| 摘要 |
15. A message transmission installation comprising at least two stations each capable of acting as a transmitter and receiver, each station comprising apparatus capable of acting as a transmitter and receiver of information, a mixer, and a circuit for generating reproducible series of code pulses having a long period, said circuit comprising a binary counting chain having at least 20 members, connections connecting each of said members to a respective mixer, a plurality of shift register elements constituting a shift register chain, connections connecting each mixer to a respective shift register element, to a previous shift register element in the chain and to a switching distributor the state of which is determined by a switching criterion, the arrangement being such that the mixers mix the information content of one counting member of the counting chain with the information of one shift register element and this mixed information is delivered to the next shift register element if the state of the switching distributor is in accordance with the switching state of the corresponding member of the counting chain, and that the information of one shift register element is delivered to the next shift register element unchanged if the state of the switching distributor differs from the switching state of the corresponding member of the counting chain.
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