmission, preferably an optical transmission system, a line coding suitable for the required direct-current characteristics and error correction capacity is to be specified. The code converter according to the invention consists of a coder (10) which converts the binary signals to be transmitted in parallel into an error-correcting code, preferably a convolutional code, and a subsequent adder which adds an auxiliary word, adapted to the coder, to the parallel output signals of the coder (10). Correspondingly, the code converter at the receiving end consists of an auxiliary-word subtracter (16) which subtracts the auxiliary word again from the received signals, and of a subsequent decoder (17) which converts the error-correcting code into the original code again. The auxiliary word is selected in such a manner that it generates an adequate number of symbol changes in the transmitted signal and that the transmitted signal has good self-synchronisation characteristics. Additional devices (60, 61, Fig 4; 70, 71, 72, Fig. 5) are provided in order to transmit service channel data with a bit repetition rate which is much lower compared with the other digital signals, with the aid of code redundancy. For the purpose of signal processing in the convolutional coders/decoders at a very high processing speed, suitable circuits (Fig. 8, Fig. 9) for logic operations ... Original abstract incomplete. <IMAGE>
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