| 摘要 |
<p>In a time-division digital transmission system comprising transmitting and receiving stations interconnected by transmission lines, a number of component digital channels having a low flow rate are multiplexed into a single resultant channel having a high flow rate. The code used in the stations is a binary code and the code used in the lines is a multi-level code such that a number N of bits in the binary code corresponds to a smaller number N' of digits of the multi-level code. Consequently, a predetermined flow rate in the stations corresponds to a smaller flow rate in the lines, equal to N'/N times the flow rate in the stations. The system comprises, in the transmitting part of a station, means for placing in parallel the bits of a number of component channels equal to a multiple k of N, at the rate of one bit per component channel, so as to form parallel words of kN bits, means for multiplexing the bits of the parallel kN-bit words into k parallel words of Nbits, and means for converting the parallel N-bit words from said binary code into parallel words of N' digits in said multi-level code. In the receiving part of a station, the system comprises means for distributing the bits of the parallel words of kN bits at the rate of one bit on each of the kN component channels, means for converting the parallel N'-digit words into parallel N-bit words of said binary code, means for forming parallel words of kN bits out of a number k of N-bit words supplied by the latter said converting means and means for demultiplexing the parallel kN-bit words into kN bits at the rate of one bit per component channel.</p> |
